Free Flip-Book Zoology Class 11th & 12th by Study Innovations

Excretory Products and their Elimination

• Abnormal constituent of urine – (i.e. Not present in normal condition)
1. Protein – If protein is present in urine it may be due to infection or injury in kidney. (Mainly albumin is filtered)
2. Blood – Due to infection and injury of kidney blood may appear in urine.
3. Sugar – In diabetes mellitus sugar appear in urine.
4. Bile of bile pigment – In jaundice bile pigment appear in urine.
5. Ketone bodies – In starvation and diabetes. Ketone bodies appear in urine.

• Diabetes mellitus – Sugar appear in urine due to hyposecretion of insulin.
• Diabetes incipidus – Tasteless more urine passing due to hyposecretion of A.D.H.

c

Chapter 12 298

ZOOLOGY
CHAPTERS 13-15

BOOKLET-3

Contents:
Chapter 13 Locomotion and Movement
Chapter 14 Neural Control and Coordination
Chapter 15 Chemical Coordination and Integration

Locomotion and Movement

Introduction : That branch of science which deals with bones and cartilage is called Osteology. Bones are
made up of a protein called ostein and cartilage are made of a protein called chondrin. Hence study of bones is
called osteology and study of cartilage is called chondrology. Body of animals (vertebrates) is supported by skeleton.

Skeleton
The hardened tissues of the body together form the skeleton (sclero = hard). Organism will remain small and

slow moving if there had been no skeleton for support and to serve as levers on which muscles can act. Skeleton of
invertebrates is most often secreted on the surface, forming a lifeless or dead exoskeleton. Whereas skeleton of
vertebrates develops most often underneath the surface forming a living or growing endoskeleton. Three types of
skeletons develop in vertebrates :

(i) Epidermal horny exoskeleton : These include hard and horny of keratinized derivatives of epidermal
layer of skin, such as claws, reptilian scales, bird feathers and mammalian hairs, horns, nails and hoofs, etc. All
living amphibians lack an exoskeleton.

(ii) Dermal bony skeleton : Dermal bony skeleton is derived from the dermis of skin. It includes bony scales
and plates or scutes (osteoderms), finrays and antlers of fishes, reptiles and mammals. In fishes, dermal scales
become exposed due to wearing out of epidermis, and form exoskeleton.

(iii) Endoskeleton : Greater part of vertebrate skeleton lies more deeply, forming the endoskeleton. It
develops from mesenchyme. Endoskeleton is formed by bones in vertebrates. Skeleton in different animals are as follows –

Invertebrate –

• Protozoa – No skeleton.

• Porifera – Calcarius spicules + silicious spicules + spongin fibre.

• Spicules in porifera represent endoskeleton.

• Coelentrata – Calcareous corals.

• Helminth – No skeleton, cuticle present.

c• Annaelida – No skeleton, cuticle present.
In earthworm and ascaris is hydrostatic skeleton is found that is fluid is filled in coelom and form turgid
skeleton.

• Arthropoda – Chitinus exoskeleton.

• Chitin is modified cuticle.

• Mollusca – Calcarius shell.

• Echinodermata – Calcareous plates are present.

• In vertebrates exoskeleton may be epidermal or dermal.

Vertebrates : In vertebrates dermal skeleton is formed by bones. Bone is the connective tissue with

intercellular spaces filled with ossein matrix composed of calcium salts 2/3 (Ca Po4 , Ca2 (SO4 )3 ), CaF2CaCO3 and

calcium oxalate) and organic matter 1/3. In the ossein osteocyte cells are found and outer surface of bone is
covered by periosteum. The inner most region is full of bone marrow having various types of cells. In mammals the
bone is full of haversian canals. The bones are of three types :

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(a) Cartilage bones : The bones which are formed by the ossification of preexisting cartilage are called
cartilage bones or replacing bones.

(b) Membrane or dermal bones : The bones which are formed by independent ossification in connective
tissue are called dermal, membrane or investing bones.

(c) Sesmoid bone : Ossification takes place on Ligament and Tendons.

(1) Functions of endoskeleton : Chief function of vertebrate endoskeleton can be enumerated as follows –

(a) To provide physical support to body by forming a firm and rigid internal framework.

(b) To give definite body shape and form.

(c) To protect by surrounding delicate internal organs like brain, heart, lungs etc.
(d) To permit growth of huge body size (whale, elephant, extinct dinosaurs), since it is living and growing.
(e) To provide surface for attachment of muscles.
(f) To serve as levers on which muscles can act.
(g) To manufacture blood corpuscles in bone marrow.
(h) To help in breathing (tracheal rings, ribs).
Endoskeleton in vertebrate made up of :
(a) Axial endoskeleton : (Skull + Vertebral column + Sternum + Ribs)
(b) Appendicular endoskeleton : (Girdle + Limb bones)
SKULL
AXIAL SKELETON (ANTERIOR HEAD APPENDICULAR SKELETON
MID DORSAL) PECTORAL
GIRDLE
VERTEBRAL FORE LIMB
COLUMN
(ABDOMINAL GIRDLE
SIDE)(BACK SIDE)

cSTERNUMRIB (LATERAL)

PELVIS GIRDLE

LIMBS

HIND LIMB

(a) Axial skeleton : It occupies the body's main longitudinal axis. It includes four structure : skull in the head,
vertebral column in the neck, trunk and tail if present, sternum and ribs in the thorax. It form the upright axis of
body and includes 80 (87 in children) bones are as follows in man –

Cranium – 8 Hyoid – 1

Face – 14 28 Skull Vertebrae – 26 (33 in children)

Ear ossicle – 6 Sternum – 1

Ribs – 24

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(1) Skull (General structure) : It is anterior most

axial skeleton. It is divisible into two main parts –

(i) Chondrocranium (ii) Splanchocranium SPHENOID
ETHMOID
(i) Chondrocranium : Chondrocranium is formed by PARIETAL FRONTAL
(a) brain box or cranium proper and (b) two sense capsules –
FACE
Orbit or optic capsule (eye) and auditory or otic capsule (ear). LACRIMAL

(a) Cranium proper : It is a strong and firm bony box TEMPORAL NASAL

with a helmet-like covering over the brain, called vault of OCCIPITAL EYE ORBIT
MALAR
skull, and a relatively thicker and stronger floor of base upon (ZYGOMATIC)

MAXILLA CORONOID
MANDIBLE PROCESS
which the brain rests. Its cavity is called cranial cavity. Size ofcperforation for exit of I cranial nerve.EXTERNAL
cranial cavity averages 1475 cubic centimetres (cm3) in adult AUDITORY STYLOID
men. At about the middle of the floor of cranium, there is a PROCESS
large opening of cranial cavity called foramen magnum. The MEATUS
brain is connected to spinal cord at this foramen. Cranium
BASE OF SKULL CONDYLE

Fig. – Human skull viewed from right side

proper of mammal has four distinct zone –

(1) Occipetal zone : Occipital zone has one supra-occipital bone on dorsal side, one basioccipital on ventral

side and two exoccipital on both lateral side of foramen magnum. Foramen magnum is present in ventral side of skull,

which fills on Ist atlas vertebra. Two occipital condyles forming dicondylic skull at the junction of supra and exo-occipital.

(2) Parietal zone : In the dorsal side of cranium parietal zone has three bone, that is two parietal, one inter

parietal and ventral side of cranium has 3 bone i.e. one basisphenoid with pituitary foramen and two alisphenoid bone.

(3) Frontal : Frontal part of cranium has two frontal bone in dorsal side, each frontal bone has one process

called supra orbital process of frontal. Two orbitosphenoid, one presphenoid bone in ventral side.

(4) Ethmoidal : Ethmoidal part has one circular plate called cribriformplate. That plate is having two

SUPRA ORBITAL ETHMOIDAL ZONE
PROCESS OF FRONTAL WITH ONLY ONE

FRONTAL (2) BONE i.e. –
PERIETAL (2) CRIBRIFORM PLATE

ORBITAL CAPSULE
(EYE)

INTER EXTERNAL TYMPANIC
PARIETAL (2) AUDITORY METUS BULLA

SUPRA TYMPANIC OD
OCCIPITAL (1) BULLA

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Cranium

Occipital region Parietal region Frontal region Ethmoidal region Temporal region
(of cartilage bones)

Exoccipitals Supra occipital Basioccipiatal Orbitosphenoids Frontals Presphenoid
(on side) (on roof) (on floor) (on sides & floor)
(Cartilage bone) (on roof or Parasphenoid

membrane bone) (on floor – Median)

(Cartilage bone)

cWhen inter orbital septum is present in any skull then suchBasisphenoidParietals(Inter-parietal)Alisphenoids
(On floor Median) (on floor & sides)
(on roof) (Cartilage bone)
(Cartilage bone) (Membrane bone)

(b) Sense capsule : Chondrocranium contains two sense capsule. Ethmoid Ectethmoids or

(1) Optic or orbital capsule (2) Otic or auditory capsule (on floor median) lateral ethmoids
(on sides)
(1) Optic capsule : One pair of optic or orbital capsule are present in frontal zone of chondrocranium. It is
made up of 7 pairs of bones which are –

I – Pre frontal II – Post frontal III – Anterior orbital IV – Posterior orbital
V – Infra orbital VI – Supra orbital VII – Lacrymal

In frog optic capsules are absent but in place of optic

capsule eye-orbit are present in same position. In between two
eye capsule, a separating bone is present in mammals only. This
separating bone is called inter-orbital septum. This septum is
absent in frog between two eye orbits.
SEPTUM IN FROG

skull is called tropibasic skull. In tropibasic skull both eye face the front and can be directed at the same object, this

type of vision is called binocular vision. When inter-orbital septum is absent in skull, then such skull is called basic

platy skull with monocular vision. Inter-orbital septum is formed by 5 bones which are 2 orbitosphenoid, 2-

alisphenoid and one basissphenoid.

(2) Auditory or Otic capsule : Auditory capsule located between occipital and parietal zone. It has two
parts – Tympanic bulla and External auditory metus. Auditory capsule in vertebrates is formed by 5 pairs of otic bones.

(I) Preotic (II) Epiotic (III) Opisthotic

(IV) Sphaenotic (V) Pterotic

Out of these 5 pairs only I pair i.e. preotic participate in formation of auditory capsule of frog i.e. amphibian.
In mammals e.g. rabbit I, II & III pair fuse to form a fusion bone called periotic, which forms the auditory capsule. In
reptiles and birds (aves) all 5 pairs bone combinedly constitute auditory capsule. Membranous labyrinth is enclosed
in the pro-otic and tymanic bulla. Auditory capsule has two distinct part – Outer spongy part called patrus part and
Inner bony part called mastoid part.

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Auditory capsule Sense capsules Olfactory capsule

Orbital capsule (membrane bones)

Epiotic Opisthotic Prootic Sphenotic Pterotic Nasals Vomers
(Superior) (Posterior) (Anterior) present present (above) (below)
& Posterior & inferior & inferior

Form periotic in birds and mammals Present in Teleosts Membrane bones
fishes only
In amphibians and reptiles, however, only prootic is present.

Post-orbital Pre-frontal Supra-orbital Pre-orbital Lacrymal Post-frontal
(Postero-dorsal (Infront and on (Above the orbit) (Antero-dorsal (In front) (Behind and on
outer side of frontal) side of orbit) outer side of frontal)
side of orbit)cforms parts of lateral walls and floors of eye orbits.

(c) Skull of man : In man however the skull remain erect at top of vertebral column because of perfectly
erect posture of body it is divisible into the large and hollow cranium and the facial region.
(1) Cranium (Brain case) : In skull of man all eight bones are articulated with each other to form the

cranium as follows –

Name No. Description

Frontal 1 Forms the forehead (anterior or front part of the top of cranium) and some upper parts (roofs) of eye orbits or

sockets and nasal cavities. A newborn infant displays a faint suture in midline of frontal, indication that adult

frontal is actually formed of two completely fused frontal.

Parietals 2 Articulated to and situated just behind frontal. Form the main parts of bulging top and sides of cranium.

Occipital 1 Articulated to and situated just behind parietals. Forms posterior (back) and lower (base) parts of cranium.

Foramen magnum is a large perforation in this bone. On each side of the foramen, the occipital bears a

prominent elevation called occipital condyle. The condyles articulate the skull with first vertebra (atlas). Thus,

human skull is dicondylic.

Temporals 2 Form lower parts of right and left sides of cranium, as well as, the floor of cranial cavity. These house structures of

internal and middle ears and form a part of external auditory meatuses. The middle ear of each side encloses the

three small ear ossicles – malleus, incus and stapes.

Sphenoid 1 A typically butterfly-shaped bone that forms the middle and anterior parts of base of cranium in front of occipital

in the middle and temporals on the sides. It articulates with all skull bones, keeping these firmly together. It also

Ethmoid 1 A small, irregular bone in front of sphenoid and behind nasal bones. It fashions the front (anterior) extremity and

closer of cranial cavity. It also contributes to the architecture of eye orbits and proximal parts of nasal chambers.

(2) The facial region : This is the front or anterior part of our skull comprised of 14 bones as follows –

HARD PLATE

MAXILLA

PARIETAL LACRIMAL FRONTAL INTERNAL ZYGOMATIC
MAXILLA ARCH
SPHENOID ETHMOID INTERNAL SPHENOID
NARIS
NASAL EYE ORBIT VOMER
MAXILLA TEMPORAL
MIDDLE MALAR STYLOID
CHONCHA (ZYGOMATIC) PROCESS
NASAL SEPTUM MASTOID
INFERIOR PROCESS
CHONCHA
OCCIPITAL
VOMER CONDYL

OCCIPITAL PARIETAL

Fig. – Human skull viewed from in front Fig. – Human skull viewed from below

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Name No. Description

Nasals 2 Small, oblong bones in middle of upper part of face, forming proximal part of the bridge of our nose. The
remaining, lower part of our nose is formed of cartilage.

Inferior 2 Two highly coiled, scroll-like processes of ethmoid bone, called conchae project into each nasal cavity from
nasal lateral wall of the proximal bony part of concerned nasal chamber. One ethmoidal concha is superior
(uppermost). The other one is called middle concha, because it is followed by a thin, separate scroll-like bone
conchae which is named inferior nasal concha or turbinate.
(Turbinales)

Vomer 1 A thin, elongated, platelike bone, forming a part of the septum which separates the two nasal cavities.

Lacrimals 2 Small and thin, finger-shaped bones, each located in front part of the medial (inner) side of corresponding eye

orbit. these form a part of the passages of corresponding tear ducts.
2 Cheek-bones; form the prominences of our cheeks and parts of the floor and side walls of eye orbits.

2 L-shaped bones that form the back (posterior) part of our hard palate (roof of mouth). Also contribute to the
framework of nasal cavities and floor of eye orbits.

2 Large, upper jaw bones that form the major part of our face and upper jaw. Comprise entire front (anterior)
part of our hard palate. Also contribute to the architecture of eye orbits and nose. Bear the teeth of upper jaw.

1 Largest bone of our face, and strongest of all bones of the body. Forms entire lower jaw and bears all lower jaw
teeth. Articulated with temporal bones of skull.
Zygomaticsc(3) III to VII pair – Branchial arches
(Malars)
Palatines

Maxillae

Mandible

(ii) Splanchnocranium : It is also known as facial. It includes
following two parts –

(a) Visceral skeleton (b) Olfactory or Nasal capsule

(a) Visceral skeleton : Visceral skeleton is formed by pairs
of visceral arches which are –

(1) I pair – Mandibular arch

(2) II pair – Hyoid arch

The mandibular arch

(remaining 5 pairs)

Palato-pterygo-quadrate bar forming Meckel's cartilage (forming lower jaw)

Suspensorium Upper jaw

Quadrate Squamosal
(Autostylic suspensorium (Craniostylic
suspensorium in
in amphibia, reptiles
and birds) mammals)

Premaxilla Maxilla Palatine Pterygoid Jugal

Angular Articular Dentary Splenial Supra Coronary
angular

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(1) Mandibular arch (one pair) : It is made of two arches one is upper forming upper jaw and second is

lower called lower jaw. In tadpole stage upper jaw i.e. upper part of mandibular arch is formed by the fusion of

three cartilage called palatine, pterygoid and quadrate. These all fused to form palato-pterygoquadrate.

Lower jaw or II part of mandibular arch is cartilagenous initially and is called Meckel's cartilage which soon

changes into bony structure.

(i) Upper jaw : The upper jaw is made of 14 bones i.e. 7 pairs of bones which are –

(i) Premaxilla (ii) Maxilla (iii) Jugal (iv) Squamosal

(v) Pterygoid (vi) Palatine (vii) Quadrate.

Out of these 7 pairs of bones only quadrate are not visible because they constitute II ear ossicle i.e. – incus. In

man the nasal cavity is separated from the buccal cavity by bone called palatine complex. Palate of birds is identical

in animal kingdom, which is used for birds classification.
Upper jaw in vertebrate is completely ossified with skull but lower
Process of upper jaw
cjaw is always free from chondrocranium and hangs downwardly. A bone
(1) Premaxilla

• Nasal process on dorsal side which are covered by Nasal.

• Palatine process of premaxilla.

(2) Maxilla

• Nasal process of maxilla.

• Palatine process of maxilla.

• Zygomatic process of maxilla.

(3) Squamosal : Only zygomatic process of squamosal.

(ii) Lower jaw : It is composed of 6 pairs of bone i.e. 12 bones maximum. These are articular, angular,

splenial, dentary, coronoid and supra angular.

In frog out of 6 pairs only 4 pairs of bones are present. Only 3 pairs form lower jaw and one pair forms I ear
ossicle i.e. collumella aures. Remaining 3 pairs i.e. Angular, splenial and dentry combine to form lower jaw of frog.

In mammals only one pairs of bones are present of which only one pair i.e. dentry from lower jaw. In the process
development cartilaginous dentry become offified due to osteocytes. Articular of lower jaw forms malleus i.e. I ear
ossicle. All the 6 pairs of bones are present in lower jaw of reptilies and aves.

GREATER
CORNU

hangs lower jaw from upper jaw. This bone is called suspensorium. A

skull in which suspensorium is formed by quadrate is called autostylic LESSER
skull e.g. frog skull. A skull in which suspensorium is formed by CORNU

squamosal is called craniostylic skull e.g. rabbit skull (all mammal).

(2) Hyoid arch (II pair of visceral arch) : It is also one pair of BODY

which is called Hyoid proper and Hyomandibular. Fig. – Human hyboid bone viewed from above
(i) Hyoid proper : It is a horse-shoe shaped bone in our neck

between lower jaw and sound box or larynx. It is not articulate to any bone but is simply suspended from temporal

bones by means of ligament. It consists of an elliptical main part or body and two

processes on each side of body, called greater and lesser cornua. It supports our

tongue and provides insertion to some tongue muscles. In colloboration with

branchial arches forms hyoid apparatus in terrestrial vertebrates. It is absent in

fishes because branchial arches form gill rackers which support gills.

(ii) Hyomandibular : It is second part of hyoid arch which constitutes ear

ossicles in vertebrate. In frog hyomandibular forms stapidial plate which is IIear

ossicle which is dot or lid like bone. In rabbit hyomandibular forms stapes which

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is III ear ossicle. That is stirrup like bone. Ear ossicles III
II Stapes
I Hyomandibular
Mallius Incus Sterip
Articular Quadrate
Hammer Anvil

(3) Branchial arches : These are five pairs, which constitute III to VII pair of visceral arches. These constitute

gill racker in fishes but terrestrial animals then form hyoid apparatus in collaboration with hyoid proper. Five pairs

of branchial arches are as follows –

(i) III pair ceratohyle.S.No. (ii) IV pair i.e. is epihyal. (iii) V pair i.e. is stylohyal.
(iv) VI pair i.e. tympanohyal. (v) VII pair i.e. thyrohyal.
c1.
NASAL PROCESS OF NN PREMAXILLA (U.J) HARD PALATE PALATINE PREMAXILLA
PREMAXILLA PROCESS OF PALATINE
MAXILLA (U.J) PREMAXILLA MAXILLA
NASAL PROCESS OF ZYGOMATIC
MAXILLA PROCESS OF PALATINE JUGAL
MAXILLA PROCESS OF PTERYGOID
SQUAMOSAL
JUGAL (U.J.) MAXILLA
ZYGOMATIC
FF PROCESS OF
SQUAMOSAL
EXTERNAL Sq P P Sq
AUDITORY INTER PARIETAL
AUDITORY
CAPSULE MEATUS

TYMPANIC So
BULLA

Fig. – Dorsal view of skull of mammal Fig. – Ventral view of skull of mammal

Difference between skull and frog of rabbit

Frog Rabbit

Skull somewhat triangular and dorsoventrally flattened; Skull longer than broad, not flattened, but bent in front

broader than long; not bent in the snout. in the snout.

2. Cranial skeleton not distinguished into cranial and facial Cranial skeleton distinguished into cranial and facial

regions; divisible into occipital, cranial and olfactory regions. Cranial region divisible into occipital, parietal

segments. and frontal segments.

3. Eye orbits form as depressions of skin and not as sockets Eye orbits form as sockets in skull; separated from each
in skull; separated from each other by cranial skeleton other only by a thin interorbital septum ( = tropibasic)
itself (platybasic)

4. Auditory capsules not lodged in cranial segment of skull; Auditory capsules lodged in cranial skeleton; each is

each is formed by a pro-otic bone. formed by a tympanic bone and reinforced by a

compound periotic bone.

5. Occipital segment small; has only two cartilage bones; Occipital segment large; has 4 cartilage bones around

the exoccipitals, around foramen magnum; no foramen magnum – dorsal supraoccipital, ventral

paroccipital processes. basioccipital and lateral exoccipitals having paroccipital

processes.

6. Brain box or cranium small due to smaller brain; mainly Brain box larger and more complex due to large brain;

consists of cylindrical sphenethmoid reinforced only by its posterior, parietal segment has two parietals dorsally,

three investing bones – two frontoparietals dorsally and two alisphenoids, laterally and one basisphenoid

one parashpenoid ventrally. ventrally; anterior, frontal segment has two frontals

dorsally, two orbitosphenoids laterally and presphenoid

ventrally.

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7. No prefrontal and lacrimal bones. These bones present.

8. Cranial cavity not anteriorly covered by cribriform plate. Cranial cavity anteriorly covered by a cribriform plate.

9. Vomers not fused together; bear vomerine teeth. Vomers fused medially; bear no teeth.

10. Olfactory capsules without turbinal bones. Olfactory capsules have turbinal bones.

11. Septomaxillary bones present. These bones absent.

12. Jaw wuspension autostylic. Jaw suspension craniostylic.

13. Premaxillac bear several small premaxillary teeth in two Premaxillae bear only two incisor teeth.
rows.

14. Maxillae bear a row of several small maxillary teeth. Maxillae bear only a few large cheek teeth.

15. Upper jaw has quadratojugal bones, but no jugals. Upper jaw has jugal bones but no quadratojugals.

16. Bones of upper jaw do not form zygomatic arches. Zygomatic processes of maxillae and squamosals,
Important Tips
together with jugal bones form zygomatic arches which
• Exoccipital and sphenethmoid bones are cartilaginous, sphenethmoid is unpaired bone.form outer borders of respective eye orbits.
• Pterygoid is the Y-shaped bone.
• Zygomatic arch is found in upper jaw and formed by maxilla, squamosal and jugal.17. Each squamosal bears a cartilaginous tympanic ring.Squamosals do not bear such rings.
• The bones common to face and cranium are frontal.
• Turbinal bones are present in the nasal passage.

c• Dermatocranium of skull comprises of membranous bone.
18. Lower jaw toothless; each ramus has an axis of persistent Lower jaw toothed; each ramus consists of a single large
Meckel's cartilage covered by two membrane bones – dentary bones bearing the teeth.
dentary and angulosplenial; Meckel's cartilage anteriorly
ossified into mentomeckelian.

19. Hyoid apparatus mainly formed of cartilage; none of its Hyoid apparatus mainly formed of bone; anterior cornua

cornua are jointed. are 4-jointed.

20. Skeletal elements in skull number – 46. Skeletal elements in skull number 53.

21. Quite a number of components of cartilaginous larval A few components of embryonic chondrocranium persist

skull persist in adult. in adult.

22. Foramina are few. Foramina more in number.

• Turbinals bones are present in the nasal passage and increase the sensory surface of olfactory chambers.

• Tympanic bulla enclosing the tympanus in mammal.

• Coronoid process is a part of lower jaw in mammalian skull.

• Lacrimal bone is situated infront of the eye orbit close to the frontal bone.

• Mastoid bone is found in auditory region.

• Frontoparietal is the membranous bone in frog.

• Anterior cornua of the hyoid apparatus of frog articulate with auditory capsule.

• Hyoid apparatus of frog is situated in the floor of pharynx.

• Sella turcica is found in base-sphenoid bone. It is a depression in skull which lodges the pituitary body.
• Amphibian & mammalia has dicondylic skull and reptiles, birds has monocondylic skull.

• Alar process is a part of hyoid apparatus.

• The hyoid apparatus of frog is entirely cartilaginous except posterior cornua.

• Septum axillary in the paired bone in frog.

• Pterygoid and palatines are paired bones on ventral side of skull of frog.

• Hammer shaped bone in skull of frog is squamosal.

• Pterygoid is membranous bone in frog skull.

• Frog has no basisphenoid bone.

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• Vomers is paired dorsal bone in frog skull.
• Lower jaw of frog includes mentomeckelian, dentary, angulo-splenial and meckels cartilage.

(2) Vertebral column : It is our backbone which extends in the mid axis of the back (posterior) part of our
trunk from head to the lower (inferior) extremity of trunk. Together with the sternum and rib, it forms the supporting
frame work of our trunk. It support and rotate the head, suspends the viscera, protect vital organs, provides
attachment to limb girdles, facilitates some movement of the trunk and houses the spinal cord.

Curvatures of vertebral column : In spite of the erect posture of body, the vertebral column of man is not
perfectly straight. It displays four curves to enhance balancing power and firmness for upright posture of body. The
curvatures are cervical, thoracic, lumbar and pelvic (=sacral). At birth, the whole column curves with the convexity
towards the back. By the time, the infant stands, this convexity persists only in thoracic and sacral regions. These
are called primary curvatures. A cervical curvature results from the effort on an infant to hold erect (3 to 4 months
old infant). A lumbar curvature results when the infant learns to walk during the age of about 10 to 18 months.
Cervical and lumbar curvatures are concave towards the back. Certain abnormalities of curvatures are –

(i) Kyphosis (Hunchback) : Exaggerated thoracic curvature.

(ii) Lordosis : Exaggerated lumbar curvature.

(iii) Scoliosis : A lateral curvature in any region.

• Vertebra column is formed by notochord.

• Notochord is characteristic of chordate and fundamental character of all chordates.

• It is present at any stage of life.

• It is a skeletal rod formed by chordal cells.

• In protochordate it persists throughout the life.

• It is a skeletal rod formed by chordal cells.

c• In vertebrates it is replaced by vertebral column.

• The vestegeal notochord called nucleus pulposes is found in intervertebral disc. Inter-vertebral disc is fibro
cartilagenous disc present between centrum of vertebrate.

(i) Typical structure vertebrae

(a) Neural arch : It arises from the dorsal side of the centrum and encloses a neural canal for the spinal cord.
The arch may be produced into a dorsal process, the neural spine, which may be elongated pointed or flattened
and directed upwards or backwards.

(b) Transverse processes : These are lateral extension of neural arch and centrum. There may be two types
of these processes – a more dorsal diapophysis arising from the base of neural arch and a lateral parapophysis
arising from the side of the centrum.

(1) Diapophysis (dia- two; apo- from; physis – growth) : These paired processes are directed differently
and provide attachment to the tubercular processes of ribs. They are commonly known as transverse processes and
are found in amphibians and other higher vertebrates.

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(2) Parapophysis : These paired outgrowths are similar to diapophysis and are common in fishes.

(3) Zygapophyses : These are paired and flat articular surfaces, which check the dislocation of the vertebrae.
These are the only structures which enable to identify the anterior and posterior faces of vertebra.

HYPAPO

NEURAL-SPINE METAPOPHYSIS NEURAL-SPINE
NEURAL ARCH PREZYGAPOPHYSIS POST-ZYGAPOPHYSIS

NEURAL CNAL DIAPOPHYSIS

TUBERCULAR
PROCESS
RIB

CAPITULAR PROCESS
(i) Prezygapophyses (Pre-before) : These are paired processes arising from the base of the neural arch onANAPOPHYSIS
the anterior face and are directed horizontally forward. The articular facets look upwards and inwards. These
structures are found almost in all vertebrae. ZYGANTRUM
DIAPOPHYSIS
(ii) Postzygapophyses : These are paired processes arising from the base of neural arch on the posterior face
and are directed horizontally backwards. The articular facets look downwards and outwards. They articulate over(TRANSVERSE PROCESS
the prezygapophyses of the following vertebra. OF AMPHIBIANS AND

c(4) Hypapophysis : It is a mid-ventral process which arises from the centrum. It may be directed forwards orHIGHER VERTEBRATES)
PARAPOPHYSIS HYPAPOPYSI
CENTRUM S

HYPAPOPYSI
S
ZYGOSPHENE

HAEMAL ARCH HYPAPOPHYSIS

HAEMAL SPINE HAEMAL CANAL CENTRUM PARAPOPHSIS
HYPAPOPYSIS (TRANSVERSE
PROCESS OF FISH)

Fig. – Hypothetical typical vertebra HYPAPOPYSIS
(front view)
Fig. – Hypothetical typical vertebra
(side view)

backwards as in certain reptilian, avian and mammalian vertebrae.

(5) Metapophyses : These are paired swellings or out growths having broad base and arising from just above

the prezygapophyses. They are directed forwards and upwards, but their articular facets look slightly downwards.
They are found in certain mammalian vertebrae.

(6) Anapophyses : These are paired, slender and short processes which arise just below the

postzygapophyses. Their articular facets look-slightly upwards and receive for the matapophyses.

(7) Heamal arch : It surrounds the haemal canal which allows the blood vessels of the tail region to pass. It

may be produced into a haemal spine below e.g. in fishes. The haemal PRO-COELOUS OPHISTHOCOELUS
arch of the caudal vertebrae of reptiles is called chevron bone. It is

usually Y-shaped. HETERO COELOUS ACOELOUS
(c) Centrum

The part of vertebra attached to second by centrum.

On the basis of centrum vertibrae may be of following type – AMPHI COELOUS

(1) Procoelus-vertebrae Fig. – Types of Centrum

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• Cavity is present on anterior side of centrum.
• It is present only in amphibia and reptilia.
• In reptilia is strongly and weakly procoelus is amphibia.
(2) Ophisthocoelus vertebra

• Cavity present on posterior side of centrum e.g. – Fishes, snake and crocodile only.
(3) Heterocoelus vertebrae

• Also known as SADDLE shaped vertebra. e.g. – Birds.
(4) Acoelus vertebrae

• No cavity in centrum so centrum is flat. e.g. – Mammals. c
• Also known as Amphiplatyon.
(5) Amphicoelus vertebrae

• Cavity present on both side of centrum e.g. – VIIIth vertebra of frog.
• All veretebrae of scoliodon (Dog fish)
(6) Amphidi condylar (Biconvex)

• Biconvex, condyle on both side. e.g. – IXth vertebra of frog.
• In frog IXth vertebra is Acoelus (i.e. cavity absent).
(ii) Vertebral column of man

• Made up of pieces of bones known as vertebrae.

• Vertebrae of man are acoelus i.e. Centrum is flat and
without cavity.

• Vertebral column also known as spinal column or
backbone.

• Number of vertebrae are thirty three (33) in vertebral
column.

• Cervical vertebrae are seven (7).

• Thoracic vertebrae are twelve (12).

• Lumbar vertebrae are five (5).

• Sacral vertebrae are five (5) in child but fuse to form
sacrum, caudal vertebrae are four (4) but form
coccyx in adult.

In the adult stage of man number of vertebrae are as follows –

Cervical (in neck) 7
Thoracic (in chest or thorax) 12
Lumbar ( in loins) 5
Sacral (in upper part of pelvis) 1 (formed of five fused vertebrae)
Coccygeal or Coccyx (in lower part of pelvis) 1 (formed of four fused vertebrae)

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(a) Atlas vertebra NEURAL ANTERIOR FACET FOR
• First cervical vertebra. CANAL ARCH
• Body is formed by centrum and vertebral arch. OCCIPITAL
• It supports the globe of the head like the earth by the FORAMEN CONDYLE
atlas (super man). TRANSVERSARIUM
• Centrum is absent. TRANSVERSE
• Neural spine reduced. PROCESS
• Transverse process are long.
Fig. – Atlas

(b) Axis vertebra GROOVE FOR
• Second cervical vertebra. TRANSVERSE LIGAMENT
• Centrum acoelus.
• Odontoid process present. OF ATLAS
FORAMEN
• It is pivot for rotation of atlas and head around odontoid
process. TRANSVERSARUM

TRANSVERSE
PROCESS

INFERIOR ARTICULAR
PROCESS
c5. Neuralforamen
• Transverse process small. Fig. – Man axis

Difference between Atlas and Axis vertebra

S.No. Characters Atlas vertebra Axis vertebra

1. Position First vertebra of vertebral column. Second vertebral of vertebral column.

2. Centrum Absent Present

3. Neural spine Absent Upward and bifuracated.

4. Pre and post Absent Pre-absent and Post present.
zygapophyses

Divided into upper spinal foramen and lower Not divided.

odontoid canal.

6. Odontoid process Absent Present

7. Function Supports the skull and yes movement of head. Supports rotatory and sideways movement of head.

(c) Cervical vertebra

ANTERIOR TUBERCLE FORAMEN
OF TRANSVERSE TRANSVERSARIUM
PROCESS POSTERIOR
TUBERCLE OF
TRANSVERSE
PROCESS

FORAMEN VERTIVRAL LAMINA
TRANSVERSARIUM FORAMEN

FORAMEN INFERIOR ARTICULAR BIFID SPINOUS
TRANSVERSARIUM PROCESS PROCESS

Fig. – Man cervical

Fig. – Man-VII cervical

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• Long neural spine.

• Centrum acoelus.

• Transverse process are large.

• Vertebrarteal canals present.

• Vertebrarteal canals also known as foramina transversia.

(d) Thoracic vertebra BONE DERIVED
• Centrum acoelus. FROM ANNULAR

EPIPHYSIS

VERTEBRAL
FORAMEN

TRANSVERSE
PROCESS
c•Neural spine well developed.• Neural canal is formed by union of two neural arches. PEDICLE
• Neural spine is a flat & long directed backward.
• Club shaped transverse process. PEDICLE
• Neural arch with superior articular process. Fig. – Man thoracic
• Two demifacets for articulation of head of a rib are present.

(e) Lumber vertebra

SPINOUS PROCESS SUPERIOR TRANSVERSE SPINOUS PROCESS
PROCESS LAMINA
LAMINA ARTICULAR PROCESS
SUPERIOR INFERIOR
INFERIOR ARTICULAR ARTICULAR
PROCESS PROCESS
ARTICULAR
PROCESS PEDICLE ACCESSARY
PROCESS
TRANSVERSE VERTEBRAL
PROCESS CANAL
PEDICLE
Fig. – Man Lumer
Fig. – Man IV lumber

• Centrum acoelus.

• Transverse process are thin and long.

• Small accessory process present near the root of each transverse process.

• It is the largest vertebrae.

Difference between Thoracic and Lumbar vertebra

S.No. Characters Thoracic vertebra Lumbar vertebra

1. Neural spine Long undivided and downward directed. Short, flat and upward directed.

2. Facet for ribs Present on transverse process and centrum. Absent.

3. Transverse process Club-shaped. Thin and elongated.

(f) Sacrum
• It is fusion of five vertebrae.
• Ventral curtualine increases pelvic capacity.
• Transverse process is much modified into a broad sloping mass project laterally from the body.
• Sacral canal is formed by sacral vertebral foramina.

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• In female sacrum is shorter and wider.

• In birds some of the vertebrae are fuse to form synsacrum. [Last thorasic+ Lumber+ Sacral+ One or two caudal]

(g) Coccyx

• It is formed by fusion of four caudal vertebrae.

• It is last section of backbone.

• It is small triangular bone.

• Two coccygeal cornua project up to articulate with sacral cornua.

• Rudimentary transverse process.

(3) Thoracic basket

(i) Ribs
cPROSTERNUM
(a) Structure : The ribs are curved bars, which movably articulate with the thoracic vertebrae at the back and

white with the sternum in front all collectively forming a bony cage, the thoracic basket. These are 12 pairs of ribs.

The upper seven pairs of ribs are attached in front directly to the sternum. These are called true rib. The next three

pairs of rib are jointed to the rib above each. They are termed false ribs. The lower two pair of ribs are free in front

they are known as floating ribs. Tenth rib is also usually floating in Japanese and some other people.

A rib consists of two parts – Vertebral and Sternal. The vertebral part is long and bony. It articulate with the

thoracic vertebrae by 2 facets, the capitulum and tuberculum, (Ribs of mammal and birds are bicephalous) in the

first nine ribs and by a single facet, the head in the remaining vertebrae. The sternal part is short and cartilaginous. It

articulate with the sternum or sternal part of its upper rib.

Human thorax is wider from side to side then from front to back. This is an adaptation for the up right posture

of the body. It help to maintain equilibrium. In birds a uncinate process is present in ribs for muscles attachment.

(b) Function : The ribs serve three important functions –

(1) They protect the heart, large blood vessels and lungs.

(2) They bear respiratory muscle (external and internal intercostal muscle). NON-ARTICULAR
PART OF TUBERCULE
(3) Lower two pair of ribs protect the kidney.

Ist THORACIC FACET FOR ANGLE
VERTEBRA CLAVICLE

Ist RIB NECK

MESOSTERNUM 2nd RIB ARTICULAR PART HEAD
OF TUBERCULE

STERNUM

COSTAL SHAFT
CARTILAGE
NON-ARTICULAR NECK HEAD
6th RIB PART OF TUBERCULE
ARTICULAR
METASTERNUM B FACET
7th RIB
8th RIB ARTICULAR FACET
9th RIB OF TUBERCULE
10th RIB
12th THORACIC 11th RIB PLACE OF
12th RIB VERTEBRA
ARTICULATION
Fig. – Bones of thorax (front view)
A WITH COSTAL
(ii) Sternum CARTILAGE
(a) Structure
Fig. – A typical rib of left side
A – Inferior aspect; B – Posterior aspect

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• It is bone of chest.

• It is absent in fish.

• It is associated with pectoral girdle in amphibia.

• In man it is made up of cervical manubrium (presternum), mesosternum and xiphoid process (Meta sternum).

• In male it is nearly 17 cm long.

• Manubrium is broad and thick.

• Mesosternum is made up fine sternabrae.

• Metasternum is represent by xiphisternum which is smallest broad and thin. In mammal a cartilagenous plate

attached with xiphisternu known as xiphoid cartilage.

• Sternum = manubrium + 5 sternabrae + xiphisternum.

(b) Function : The sternum has two function –
(i) Pectoral girdle
(a) Structure : Each half (Os innominate) of the girdle mainly(1) It takes part in the formation of the protective thoracic basket.
comprises a large, flattened and triangular cartilage bone, the
scapula (shoulder blade). The broader side has a narrow strip of(2) It plays a role in the respiratory mechanism.
cartilage called suprascapula. The dorsal surface of scapula has a
median longitutinal ridge called acromian spine, which successively
becomes more and more prominent towards the narrower end of

cscapula and then, projects beyond this end as a distinct acromian
(b) Appendicular skeleton : It forms the bony frameworks of limbs and their supporting girdles, and
includes 126 bones as follows –

1. Upper extremities 2. Lower extremities

Pectoral girdle 4 Pelvic girdle 2

Upper limbs (arms) 60 Lower limbs (legs) 60

(1) Girdles : The girdle give articulation to the limb bones. There are two types pectoral girdle (shoulder girdle) and
pelvic girdle (Hip girdle). Each girdle is made up of similar right and left halves (os innominate).

SUPERIOR CORACOID CLAVICULAR
ANGLE PROCESS FACET
ACROMION
SUPRASPINATUS PROCESS
OF SCAPULA
SCAPULA DELTOID
SPINE PROCESS

INTRASPINATUS GLENOID
CAVITY

process. Another prominent metacromian process projects OF SCAPULA SCAPULA

horizontally from the base of acromian process. At its narrow end,

the scapula is itself fused with an inwardly bent, knob like coracoid

process. A deep, cup like concavity the glenoid cavity is located at

the end of scapula close to coracoid process. The head of humerus INFERIOR
ANGLE
bone of upper arm fits in to this cavity. Another component of each

half of pectoral girdle is a long and slender, rod-like membrane Fig. – Scapula-Pectoral girdle

bone the clavicle, articulated with the acromian process. The other end of clavicle is connected with pre sternum by

means of an elastic ligament.

(b) Function : The pectoral girdle serves two functions –

(1) It provides articulation to the arm bones. (2) It affords attachment to certain muscles of the arm.

(ii) Pelvic (Hip) girdle

(a) Structure : It is located in the lower part of the trunk. It consists of 3 bones – upper ilium, lower ischium

and inner pubis, fused to form a stout hip bone, the innominate. Ventral wall of pubis has a small bone called

catyloid. Acetabelum is formed by ilium, ischium and pubis, but in mammals pubis is replaced by cotyloid bone.

Pubis symphysis is present in mammals. Below the acetabulum, the innominate has a large oval gap, the obturator

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foramen (ischio-pubic foramen) . The two innominate bones and sacrum together from a sort of bowel, the pelvis,
that supports the lower abdominal viscera. This is also an adaptation for upright posture of the human body. The
female pelvis is larger and has a broader front and larger bottom opening than the male pelvis. This is an adaptation
for childbirth. In man ischiatic tuburocity or siting bone is present in ischiam.

(b) Functions : The pelvic girdle serves the following functions –

(1) It provides articulation to the bones of the leg.

(2) It contributes to the formation of a bowel for the support and protection of adominal viscera.

(3) It transfers the weight of the body to the leg.

(4) It provides the attachment to certain leg muscles.

ILIAC
CREST
cPelvis OUTER LIP
OF ILIAC CREST

ILIUM POSTERIOR
GLUTEAL LINE
ILIOPUBIC ACETABULUM
(ILIOPECTINEAL)
ISCHIUM
EMINENCE

PUBIC
TUBERCLE

Fig. – Man-Male Pelvic PUBIS ISCHIAL
TUBERCOSITY
OBTURATOR
FORAMEN

Fig. – Man-Pelvic Girdle

Difference between Male and Female pelvis

S.No. Characters Male pelvis Female pelvis
1.
2. Nature of bones of pelvic girdles Heavier and longer Lighter and smaller
3.
Sacrum Less concave More concave anteriorly

Shallow, narrow and round Deep, wide and funnel-shaped

(2) Limb bones : Limb are two types fore limb and hind limb.
(i) Bones of fore limbs
(a) Structure
• It includes Humerus + Radius & ulna + Carpals + Meta carpals + Phalanges.
• Humerus is characterised by presence of deltoid ridges for the attachment of muscles.
• Distal end of humerus at the elbow joint is like pully and called trochlea. Its groove is called olecranon fossa
whose basal part is marked by a supratrochlear foramen for the passage of branchial artery and nerve.
• Humerus is characterised by arterial foramen.
• Head of the humerus articulate with glenoid cavity of pectoral girdle.
• Radius is smaller and ulna is larger.
• Styloid process is present in distal end of ulna.

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• Olecranum process is present in ulna.

• Olecranum notch is formed by ulna which is also known as sigmoid notch.

• Carpals are eight in number.

• Metacarpals are five in number, and phalanges are – fourteen, phalanges formula = 2, 3, 3, 3, 3.

(b) Special features : In the human arm, (1) The joints are more movable than in the forelimbs of animals
(2) Metacarpals form a wide palm and (3) Thumb is opposable. The differences in structure are correlated to the
differences in function. Animals use their forelimbs mainly for locomotion whereas man uses the arms for work (grasping).

(c) Function : Bones of the arms provide strength to make the arms effective in working with them.
c• It includes Femur + Tibia and Fibula + Tarsals + Metatarsals + Phalanges
SIGMOID NOTCH

HEAD GREATER TUBERCULE ULNA SCAPHOID-4
ANATOMICAL (TUBEROSITY) CAPITATE-2

NECK LESSER TUBERCULE TRAPEZOID-4
(TUBEROSITY) TRAPEZIUM-4

SURGICAL NECK

HUMERUS SHAFT ENLARGED VIEW

RADIUS

CORONOID LATERAL STYLOID HAND
FOSSA EPICONDYLE PROCESS
CAPITULUM
TROCHLEA

Humerus NORMAL

(ii) Bones of hind limbs
(a) Structures

• Femur is longest and strongest bone.

• Femur is known as bone of thigh.

• Greater trochenter, lesser trochenter are present in femur. Three trochenter present in femur.

• Patellar groove in found in distal end of femur.

• Fibula is smaller and associated with knee joint.

• Tibia is larger.

• Tarsal bones are seven.

• Metatarsals are five.

• Phalonges are fourteen.

• Phalonges formula = 2, 3, 3, 3, 3

• Patella form knee cap.

• Patella is formed by sesmoid bone. Sesmoid bone is also known as fubellae.

• Thumb of foot is called hollux.

• Ankle bones have 6 tarsals and arranged in three rows then Ist row have astragalus and calcanum in rabbit.

These are longest bone for adaptation of locomotion.

• Nutrient foramen present in Tibio-fibula bone.

• Tibio fibula is longest bone in frog.

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GREATER HEAD LATERAL CONDYLE
TROCHENTER OF TIBIA

NECK APEX CALCANEUS
HEAD OF
LOWER FIBULA TALUS – 6TH
TROCHENTER (FETAL) MONTH
TUBEROSITY
OF TIBIA NAVICULAR
MEDIAL

CUNEIFORM
APPEARS

SHAFT TIBIA FIBULA

FEMUR TIBIA-FIBULAcMAN FOOT

(b) Special features : All the bones of the legs are more massive than the bones of the arms because the

legs alone support the body on the ground and are used in locomotion. The broad feet provide an additional stable

support in the upright posture.

(c) Function : The bones strengthen the legs to bear body weight, to balance the body while standing and to
aid in locomotion.

Difference between Humerus and Femur

S.No. Characters Humerus Femur
1. Position
2. Head In upper arm of fore limb. In thing of hind limb.
3. Process on head
4. Shaft Fits in glenoid cavity Fits in acetabulum.
5. Lower end
Two tuberosities. Two trochanters.

With deltoid ridge. No ridge

With a pully-like trochlea having 2 epicondyles. With two condyles and an intercondylar groove.

Important points of skeleton

Total number of bones : 206 Bones

Skull : 29 Bones Facial region : 14 Bones
Cranium : 8 Bones Nasals : 2 Bones
Vomer : 1 Bones
Occipital : 1 Bone Terbinal : 2 Bones
Parietal : 2 Bones Lacrymal : 2 Bones
Frontal : 1 Bones Zygomatic : 2 Bones
Temporal : 2 Bones Palaline : 2 Bones
Sphenoid : 1 Bone Maxilla : 2 Bones
Ethmoia : 1 Bone Mandible : 1 Bones

Coccyx : Fusion of 4 caudal vertebrae Vertebral formula = 33 (General)
In boy : 5 sacral vertebrae
In adult : Only one sacrum C TH L S C
RIBS in man : 12 pairs
↓ ↓ ↓↓ ↓
True ribs : 7 pairs 7 12 5 5 4

Sacrum coccyx

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False ribs : 3 pairs In adult = 26 L S C
Floatting ribs : 2 pairs C TH

↓ ↓↓↓ ↓

7 12 5 1 1

Sacrum coccyx

Ear ossicles Vertebral column : 26 Bones

Mallus : 2 Bones Sternum : 1 Bone

Incus : 2 Bones Ribs : 24 Bone

Stapes : 2 Bones Pectoral girdle : 4 Bones

Hyoid : 1 Bone Pelvic girdle : 2 Bones

Fore limbs : 60 Bones (30 in each)
Hind limbs : 60 Bones (30 in each)
Total : 206 Bones
In child : Bones 300
INTERVERTEBRAL
Joints
cDISC
There are many articulations or joints present in the skeleton.

Joints are classified based upon their structure and the kinds of movements which they permit.

Three main types of joints are –

(i) Immovable joints (Synarthroses)

(ii) Imperfect movable joints (Amphiarthroses)

(iii) Perfect movable joints (Diarthroses) COMPACT BONE

SUTURE

MARROW
SYNOVIAL MEMBRANE

SYNOVIAL FLUID

FAT

LIGAMENT

SYNARTHROSES AMPHIARTHROSES ARTICULAR
Fig. – Three main types of joints DIARTHROSES CARTILAGE

(i) Immovable joints : No joint cavity, no movement possible. These joints include –

(a) Sutures : Found between skull bones, sutures are fixed or fibrous joints, articulating
bones are held together by white fibrous tissue.

(b) Gomphoses : Teeth in mandibles, present in premaxillary and maxillary bones.

(c) Shindylases : Ethmoid bone in vomer (one bone fits into slit in another).

(ii) Imperfect joints : Joints in which syanovial cavity is absent. Permit a small amount
of movement. Fibrocartilage is placed between the bones. These are cartilaginous joints e.g. –
Pubis symphysis, between bodies of the vertebrae, between the manubrium and the body of
sternum, sacroilliac joint in frog.

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(iii) Perfect joints : Syanovial cavity and ligaments are present. These are typical joints having articulate
surface and syanovial capsule. Syanovial fluid act as a grease in the joint e.g. –
Joints of elbow, ankle, wrist, hip, knee. Articular cartilage covers the surface of
articular bones. Articular cartilage of synovial joint is hyaline cartilage. Synovial
joints are surrounded by tubular articular capsule. The articular capsule consists of
two layers, outer fibrous capsule and inner synovial membrane. The synovial
membrane secretes synovial fluid which lubricates and provides nourishment to
articular cartilage. In old age stiffness of joints is due to the decrease in synovial fluid.

(a) Ball and socket joint : Also known as enarthroses. Ball of one bone
articulate in socket of another bone. e.g.- head of humerus and glenoid cavity of pectoral girdle, femur and
acetabulum of pelvis girdle, joint between incus and stapes.

(b) Hinge joint : Also known as gingulum. Movement is possible in one direction only. e.g. – Joint of mallus
and incus knee joint, albow joint, articulation joint of lower jaw, joint of phalanges of digits.

(c) Pivot joint : Also known as rotatoria and helps in turning movement. One bone is fixed and second
articulate. e.g. – Atlas and axial of skull rotate with axis vertebra also known as atlanto axial joint.

(d) Gliding joint : Also known as arthrodial, limited movement in all direction. e.g.- Tarsuls bones of ankle
zygapophysis of vertebrae. Radius and Ulna.

(e) Shaddle joint : It is ball and socket like joint but not developed fully. e.g. – metacarpal of thumb, and
carpals of hand.

cli

Characters, adaptation, types, movement and disorder of bones

(i) Characteristics of female's skeleton : In female's skeleton, (i) skull is lighter, (ii) shoulders are narrower
(iii) sacrum is shorter but wider, (iv) pelvis in wider, has a broader front and larger bottom opening to facilitate child
birth, and (v) coccyx is more movable than in male's skeleton.

(ii) Adaptations in skeleton for upright posture : Human skeleton shows many adaptive features for
upright posture –

(a) Foramen magnum is directed downward so that the head may rest vertically on the vertebral column.

(b) Four curves in the backbone keep the centre of gravity near the heels. This helps to maintain balance and
makes walking erect on two legs much easier.

(c) Thorax is wider from side-to-side than from front-to-back. This helps to maintain equilibrium.

(d) Bowel-like pelvis supports the lower abdominal viscera.

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(e) Metacarpals form a wide palm and the pollex is opposable. This make the hand a grasping organ to work with it.
(f) Leg bones are stronger than the arm bones as the femur carry the entire weight of the body in locomotion.
(g) Broad feet provide stability in the upright posture.
(h) The arches of the feet enable the body to move with a degree of springiness.
(i) Increased mobility of the neck to see all round.
(j) Increased skeletal height provides greater range of vision.
(iii) Types of bones : Bones are divided into 4 categories regarding their size and shape –

(a) Long bones, e.g., humerus of upper arm, radius and ulna of forearm, femur of thigh, and tibia and fibula of leg.

(b) Short bones, e.g., metacarpals of palm and metatarsals of instep, phalanges of fingers and toes.

(c) Flat bones, e.g., scapula of shoulder girdle, sternum, cranial bodies.

(d) Irregular bones, e.g., vertebrae, carpals of wrist and tarsals of ankle.

(iv) Bone movement : Movements of bones occur only at the joints. The movements are brought about by
contractions of skeletal muscles inserted onto the articulating bones by firm cords of white fibrous tissue called
tendons. Cords of yellow elastic tissue, termed ligaments, stabilise the joints by holding the articulating bones together.

(v) Disorder of skeleton and joints : Any violent movement, such as jump, fall or knock, may cause injury
to the skeleton. The injury can be of 5 types : sprain, dislocation, fracture, arthritis and slipped disc.

(a) Sprain : Sprain refers to injury to a joint capsule, typically involving a stretching or tearing of tendons or
ligaments. Unfortunately, both these structures have much poorer regenerative power than bone, and once
stretched often remain weak. Sprain is often considered a minor disorder, but it may become chronic.

(b) Arthritis or Aching Joints : Arthritis refers to inflammation of the joints. It is a common disease of the
old age. Its common symptoms are pain and stiffness in the joints. It has many forms. Three more common forms

care described here : osteoarthritis or degenerative arthritis, the rheumatoid arthritis and gout.
(1) Osteoarthritis : Secretion of the lubricating synovial fluid between the bones at the joint stops. The
smooth cartilage covering the ends of the bones at the joint stops. The smooth cartilage covering the ends of the
bones at the joint wears out due to years of use and is replaced by uneven bony spurs. The joint becomes inflamed,
its movement becomes painful, and its function is diminished. Such a stiffness or fixation of a joint is also called
ankylosis. The condition of osteoarthritis is more or less permanent. It is common in old persons, mainly affecting
weight bearing joints.

(2) Rheumatoid arthritis : It is a chronic painful inflammation of the synovial membranes of many joints
simultaneously. It usually starts in the small joints in the hand and progresses in centripetal and symmetrical
manner. In severe cases, it eventually results in crippling deformities. There may be other manifestations such as
fever, anaemia, loss of weight and morning stiffness. The rheumatoid arthritis involves erosion of joints. It usually
starts at the age of 20 – 40 years, but may begin at any age. It affects the women more often than the men. Rest
and exercise under medical advice may give relief.

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Differences between Osteoarthritis and Rheumatoid Arthritis

S.No. Osteoarthritis Rheumatoid Arthritis

1. Synovial membrane stops secreting synovial fluid. Synovial membrane becomes inflamed.

2. Mainly affects weight bearing joints. Usually starts at small joints in the hand and
progresses centripetaly.

3. Smooth cartilage at the joints wears off and replaced Joints get eroded.
by uneven bony spurs.

4. Function of the affected joint gets diminished. There is crippling deformity of the joints in volved.

5. Occurs in old age. Usually occurs at the age of 20-40.

(3) Gout : It is an inherited disorder of purine metabolism, occurring especially in men. Body forms excess
amounts of uric acid and the crystals of sodium urate are deposited in the synovial joints, giving rise to a severe
arthritis. It generally affects one or two joints only. It is very painful, particularly at night, and makes movement
difficult. Redness and tenderness may be noticed in and about the affected joint. Gout generally affects the great
toe. Occurrence of gout is related to diet. Persons suffering from gout should avoid meat. There is no cure for
arthritis. However, pain relieving (analgesic) drugs are available to give comfort.

(c) Osteoporosis

Meaning : Osteoporosis is reduction in bone tissue mass causing weakness of skeletal strength (G.osteon =
bone, poros = pore, osis = condition). It results from excessive resorption of calcium and phosphorous from the
bone. There is relatively greater loss or trabecular bone than of compact bone. There is relatively greater loss of
trabecular bone than of compact bone. This leads to vertical compression, or crush fracture, of the vertebrae (which
consist primarily of trabecular bone), and fracture of the neck of the femur (which has considerable trabecular bone).

Causes : Osteoporosis occurs in postmenopausal women and elderly men. It may result from defective
intestinal calcium absorption and menopause. Possible environment factors include smoking, excessive drinking,

cand decreased exercise. Osteoporosis is more common in women than in men, and in older than in middle-aged persons.
Symptoms : Symptoms of osteoporosis are pain in the bone, particularly the back, and vertebral crush,
usually in weight-bearing vertebrae (thoracic-8 and below).

Prevention : Preventive measures in high-risk patients include supplementary calcium and exercise, and, in
postmenopausal women, estrogen replacement therapy. Supplementary calcium and sex hormones decrease bone
resorption and may arrest or reduce disease progression.

(d) Dislocation : Dislocation is displacement of bones from their
normal positions at a joint, for instance, slipping out of the ball of one
bone from the socket of another bone into which it is fitted. Dislocation is
accompanied by pulling or even tearing of the ligaments. Dislocation also
tends to become chronic.

(e) Slipped disc : Slipped disc is a displacement of vertebrae and Fig. – Types of bone fracture
the intervertebral fibrocartilage disc from their normal position. It may

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result from mechanical injury or defects of ligaments holding the vertebrae together.

(f) Fracture : Fracture is a break of a bone. Fracture occurs rarely in children. The bones of children have a
large quantity of organic matter and are, therefore, very flexible and less likely to break. With advancing age,
mineral matter (calcium phosphate) is deposited in the bones. This decreases the organic matter, making the bones
hard and brittle. Thus, old people are more liable to fracture of bones.

Bones fractures are of many types –

(1) Green-stick fracture : It is mearly a crack. The bones remains partly intact.

(2) Simple fracture : Bone breaks completely into two parts which remain close to each other.

(3) Comminuted fracture : Bone breaks into more than two pieces.

(4) Compound fracture : Bone breaks completely but a fragment pierces out through the skin.

(5) Evulsive fracture : A small piece breaks off fully from the bone but remains attached to the ligament.
Fractures need surgical treatment for healing and should be promptly and properly attended to.

(g) Bursitis : Bursitis in inflammation of the bursae present in the joints. It is caused by physical injury or
constant pressure on a single joint for a long time.

Body muscles
In the body of all the multicellular animals muscles are found. The movement of the body takes place by these

muscles. If the muscles become weak, the functioning of the body become difficult. The muscles are capable of
contraction and relaxation, hence these are elastic.

A muscle can pull a part of the body by its contraction (shortening). It cannot push that part by relaxation
(elongation). Hence, the muscles are typically arranged in antagonistic (opposing) pairs, one muscle moves a body
part in one direction by its contraction and the other muscle moves that part in the opposite direction by its

ccontraction. Of course, when one muscle contracts, its opposing muscle relaxes. The principle of antagonistic

muscles is true of both vertebrate as well as invertebrate muscles. Animal movements depend upon interaction of
muscles and skeleton.

(i) Action of body muscles : As mentioned above, the body muscles are arranged in antagonistic
(opposing) pairs. One muscle of a pair moves a body part in one direction and the other in the opposite direction.
For example, the muscle named biceps brings the forearm toward the upper arm, and the muscle called the triceps
moves the forearm away from the upper arm. When biceps contracts to cause movement, the triceps relaxes to
allow that movement to occur and vice versa. Similar pairs of opposing flexor and extensor muscles occur at the
wrist, ankle and knee. The type of movement that
results from the contraction of a muscle depends
entirely upon the way the muscle is attached to the
levers of the skeleton.

(ii) Classification of body muscles : According
to the type of motion they cause, the muscles are

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divided into the following types. The muscles that act together to produce a movement are called synergists and the
muscle that act in opposition to each other are antagonists. The muscles that act most powerfully during any given
movements are called prime movers.

(a) Flexor and Extensor : Muscles that bend one part over another joint is called flexor. Extensor muscle is
antagonist of flexor muscle. The contraction of an extensor extends a joint by pulling one of the articulating bone
apart from another.

(b) Pronator and Supinator : The contraction of a pronator rotates the forearm to turn the palm downward

or backward. Supinator is antagonist of pronator. A supinator contracts to rotate the forearm and thus to make

palm face upward or forward. c

(c) Abductor and Adductor : An abductor contracts
to draw a bone away from the body midline. Muscle that
brings the limb away from midline is called abductor. An
adductor draws a bone towards the body midline. Muscles
that brings the limb towards midline is called adductor.
Abductor muscle is antagonist of adductor muscle. Abduction
is levation and adduction is depression.

(d) Protactor and Retractor : Protactor
muscle pulls the lower jaw, tongue and the head
forward. Retraction is opposite to protaction.
Retractor muscle draws the lower jaw, tongue and
the head backward.

(e) Inversion and Eversion : Turning of
feet so that the soles face one another in
inversion. Eversion is the opposite of inversion. In

this movement, the soles of the feet face laterally.

(f) Rotation : Rotation is term that indicates the partial revolving of a body part on the part's long axis.

(g) Arrector : Raises hairs of skin.
(h) Levator : Elevates a part of body.
(i) Depressor : Lowers a part of body.
(j) Agonistic : Opposed in action by another muscle.
(k) Antagonistic : Counteracts the action of another muscle.

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(l) Sphineter : Closes a natural orifice or passage.
(m) Constrictor : Causes constriction or squeezing.
The adductor and abductor, elevator and depressor, pronator and supinator, and sphincters and dilators are
all antagonistic muscles.

(iii) Important muscles

In man total no. of muscles : 639 muscles

Biceps and Triceps Fore arm

Gastroenemius Shank of leg

Gluteimaximus Buttock muscles

Movement and LocomotionOblique Eye muscles
Rectus Eye muscles
Movement is one of the most important characteristics of living organisms. Nonliving objects do not move. IfMaxillariesUpper jaw
nonliving objects show movement, that is always due to some external force. For example, the cart is moved by thePectoralis MajorChest
horse and the fan revolves by the energy of electric current. The movement of a nonliving object is, thereforePectoralis MinorChest
induced (due to external force) while the movement of living things are autonomic (self sustained). Study ofMandibularisMuscle of lower jaw
Latissisus dorsi Shoulder muscle
cmovement is called kinesiology (G. Kinein = to move, Logos = study). The movement of living systems are thusExternal obliqueLower abdomen
Internal oblique Lower abdomen
Transversus Lower abdomen
Rectus abdominus Lower abdomen
Stepedial muscle / arrector pilli Smallest muscle

autonomic or active, that is effected by the organisms themselves without external influences. On the other hand the

movement of nonliving systems are induced or passive, i.e. – made to occur by external forces. Movement of

animals are two main types muscular and non muscular.

(i) Muscular movement : Muscular movement are found in the majority of animals bought about by sliding
of myofilaments. Muscular movement are further divide into two kinds : Locomotion and movement of body parts.

(a) Locomotion (locus = place + moveo = to move) : Locomotion is the movement of an animal as a
whole from one place to another.

Types of locomotion : Locomotion takes several forms such as walking (man), creeping (earthworm, lizard),
hopping (frog, rabbit), running (dog, horse), flying (insects, birds) and swimming (fish, whale). Locomotion
distinguishes most animals from plants. The word 'most' has been used with animals because all animals do not
have the power of locomotion. Sponges, many coelenterates (Obelia) and tunicates (Herdmania) are sedentary, i.e.,
they live fixed to the substratum throughout life. However, even they show considerable movement of their body
parts, and their larvae are capable of locomotion (swimming) to bring about dispersal.

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Animals have suitable adaptations for their specific mode of locomotion. Adaptations for running, hopping,
swimming and flying are respectively called cursorial, saltatorials, natatorial, and volant adaptations.

Morphogenetic movement, i.e., the streaming of cells in the early embryo to form tissues or organs, may be
considered a form of locomotion.

Advantage of locomotion : Locomotion is helpful for animals as escape from predators, search of shelter,
food and water, shift to favourable environment, reproduction, collect materials for nest building, locate suitable
area for breeding and dispersal to new location. All forms of locomotion require energy to overcome two forces that
tend to keep the animals stationary. These are friction and gravity.

(1) Swimming : Water is a much denser medium than air so body modified for swimming in the form of
buoyancy, fusiform body etc. Mode of swimming varies in animals. fishes swim by moving their body and tail from
side to side. Whales and dolphins swim by undulating their body and tail up and down. Insects and 4-legged
vertebrates use their legs as oars to push against the water. Cuttle fish and squid are jet-propelled, taking in water
and squirting it out in bursts.

(2) Locomotion of land : For walking, running, hopping and crawling on land, animal expends energy body
to prevent falling down and move forward against gravity. Powerful muscles and strong skeletal support are more
important for moving on land than a streamlined body. Creeping animals have their entire body in contact with the
ground,. Therefore, they make a considerable effort to overcome friction.

(3) Flying : Gravity is a major problem in flight. Wings must produce enough lift to make and keep the animal
air-borne against the downward force of gravity.

(b) Movements of body parts : Movement of the body parts help the animals in several respects.
(1) Movement of external parts : Appendages are vary in number and form in different animals.
Many annelids have several pairs of flat parapodia, arthropids have 3 to many pairs of jointed legs, mollusks
have an unpaired foot, enhinoderms have numerous paired tube-feet, vertebrates have fins in fishes or limbs in all others.

cMovements of head, trunk and appendages, enable the animals to assume favourable posture for rest and

equilibrium. Movements of appendages, snout, mouth, jaws, tongue, etc., enable the animals to capture and ingest
food. Movements of sense organs, namely tentacles, antennae, eyeballs and pinnae of the ears, help the animals to
gather information about their external environment. Movements of buccopharyngeal cavity bring about water
breathing in fishes and air breathing in amphibians, and movements of chestwall cause ventilation of lungs in other
vertebrates. Movement of body parts also assist the animals in mating and feeding the young ones. Facial
expression and gestures also result from movements. Vibrations of vocal cords produce sound in vertebrates, and of
special abdominal plates in cicada. Rubbing the edges of forewings produces sound in grasshoppers.

(2) Movements of internal parts : Visceral movements make many vital activities possible :
• Heart beats circulate blood in the blood vessels.
• Peristalsis of alimentary canal propels food through it. Segmenting and pendular movements of gut help mix

digestive juices with food.
• Movements of diaphragm assist the chest in the flow of air through the respiratory tract.
• Peristalsis propels secretions and wastes through the ducts.
• Movements of genital tract effect egg laying and delivery of the baby.
• Visceral movements are also responsible for sound production, defaecation and micturition.

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(ii) Non-Muscular movement : Besides locomotion and movements of body parts, some of the cells of
multicellular animals move like unicellular organisms.

(a) Ciliary movement : The cilia present in the trachea, vasa efferentia and oviducts propel by their
movements dust particles, sperms and eggs respectively. The cilia of flame cells of flatworms push excretory materials.

(b) Flagellar movement : The flagella of choanocytes (collar cells) of the sponges maintain a regular current
of water in the body. The flagella of certain cells of gastrodermis of hydra help in the circulation of food. Sperms
move by flagellar movements.

(c) Pseudopodial movement : Leucocytes and macrophages move by pseudopodial movement.

(d) Cytoplasmic streaming movement : Streaming movement of the cytoplasm is called cyclosis. It is

observed in most of the cells.
cfrom one place to another by legs (walking) as by wings (flight) both.
(iii) Locomotion in different animals

(a) Locomotion in Protozoa : Locomotion in protozoans by the help of cilia, flagella and pseudopodia.

(b) Locomotion in Porifera : Sponges are sedentary or fixed animals which are always attached to some

substratum. Hence locomotion never takes place.

(c) Locomotion in Coelentrates : Locomotion in coelentrates is largely due to the contraction of the

epidermal muscle fibres following type of movements take place in coelentrates –

(i) Swimming (ii) Floating (iii) Surfacing (iv) Climbing (v) Walking

(vi) Gliding (vii) Somersaulting (viii) Looping (ix) Bending swaying movement.

(d) Locomotion in Helminths : In helminths (platyelminthes and aschelminthes) locomotion takes place by

body muscles, setae and buccal chamber.

(e) Locomotion in Annelids : Leech, Earthworm and Nereis have well developed circular and longitudinal

muscles in the body wall that help these animals to move about. The leech performs looking or crawling movement

on a substratum and swimming movement in water. Parapodia and setae helpful for locomotion in nereis.

(f) Locomotion in Arthropods : In arthropods locomotion takes place with the help of jointed legs, and a

pair of wings. The arthropods which cannot fly move with the help of jointed legs. Insects are capable of flying

because most of them possess a pair of wings in the thorax which help in flight. Cockroaches, housefly etc., move

(g) Locomotion in Mollusca : In all the molluscs, the locomotory organ is a thick walled, muscular, broad

or laterally compressed foot. In some molluscs, the foot is modified into eight or ten arms (e.g., Sepia, Loligo,

Ocotopus etc).

(h) Locomotion in Echinodermata : In echinoderms such as starfish, the locomotory organs are tubefeet

and locomotion takes place by water vascular system. The tubefeet are associated with this system intimately. At the

time of locomotion, one or two arms of a side work as main structures.

(i) Locomotion in vertebrates : In vertebrates, locomotion takes place with the help of skeletal muscles,

and skeleton. The locomotory organs are a pair of legs.

Important Tips

• Largest widest muscle – Gluteus maximus (Hip).

• Smallest muscle – Stapedius (Ear).

• Longest muscle – Sartorius (Leg).

• Calf muscle – Gastronemius (Shank muscle).

• Trijection muscle – Deltoid muscle.

• Hamstring muscle – Semi tendinous, semi membranous, bicip femoris. In players there is very common over stretching of these muscle.

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• Flying muscle – Pectoralis major and minor.
• Strongest muscle – Jaw muscle (Masseter).
• Smiling muscle – Buccalis.
• Fastest muscle – Muscles of eye lobs.
• Sartorius muscle – Flexation of thigh, knee and its rotation.
• Obtrator externus – Rotation of thigh an lateral side.
• Tensor tympani – Connects the malleus to the wall of the tympanic chamber in the ear of mammal.
• Hilton muscle is aryepiglotticus muscle.
• In children the bone are more flexible and brittle because their bone have large quantity of organic substances and little salt.
• Old people are more liable to fracture of their bone because bone become hard and brittle.
• In muscular hypertrophy cells increase in size by synthesizing the length of a myofibril.
• Presence of furcula in birds.
• Calcaneal process forms the heal in rabbit.
• Endoplasmic reticulum or sarcoplasmic reticulum play a major role during muscle contraction, muscle excitement and muscle relaxation.
• Fore limb is not found in birds.
• Skeleton absent in jelly fish.
• Urostyle present in caudal region of frog.
• Tail vertebrae of birds form pygostyle.
• Birds has pneumatic bone.
• Six typical vertebrae present in frog.
• Central shaft of a long bone is known as diaphysis.
• Curved bone is structurally designed to absorb the stress of the body weight at several different points so that the stress is evenly distributed.
• Tibio-fibula is the shank bone.

c• Joint between skull and atlas which allows nodding movement is called atlanto-occipital joint.

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Introduction
In all the multicellular animals above the level of sponges, the system meant to perceive stimuli detected by the

receptors, to transmit these to various body parts, and to effect responses through effectors, is called nervous
system. In vertebrates, it is highly specialized and plays at least three vital roles

(i) Response to stimuli : By responding to all sorts of stimuli, it acquaints the organism with them so that the
organism may react and orient itself favourably in the surrounding environment.

(ii) Coordination : Along with endocrine system, the nervous system also serves to coordinate and integrate
the activities of various parts of the body so that they act harmoniously as a unit. This makes possible the integrated
control of the internal body environment (homeostasis). However, the nervous system brings about rapid
coordination by means of nerves, whereas the endocrine system does so gradually and slowly by secreting
hormones into blood.

(iii) Learning : By accumulating memories from past experiences, in higher vertebrates at least, the nervous
system serves as a centre for learning. The branch of medical science dealing with the structure (anatomy), functions
(physiology) and diseases (pathology) of nervous system is called neurology.

Nervous system in various animals
(i) Coelenterata : True nerve cell or ganglion cells occur for the first time in coelenterates. They are derived

from interstitial cells of epidermis, forming nerve net or nerve plexus below whole epidermis.

(ii) Platyhelminthes : Nervous system of planarians marks the beginning of a centralized nervous system
encountered in higher animals. That is made up of brain or cerebral ganglia, two lateral longitudinal nerve chords,
numerous peripheral nerves and transverse commissures or connectives. This is sometimes called the ladder type of
nervous system. In addition to the centralized nervous system planaria also possesses a sub-epidermal nerve net like
that of coelenterates. Brain receives stimuli from the sense organs and conveys them to different parts of body.
Special receptors, as found in turbellarians, are lacking in tapeworm. However numerous free sensory nerve-
endings are present throughout the body specially in the scolex.

cIn Nematoda (e.g. ascaris) these system made up of central nervous system, peripheral nervous system and

rectal nervous system. Rectal nervous system more developed in male.

(iii) Annelida : Nervous system well developed and concentrated. It consists of three parts : central nervous
system, peripheral nervous system and sympathetic nervous system, central N.S. made up of Nerve ring and ventral
nerve cord. Nerves are of mixed type, consisting of both afferent (sensory) and efferent (motor) fibres.

(iv) Arthopoda : The nervous system of prawn or arthopods is of the annelidan type. However it is
somewhat larger and has more fusion of ganglia. It consists of (i) The central nervous system including brain
connected with a ventral ganglionated nerve cord through a pair of circum-oesophageal commissures, (ii) The
peripheral nervous system including nerves and (iii) The sympathetic nervous system.

(v) Mollusca : In gastropodes (e.g. pila) consists of paired ganglia, commissures and connective uniting them
and nerves running from these central organs to all parts of the body. It has various type of ganglia as cerebral,
buccal, pleuro-pedal, supraintestinal and visceral etc. In palecypoda nervous system is greatly reduced due to
sluggish and sedentary mode of life and there is little evidence of the brain. But in cephalopoda shows a high grade
of organization attained only by some insects and arachnids among the other invertebrates.’

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(vi) Echinodermata : Echinodermates has simple and primitive type nervous system. It has the form of a
nerve net, consisting of nerve fibres and a few ganglion cells, all confined to the body wall except the visceral nerve
plexus situated in the gut wall. At certain places the nervous tissue is concentrated to form distinct nerve cords. It is
made up of (i) Superficial or ectoneural nervous system (ii) Hyponeural or deep nervous system (iii) Aboral or
coelomic nervous system and (iv) Visceral nervous system.’

(vii)Hemichordata : Nervous system is of primitive type resembling that of coelenterates and echinodermates.

Chordates : Nervous system well developed and formed by ectoderm. It is formed by CNS, peripheral
nervous system and autonomous N.S.

OLFACTORY LOBE

c(RHINENCEPHALON)
Development of central nervous system in human

The central nervous system of vertebrates includes the brain and the spinal cord. These are derived from a
longitudinal mid-dorsal ectodermal thickening of the embryo, called the meduallary or neural plate. This neural
plate or neural groove is converted by fusion into a closed mid-dorsal longitudinal neural tube lying above the
notochord. Histologically, the embryonic neural tube exhibits three zones of cells.

ENCEPHALON FOREBRAIN HINDBRAIN
(PROSENCEPHALON) (RHOMBENCEPHALON)

SPINAL CORD ECTODERM NEURAL PLATE NEURAL GROOVE NEURAL FOLD

SPINAL CORD

A MID BRAIN B

(MESENCEPHALON) NEURAL CREST
PINEAL BODY OPTIC LOBES
CEREBELLUM A NOTOCHORD B
PARIETAL BODY (METENCEPHALON) ECTODERM NEURAL CREST GANGLION
NEUROCOEL
CEREBRUM MEDULLA OBLONGATA NEURAL
(TELENCEPHALON) (MYELENCEPHALON) TUBE

PALLIUM

SPINAL CORD

CRUS CEREBRUM

CORPUS STRIATUM DIENCEPHALON C C NOTOCHORD D
OPTIC CHIASMA THALAMUS

HYPOPHYSIS PITUITARY INFUNDIBULUM Fig. – Stages in the embryonic development of central

BODY nervous system inT.S.

Fig. – Stages in development of brain. A – Anterior end of neural tube in
lateral view. B – M.L.S. of embryonic brain to show three primary
cerebral vesicles. C – Differentiation of brain from three vesicles.

(i) Germinal layer : These are actively dividing cells lining the neural canal. They form the connective tissue
lining of neural canal, called ependyma, and also proliferate into mantle layer cells.

(ii) Mantle layer : It consists of embryonic neurons or nematoblasts, forming the gray matter.

(iii) Marginal layer : It consists of nerve fibres, mostly surrounded by fatty myelin sheaths, and forms the
white matter. Neurons and fibres are supported by a special connective tissue of ectodermal origin, the neuroglia,
cells of which become increasingly abundant and diversified in higher vertebrates.

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Development of brain : The anterior end of embryonic neural tube is already enlarged forming the embryonic

brain, called encephalon. By differential growth and OLFACTORY LOBES RHINENCEPHALON

two constrictions, it is divided into a linear series of FORE BRAIN CEREBRAL TELENCEPHALON
three primary cerebral vesicles, termed the forebrain, HEMISPHERES

midbrain and hindbrain. These give rise to the three PROSENCEPHALON

major divisions of the adult brain – (1) PINEAL BODY DIENCEPHALON

prosencephalon (forebrain), (2) mesencephalon INFUNDIBULUM

(midbrain), and (3) rhombencephalon (hindbrain). MID OPTIC LOBES MESENCEPHALON
BRAIN

These further become subdivided into 5 subdivisions. CEREBELLUM METENCEPHALON

The various parts of the adult brain in different HIND MEDULLA OBLONGATA MYELENCEPHALON
vertebrates are formed by modifications. That is, by BRAIN
thickenings and foldings of these 5 subdivisions. The
adult brain has a series of cavities, called ventricles,
which are in continuation with the central canal of the
spinal cord and filled with a cerebro-spinal fluid.
Parts of nervous system SPINAL CORD

Nervous system is divided into three parts ABC
Fig. – Pattern of generalized vertebrate brain. A – Lateral view.
(i) Central nervous system (CNS) : In all the vertebrates including man, CNS is dorsal, hollow and non-
ganglionated while in invertebrates when present, it is ventral, solid and ganglionated. CNS is formed of two parts :B – Dorsal surface. C – H.L.S. showing ventricles
Brain – Upper and broader part lying in the head; and Spinal cord – Lower, long and narrow part running from
beginning of neck to trunk. Nervous system

(ii) Peripheral nervous system (PNS) : It is formed of long, thin, whitish threads called nerves which
extend between CNS and body parts (muscles, glands and sense organs). It controls the voluntary functions of the
body. It has cranial and spinal nerves.

(iii) Autonomic nervous system (ANS) : It is formed of nerve fibres extending upto visceral organs and
controls the involuntary functions of visceral organs of body like heart beat, peristalsis etc. It is again formed of two

csystems: sympathetic and para-sympathetic nervous system which have opposing functions.
Central Nervous System (CNS) Peripheral Nervous System (PNS) Autonomic Nervous System (ANS)

Brain Spinal cord Cranial Nerves Spinal Nerves Sympathetic Parasympathetic
(All Mixed) Nervous System Nervous System

Sensory Nerves Motor Nerves Mixed Nerves
(III, IV, VI, XI, XII) (V, VII, IX, X)
(I, II, VIII)

(i) Central nervous system : Central nervous system is made up of brain and spinal cord. CNS is covered

by 3 meninges and its wall has two type of matter.

Types of matter : CNS of vertebrates is formed of two types of matter –

(a) Grey matter : It is formed of cell-bodies and non-medullated nerve fibres.

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(b) White matter : It is formed of only medullated nerve fibres which appear white due to presence of
medullary sheath.

Meninges : The meninges are connective tissue membranes which surround the brain and spinal cord of CNS.
In the fishes, there is only one meninx called meninx primitiva. In amphibians, reptiles and birds, the brain is
covered by two meninges or membranes : inner pia-arachnoid and outer dura mater. In mammals, CNS is covered
by three meninges or membranes

(a) Duramater (Dura = tough; mater = mother): Outermost, thick, fibrous, 2-layered meninge. The outer

layer adheres to skull at many places while the inner layer follows the major convolutions (sulci and gyri) of the

brain and spinal cord. Meningeal artery traverses via duramater. The two layers of duramater are widely separated
(c) Piameter (Pia = soft = tender) : This is the innermost meninge and follows the convolutions of the
outer surface of brain and spinal cord. It is highly vascular and penetrates deeply in certain places bringing it with itsat some places to form the large sinuses calledFIBROUSDURAMATER
venous sinus. This drains deoxygenated (= venous) CONNECTIVE
cvasculature and placing it in contact with the ventricles of the brain and neurocoel of spinal cord.blood from the brain to the large veins that return itARACHNOID
to the heard. The space between duramater and the TISSUE
next meninge in succession is called sub-dural
space is filled with cerebrospinal fluid and has OUTER DURAMATER
arachnoid villi in the region of dural space.
Similarly the space between the skull and SEROUS MIDDLE ARACHNOID
durameter is called epidural space. Duramater MEMBRANE
extends in the form of straight sulcus between cerebrum (RECTICULAR INNER PIAMATER
and cerebellum posteriorly. Here it is called tentorium. CONNECTIVE

TISSUE

PIAMATER

(AREOLAR HIGHLY SKULL
VASCULARISED TISSUE) Fig. – Meninges of brain

(b) Arachnoid (= spider-like web) : It is closely related to duramater on its outside and with piameter on the
inside. The space between the arachnoid and piameter is called sub-arachnoid space and is filled with cerebro-spinal fluid.

Cerebrospinal fluid : All the ventricles of the brain are continuous and lined by a columnar, ciliated
epithelium, the ependyma. They contain lymph-like extracellular fluid called the cerebrospinal fluid (C.S.F.). This
fluid is secreted by the choroid plexuses by filtration of blood. The choroid plexuses consist of loose connective
tissue of pia mater covered internally by a simple cuboidal epithelim of secretory (glandular) nature. The
cerebrospinal fluid slowly flows toward the fourth ventricle by secretion pressure and passes into the spinal cord.
Some fluid escapes into the subarachnoid spaces through three pores in the roof of the fourth ventricle in the
medulla. From the subarachnoid spaces, the cerebrospinal fluid is transferred to the blood of the venous sinuses. Nervous
tissue is without lymphatic vessels.

The cerebro-spinal fluid (CSF) provides

(a) Protection to brain from mechanical socks.

(b) Optimum physiological fluid environment for neural functions e.g. conduction of nerve impulses, transport
of aminoacids, sugars, O2 etc.

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(c) ‘Relief’ mechanism for the increase in intracranial pressure that occurs with each arterial pulse of blood to brain.

(d) ‘Sink’ like facility for metabolites of brain.

(e) The blood CSF barrier for selective transport process between blood and CSF.

Major site of CSF formation is choroid plexus, and mid ventricular wall and sub-arachnoid wall also
contribute. CSF is cell free, slightly alkaline, and is isotonic to plasma. Rate of formation of C.S.F is 80 ml/hour
approx, 1/2 litre per day. Total amount present in and around CNS is 150 ml it means there is atleast 3 times
renewal of C.S.F. every day.

Blood brain barrier facilitate maintenance of stable internal environment. Its acts as physiological and
pathological barrier as well. Hydrocephalus : The enlargement of head, a pathological condition characterized by
an abnormal accumulation of cerebrospinal fluid resulting headache, vomiting, pain and stiffness of the neck.

• Increased cerebrospinal fluid may result Meningites.

• Meningites may appear due to infection and inflamation of meninges or injury of meninges.

• Infection may be viral, bacterial or both. The most common cause of meningitis in the infection of
streptococcus and neumoniae, neisseria meningitidis and haemophilus influenzae.

• Lumber puncture is done for drainage of excess of cerebrospinal fluid during meningitis.

• Cerebro-spinal fluid is formed by choroid plexus (ACP and PCP).

There are three choroid plexus in humans

(a) Lateral choroid plexus : It is in the roof of I and II ventricle.

(b) Anterior choroid plexus : It is in the roof of III ventricle (diacoel).

c(c) Posterior choroid plexus or pelochoroida : It is in the roof of IV ventricle.
Oxygen and glucose requirements : Brain controls the functions of our body organs and also provides the
qualities of mind – learning, reasoning, and memory. For these activities, brain needs a large and constant energy
supply. At any given time, the activities of the brain account
for 20% of the body’s consumption of oxygen and 15% of its CEREBRUM
consumption of blood glucose. Brain deprived of oxygen for
just 5 minutes is permanently damaged. Mental confusion
results if brain is deprived of glucose.

(a) Brain (Encephalon) : It is soft, whitish, large sized SULCI PONS MEDULLA CEREBELLUM
and slightly flattened structure present inside cranial cavity of GYRI SPINAL
cranium of the skull. In man, it is about 1200-1400 gm in CORD
weight and has about 10,000 million neurons. Brain is made
up of 3 parts

(1) Fore brain (Prosencephalon) Fig. – Main parts of human brain visible from lateral view

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(i) Olfactory lobe – Rhinencephalon

(ii) Cerebrum – Telencephalon

(iii) Diencephalon – Diencephalon

(2) Mid brain (Mesencephalon)

(i) Optic lobes – Mesencephalon

(3) Hind brain (Rhambencephalon)

(i) Cerebellum – Metencephalon

(ii) Medulla oblongata – Myelencephalon
limbic. A lobe called insula is hidden as it lies
deep in the sylvian fissure. The cerebral

chemisphere are separated from olfactory lobes
(1) Fore brain or Prosencephalon : It forms anterior two-third of brain and is formed of three parts.

(i) Olfactory lobes : These are one pair, small sized, club-shaped, solid, completely covered by cerebral
hemisphere dorsally. Each is differentiated into two parts –

(a) Olfactory bulb : Anterior, swollen part, and

(b) Olfactory tract : Posterior and narrow part which ends in olfactory area of temporal lobe of cerebral
hemisphere.

Function : These control the smell.

• It is normal in frog, rabbit and man.

• It is well developed in dog. So power of smell is more in dog.

• These are also well developed in dog fish and name dog fish is on the basis of well developed olfactory lobes.

(ii) Cerebrum : (a) Structure is divided into 5 lobes (i) frontal (ii) parietal, (iii) occipital, (iv) temporal and (v)

HUMAN BRAIN PARIETAL
LOBE
FRONTAL LOBE
GYRUS

by rhinal fissure. The median fissure divides SULCI
CORPUS
the cerebrum into a right and a left cerebral

hemisphere. TEMPORAL LOBE CALLOSUM
HYPOTHALAMUS PINEAL
A few sulci are well developed and form GLAND
three deep and wide fissures which divide PITUITARY GLAND
CEREBRAL PEDUNCLE OCCIPITAL
LOBE

each cerebral hemisphere into four lobes : CEREBELLUM

anterior frontal lobe, middle parietal lobe, PONS.

posterior occipital lobe and lateral temporal MEDULLA OBLONGATA

lobe e.g. Fissure lying between the frontal and

parietal lobes is central fissure, that lying Fig. – Sagittal section of human brain

between the parietal and occipital lobes is parieto-occipital fissure and that demarcating frontal and parietal lobes

from the temporal lobe is lateral or Sylvian fissure. Each cerebral hemisphere is with a fluid-filled cavity called lateral

ventricle or paracoel.

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FRONTAL LOBE CENTRAL SULCUS PARIETAL LOBE CEREBRAL (=MEDIAN) CORPUS
LIMBIC LOBE FISSURE CALLOSUM

PARIETO- LATERAL
VENTRICLE
OCCIPITAL-
SULCUS INTERNAL
CAPSULE

OCCIPITAL INSULA

LOBE CORPUS STRIATUM TEMPORAL
LOBE
LATERAL TEMPORAL + GLOBUS PALLIDUS
FISSURE LOBE = BASAL GANGLION

Fig. – Medial surface of cereberal hemisphere Fig. – Cross section of cerebrum
c(b) Histology of cerebrum : The whole brain
Two cerebral hemispheres are interconnected by thick band of transverse nerve fibres called corpus callosum.

The peripheral portion of each cerebral hemisphere is formed of grey matter and is called cerebral cortex, while

deeper part is formed of white matter and is called cerebral medulla. Cerebral cortex is the highest centre for many

sensations and activities and is with a number of sensory areas.

Important areas in the human brain

Area Location Function

Premotor area Frontal lobe The highest centre for involuntary movements of muscles and ANS.

Motor area Frontal lobe Controls voluntary movements of the muscle

Broca’s area Frontal lobe Motor speech area

Somesthetic area Parietal lobe Perception of general sensation like pain, touch and temperature

Auditory area Temporal lobe Hearing

Olfactory area Temporal lobe Sense of smell

Wernicke’s area Temporal lobe Understanding speech written and spoken

Gustatory area Parietal lobe Sense of taste

Visual area Occipital lobe Sensation of light

possess grey matter outside and white matter inside GENERAL SOMAESTHETIC
AREA
MOTOR AREA
around ventricle.
GUSTATORY AREA

(1) Grey matter : In cerebrum grey matter is SPEECH AREA VISUAL AREA
very much developed, it is on an average 3.5 mm. SPEECH AREA
thick but at poles its thickness is 1.3 mm. It is OLFACTORY (READING/LANGUAGE)
thickest at pre central gyrus (4.5 mm thick). Grey AREA
CEREBLLUM

matter of cerebrum is called cortex or pallium. PONS VAROLI
Phyllogenetically or evolutionarily cortex is divided

into 3 parts – SPINAL CORD

(i) Allocortex or paleocortex : It is the MEDULLA
cortex of olfactory area of frontal lobe and olfactory
Fig. – Sensory areas of human brain

bulbs. In lower vertebrates (cartilagenous fish) olfact lobes occupy most of the part of cerebrum. So in these animals

sense of olfection is very-very much developed. Sense of olfaction is oldest sense.

(ii) Mesocortex : It is relatively not much older in development.

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(iii) Neocortex or neopallium or isocortex or neencephalon : It is most recent cortex and is developed
maximum only in human. It is in prefrontal cortex or prefrontal region (organ of mind), precentral and precentral

gyrus etc. The neocortex is having 6 (six) layer of neurons while remaining cortex possess only 5 layers.

The cerebral cortex is having area of about 2200 cm2 while the cranial cavity is only 1450 cm3, so to

accomodate cerebrum there appears foldings in the cortex. The ridges are called gyrus (or gyri) or convolution while

the depression are called sulcus (sulci in plural).

(2) White matter : It is inner part of brain. Its fibres are divide into 3 GYRUS

categories – SULCUS

(i) Commissural fibers : These neurons connect gyri of 2 hemispheres, CORTEX
ganglia is the name given to many sub cortical structure
such as corpus callosum. habenular commissure, anterior commissure, posterior
of walls of paracoel, hypothalamus and mid brain –
commissure. SUB CORTEX
(i) Corpus striatum : Corpus striatum is the(ii) Associate fibres : They connect gyri of same hemispheres.WHITE MATTER
name given to caudate nucleus and lenticular nucleus.
(iii) Projection neuron : They are infact assending and descending nerve
cCaudate is tail shaped while the lenticular nucleus is
tract, they connect one part of brain to another part of brain or to spinal cord. (In spinal cord they were called as

columo).

(c) Associated structures of cerebrum :

Cerebrum has following specific structure.

(1) Sub cortex : Nuclei on white matter. It is V1 V2 CAUDATE
cluster of grey neurons in depth of white matter, they NUCLEUS
are formed in whole brain and are named differently.
THALAMUS

(2) Basal granules or central nucleus : Basal CLAUSTRUM

INSULA

V3 PUTAMEN
LENTICULAR
NUCLEUS
GLOBUS

PALLIDUS

PITUITARY
BODY

lenti shaped. The lenticular nucleus is sub-divided in putamen (outer shell) and globus pallidus (ball).

(ii) Claustrum : It is the name given to grey matter present between insula and patamen.

(iii) Epistriatum or Amygdaloid body : It is structure present at the end of caudate nucleus.
(iv) Red nucleus and substantia nigra of mid brain.

The basal ganglia controls automatic movements of skeletal muscles like swinging, walking etc.

(3) Corpus callosum : It is the band of white neurons present between both cerebral hemisphere and

connect them on medial surface. It is present only mammal. It

has anterior part genu, middle part trunchus and last part TRUNCUS

splenium. GENU SPLENIUM
Below corpus callosum there are two fused band of

white neurons called fornix. There anterior part is called SEPTUM CRURA
PELLICIDUM FORNIX
column and posterior part is called crura. Between column
COLUMN

and genu a membrane is called septum lucidum or septum ROSTRUM

pellicidum. Septum lucidum encloses a space called V5 or

Pseudocoel, because it is not possessing C.S.F. i.e. why it is called pseudocoel.

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(4) Limbic system : It is also called emotional brain or animal brain. Limbic system controlling emotion,

animal behaviour like chewing, licking, sniffing,

rage, pain, plessure, anger, sexual feelings, STRAE MEDULARIS

grooming. It has following structure OCCIPITAL MAMILLARY BODY
(i) Singulate gyrus : It is a region of pre CAUDATE NUCLEUS

central gyrus. SIGNATURE GYRUS

(ii) Hippocampal gyrus : It is a region of
temporal lobe near colossomarginal sulcus.
These two structure are combinely called limbic HIPPOCAMPAL OLFACTORY BULB
FRONTAL

AMYGDALOID BODY

lobe. GYRUS

(iii) Amygdaloid body : It is the end ofc(vi) Diencephalon cavity is called, III vertricle or diacoel : The thin roof of this cavity is known as theDENTATE
caudate nucleus. GYRUM

(iv) Olfactory bulb : They are on the inferior anterior surface of brain. Olfactory nerve ends in these bulb.
(v) Mammillary body : They are found in hypothalamus. Olfactory bulb and mammillary body both are centre of
olfaction.

From a evolutionary point of view, the cerebral hemisphere are the highly evolved structure and this is

manifested by

(a) Great increase in the number of feed back circuits between cerebral cortex and sub cortical elements.

(b) The ability of man and other primates to perform variety of complex function.

(c) The lobe of cerebrum are delineated by fissure and sulci.
(d) A corpus callosum connects the left and right cerebral hemisphere. This is a unique property of mammals

as it facilitates flow of information between the 2 hemispheres.
(e) The cortical layer of cerebrum is thrown into folds (= gyri) separate by sulci. All the larger mammalian

brains exhibit well developed gyri. The degree of convolutions of the cortex is a fairly reliable indicator of the

evolutionary stages of development of brain. The roof of cerebrum is called pallium while the ventrolateral walls are

thick and are called corpora striata.

epithalamus, the thick right and left sides as the thalami, and floor as the hypothalamus.

(a) Epithalamus : The epithalamus is not formed of nervous OPTIC CHIASMA
tissue. It consists of piamater only. Hence, it is of relatively little
significance as a nerve centre. Its anterior part is vascular and folded. PINEAL BODY
It is called anterior choroid plexus. Behind this plexus, the PINEAL STALK
epithalamus gives out a short stalk, the pineal stalk which hears a
small, rounded body, the pineal body, at its tip. ANTERIOR CHOROID
PLEUXES

(b) Thalami : A pair of mass of grey matter formes the major DIOCOEL OPTIC THALAMI
part of the wall and floor of diancephalon. Its nuclei have complex HYPOTHALAMUS
connection with the sensory area of the cerebral cortex. It receives
and integrates sensory impulses from the eye, ear and skin. It has LAMINA INFUNDIBUIUM
nerve connection with motorcortex and act as relay centre. Habenular TERMINALS PITUITARY (HYPOPHYSIS)
commissure is a band of nerve fivers connecting two thalami. On the
Fig. – Diencephalon

inferior surface of each thalamus there are two rounded bodies of grey matter.’

(1) Median geniculate body (M.G.B) : It receives hearing impulse and relay into cerebral cortex.

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(2) Lateral geniculate body (L.G.B) : They are concern with vision EPITHALAMUS
(optic nerve) and relay visual impulse towards cerebral cortex.
THALAMUS
(c) Hypothalamus : The hypothalamus is visible in the ventral view

of the brain and forms the floor of diencephalon. Hypothalamus also gives a M.G.B.
nervous process called infundibulum (forms pars nervosa) which meets a L.G.B.
rounded non-nervous pharyngeal outgrowth called hypophysis. Both
collectively form master gland called pituitary body. A stalked outgrowth PINEAL
BODY

of infundibulum combines with a pouch-like epithelial outgrowth (Rathke’s CEREBELLER
pouch) of the roof of embryonic mouth (= stomodaeum), forming a PEDUNCLE

pituitary gland or hypophysis. Which secretes a number of hormones. In cFig. – Posterior aspect of brain
front of hypothalamus, there is cross of two optic nerves called optic
chiasma. Behind the hypothalamus, there is one pair of small, rounded, LONGITUDINAL
nipple-like bodies called mammilary bodies or corpora mammillares. The FISSURE
hypothalamus consists of many masses of grey matter,
called hypothalamic nuclei, scattered in the white matter.

In man and some other mammals, most fibres of OLFACTORY BULB FRONTAL HYPOPHYSIS
optic nerves cross, but some fibres do not cross and OLFACTORY LOBE INFUNDIBULUM
innervate the eyes of their own respective sides. This
arrangement enables man and these mammals to have a TRACT PONS TEMPORAL CEREBRAL
binocular vision. Rabbits simply have a monocular LATERAL LOBE PEDUNCLE
vision. FISSURE
MEDULLA
Pineal gland is a pine cone-shaped gland. It is OPTIC
located in the center of brain with which it loses all nerves CHAISMA MEDULLA
connection after birth. It is innervated by sympathetic OCCIPITAL LOBE
nerves. It has a photosensory role in amphibian and MAMMILLARY
primitive reptiles and is called ‘Third eye’. Pinealocytes BODIES
secretes melatonin. Mammalian pineal does not act as
photoreceptor but it produces the hormone called SPINAL CORD
melatonin which is anti FSH, and anti LH. It inhibits

reproductive function. Melatonin secretions decrease after Fig. – Ventral view of brain

puberty. THINKING PRIMARY MOTOR AREA

Function of fore brain ARM PARETAL LOBE

(1) Olfactory lobe : It is centre of FRONTAL LOBE WERNIKE'S AREA
smell. MEMORY SPEECH
FACE
(2) Cerebrum : Cerebral cortex is made OCCIPITAL
up of grey matter and differentiated into – INTELLIGENCE LOBE

(i) Sensory area

(ii) Motor area BROCA'S AREA VISUAL
(iii) Associated area CORTEX
Sensory and associated area RIGHT HAND NESS

confirm, recognise and evaluate for shape, SMELL TASTE BALANCE
colour, sound, taste and smell for sensory AUDITORY

cells in relation with object. Fig. – Man-different areas in
brain(functional and structural)

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Broca’s area : Known as sensory speech area or motor speech area. Translate thought into speech. Located
into frontal lobe towards left side. It is associated with language area and also interpriate translation of written words
into speech. Damage or injury in Broca’s area (sensory or motor speech area) may result

(i) Aphasia(Inability to speak) (ii) Word deafness, (iii) Word blindness

Cerebrum is a centre for

(i) Intelligence (ii) Emotion (iii) Will power

(iv) Memory (v) Consciousness (vi) Imagination

(vii) Experience (viii) Knowledge (ix) Reasoning
c(xi) It also control A.N.S (autonomic nervous system)
(x) Voluntary controls (xi) Weeping and laughing (xii) Micturition

(xiii) Defecation

If cerebrum is removed animal becomes simple reflax animal.

(3) Diencephalon : It is centre for

(i) Carbohydrate metabolism (ii) Fat metabolism

(iii) It relays impulses from posterior region of brain and also to posterior region of brain.

(iv) Its secretes neurohormone (v) From part of pituitary gland

(vi) Secrete cerebrospinal fluid

Hypothalamus : It is floor of diencephalon and centre for

(i) Hunger (ii) Thirst (iii) Sweating

(iv) Sleep (v) Fatigue (vi) Temperature

(vii) Anger (viii) Pleasure, love and hate (ix) Satisfaction

(x) It is also centre to release factors for endocrine glands.

(xii) Centers for regulation of parasympathetic (cranio-sacral) activity. When stimulated, it causes slowing
down of heart beat, contraction of the visceral muscles.

(4) Mid brain or mesencephalon : It is also completely covered by cerebral hemisphere. It is formed of two parts –

(i) Optic lobes : These are one pair, large sized lobes present on dorsal side. Each is divided transversely into
upper and larger superior coliculus and lower and smaller inferior coliculus. So there are four optic lobes, so called

optic quadrigemina (only in mammals). In frog these are known as TECTUM
bigemina. Valve of vieussens It joins the optic lobe with TEGMENTUM OR CEREBRAL PEDUNCLE

cerebellum.

(a) Superior optic lobe or superior celliculus : They are CRUS OF ITER
concerned with reflex action of eye, head and neck in response to CEREBRUM

visual stimulus. PIGMENTUM

(b) Inferior calliculus : They are concerned with movement Fig. –Lateral view
of head and trunk in response to hearing stimulus.

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(ii) Cerebral peduncle (crura cerebri) : They are the pair of thick bands of longitudinal nerve fiber present

on the floor or ventral side of mid brain. The dorsal part of cerebral peduncle (white matter) is called Tagmentum

while most ventral part (gray matter) is called crura cerebrae or crus of cerebrum. Dorsal thick wall of mid brain is

known as optic tectum. Iter is between tegmentum and tectum. Cerebral peduncle are infect possessing assinding and

desending tracts, connecting upper and lower CORPORA QUADRIGEMINA

region of brain. LATERAL LEMNISCUS
In white matter of cerebral peduncle these

are following sub cortical structure CEREBRAL AQUEDUCT

OCULOMOTOR MESIAL LEMNISCUS

(a) Red nucleus or rustrum nucleus : NUCLEUS SUBSTANTIA NIGRA

TEMPOROPONTINE TRACT

CORTICOSPINAL
(PYRAMIDAL) TRACT
FRONTOPONTINE TRACT
RUBROSPINAL
DECUSSATION OCULOMOTOR NERVE
They are red because rich blood supply andc(a) Pair of anterior optic lobes (which are also known as superior collici) is related with vision.RED NUCLEUS
iron containing pigment or haemoglobin.

(b) Substantia nigra : It is black because
of much deposition of melanin.

(c) Occulomotor nucleus : It is origin point of 3rd cranial nerve (occulomotor) from this region 4th

(Trochlear) nerve also originates.

Reticular activating system : A diffuse network of nerve cell bodies and nerve tracts extends through the
brain stem. It is called reticular activating system (RAS). It screens sensory information so that only certain impulses
reach the cerebrum. For example, when you are alternatively listening to a lecture in the classroom, you are
unaware of rustle of papers from those around you and from the touch of your clothes to the skin. The RAS is also
important in overall activation and arousal. When certain neurons in RAS are active, we are awake, when they are
inhibited by other neurons, we sleep. The pons and medulla have sleep centres that cause sleep when stimulated.
Midbrain has an arousal centre which causes arousal.

Function of Mid brain

(b) Pair of posterior optic lobe (known as inferior collici) related with auditory.

(c) These act as coordination centres between hind and fore brain.

(5) Hind brain : Consists of (i) cerebellum and (ii) medulla oblongata (iii) Pons varolii.

(i) Cerebellum (Sandwitched brain) : Cerebellum is highly convoluted and well developed in mammals. It
controls the most intricate movements of the body. It coordinates sensory information received from muscles/joints,

visual, auditory and equilibrium receptors as well as flow of impulses from cerebral cortex.

Cerebellum is made up of –

(a) Vermis, (b) Cerebellar lobes (= floccular lobes), (c) Lateral lobes, (d) Pons.

The pons is a thick band of transverse nerve fibers. Cerebellum is joined to parts of brain by afferent and
efferent fibres. Mid brain, pons and medulla have several similar functions and they constitute the brain stem.
Peripheral part is formed of grey matter and is called cerebellar cortex while the central part is formed of white
matter and is called cerebellar medulla. The white matter forms a tree-like branching pattern called arbor vitae, so
the cerebellum is solid internally.

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CORPUS
CALLOSUM

FORNIX ANTERIOR CHOROID
PLEXUS
CEREBRUM
THALAMUS

HYPOTHALAMUS THIRD VENTRICLE
PINEAL BODY

MID BRAIN COLLICUS

MAMMILARY CEREBRAL
BODY AQUEDUCT
OF SYLVIUS

cdeccusatn of pyramids. On the dorsal side of medulla there are two nuclei which are called nucleus gracitis (long)OPTICFOURTH
CHIASMA VENTRICLE
CEREBELLUM
HYPOPHYSIS
CEREBRI

(PITUITARY)

PONS

MEDULLA ARBOR VITAE
SPINAL CORD

Fig. – Sagittal section of human brain showing the structures around third
ventricle and parts of midbrain and hindbrain

(ii) Medulla oblongata

Medulla oblongata is the hindest and posterior most part of brain. Cavity is known

as IVth ventricle (metacoel). Which is continuous with central canal of spinal cord. It has v4
a pair of lateral Foramina of Luschka and a median foramen magendic. Cerebrospinal

fluid come in contact by these apertures from internal cavity of the brain to outer fluid of

meninges. A arrangement on its ventral surface there are buldgings of ascending and

descending tract which are called pyramids. On the ventral surface these pyramids cross each other which is called

and nucleus cunaeus. On floor of V4 there is groove called calamus scroptosious.

In the medulla oblongata, most of the sensory and motor fibres cross from one side to the other. Thus, the left

cerebral hemisphere controls the right side of the body and vice versa. The reason for this is not known. The lower

end of medulla passes into the spinal cord. There is no demarcation between the two. However, the medulla is
considered to start at the level of the foramen magnum of the cranium.

(iii) Ponus Varolii : An oval mass, called the pons varolii, lies above the medulla oblongata. It consists mainly
of nerve fibres which interconnect the two cerebellar hemispheres and also join the medulla with highrt brain

centres, hence its name pons means bridge. Pons possess pneumotoxic and apneustic areas or centre. From pons 5,

6, 7 and 8th cranial nerve originate.

Function of hind brain

(1) Cerebellum –

(i) Poorly developed in frog but well developed in mammal.

(ii) It is centre for co-ordination of muscular movement.

(iii) It is primary centre for balancing, equilibrium, orientation.

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(2) Medulla oblongata contain centre for

(i) Heart beats (ii) Respiration (iii) Digestion

(iv) Blood pressure (v) Gut peristalsis (vi) Swallowing of food

(vii) Secretion of gland

(viii) Involuntory function – e.g. vomiting, coughing vasoconstrictor, vasodilater, sneezing, hiccouping.

(ix) It control urination, defecation.

Differences between Cerebrum and Cerebellum

Cerebrum Cerebellum

(1) It is the largest part of the brain, forming four-fifths of its weight. (1) It is the second largest part of the brain, forming one-eighth of its
Cavities or ventricles the brain : The ventricles consist of four hollow
(2) It covers the rest of the brain.fluid filled space inside the brain and same duct for connection between thesemass.
ventricte. (2) It covers the medulla oblongata only.
(3) It is a part of the forebrain. (3) It is a part of the hindbrain.
(i) Olfactory lobe – Rhinocoel (4) It consists of two cerebellar hemispheres and a median vermis.
(4) It consists of 2 cerebral hemispheres each comprising 4 lobes :
frontal, occipital, parietal, temporal.(ii) Cerebrum – I and II ventricle or lateral ventricle or paracoel.(5) It is solid.
(6) White matter form arbor vitae.
(5) It encloses 2 lateral ventricles.c(iii) Foramen of monero : I and II ventricle communicating with IIIrd(7) It maintains posture and equilibrium.

(6) White matter does not form arbor vitae.

(7) It initiates voluntary movements, and is a seat of will,
intelligence, memory etc.

OLFACTORY

CEREBRUM

FORAMEN
OF MONRO

THIRD
VENTRICLE

LATERAL
VENTRICLE

OPTIC
LOBES
ITER

ventricle by foramen of monero. They are two in human and single in rabbit CEREBELLUM

and frog. FOURTH
VENTRICLE
MEDULLA

(iv) Diencephalon : Third ventricle or Diocoel. Fig. Ventricles of brain of rabbit

(v) Iter or cerebral aquiduct or aquiduct of sylvius : It is very METACOEL
narrow cavity between III and IV ventricle.

(vi) Optic lobe : Optocoel.

(vii) Cerebellum : Solid.

(viii) Medulla oblongata : 4th ventricle or metacoel. FORAMEN CEREBRAL FOURTH
OF MONRO AQUEDUCT VENTRICLE
Cavities of brain and spinal cord are modified neurocoel. They
are lined by low columnar ciliated epithelium called ependyma. THIRD
VENTRICLE

Fig. Diagram showing
ventricles of human brain

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Subdivisions, parts and associated strcutures of a vertebrate brain

Divisions Subdivisions Parts Cavity Associated strcutures

(I) Prosencephalon (1) Telencephalon Rhinencephalon I Ventricle (Rhinocoel) Olfactory bulbs
(Forebrain) Olfactory tracts
Olfactory lobes
(II) Mesencephalon Palaeocortex on pallium
(Midbrain)
(III) Rhombencephalon Cerebral hemispheres II or Lateral Ventricles Corpora striata or basal
(Hind brain) (Paracoels) ganglia
Epithalamus (roof) ↓
Thalamus (sides) Corpus callosum
Hypothalamus (floor) Formen of Monro
↓ Neocortex on pallium
Crura cerebri (floor) Paraphysis
Cerebellum III Ventricle (Diacoel) Habenulae
Pineal apparatus
Iter or cerebral aqueduct Parapineal or parietal
(2) Diencephalon cTrapezoidbody
Hypothalamic nuclei
– Optic chiasma
(1) Metencephalon Median eminence
Infundibular stalk
Pituitary
Saccus vasculosus
Mamillary bodies
Anterior choroid plexus

Optic lobes  Tectum
Auditory lobes

Cerebral peduncles

Pons

(2) Myelencephalon Medulla oblongata IV Ventricle (Metacoel) Restiform bodies
Pyramids

Salient or mammalian features of human brain
The salient or mammalian features in the human brain are
(1) Relatively small, solid olfactory lobes.
(2) Very large cerebral hemispheres divided into lobes and with highly folded surface, fully cover the rest of the brain.
(3) Corpus callosum interconnecting the cerebral hemispheres.
(4) Very small pineal body.
(5) A pair of mammillary bodies joined to hypothalamus.
(6) Relatively small, solid optic lobes divided into 4 corpora quadrigemina.
(7) Large, solid cerebellum, with highly folded surface and divided into lobes.

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(8) Pons varolii present anterior to the cerebellum.

Important Tips

• Tela choroidea is the term used for epithalamus and piamater fused.
• Tela choroidea is made up of epithelium and blood vessels.
• Ataxia mean lacks of muscle coordination. Damage to cerebellum is characterized by ataxia.
• Dyslexia involves an inability of an individual to comprehend written language.
• Multiple sclerosis is the destruction of myelin sheath of neurons of CNS.
• An American scientist Roger Sperry got Nobel Prize in 1981 for his outstanding work on split brain theory.
• Parkinson’s disease or Paralysis agitans is a defect of brain.
• Parkinsonism is characterised by tremors and progressive rigidity of limbs caused by a degeneration of brain neurons and a

neurotransmitter called dopamine.
• Avian brain has large sized optic lobes to see the objects on the earth while flying so is called eye brain, while fish brain has large sized

olfactory lobes to smell the prey from a distance so is called nose brain.
• In fishes : Cerebrum is not differentiated in two cerebral hemispheres.
• Hypothalamus has additional lobes to note pressure changes.
• In reptilian brain, pineal eye (parietal body) present in front of pineal body.
• In birds, instictive behaviour is well developed so corpora striata are well developed.
• Grey matter of spinal cord of frog is rectangular white it is butterfly-shaped in mammals.
• Central canal : Cavity of spinal cord.
• Optic bigemina : Two optic lobes in brain and are found from fishes to birds.
• Optic lobes of man are solid and have no optocoel but those of frog have optocoel.
• Optic tectum : Dorsal thick wall of optic lobe.
• Cerebellum is also called little brain.
• Thalami of diencephalon act as relay centres as well as gate keepers of brain.
• Optic chiasma is meant for binocular vision.
• Olfactory lobes of human brain have no rhinocoel while those of frog have rhinocoel.
• Man and birds are less dependent upon smell so olfactory lobes are small sized but are large sized in cartilage fishes (dog fish), dogs and

reptiles as are more dependent upon smell.
• Cerebellum is large sized in fishes, birds and rabbit due to their multidirectional movements and increased dependency on balance.
• Stimulus for hunger : In February 1998, an American scientist Dr. Masashi Yanagisawa reported that a drop of sugar level in blood

stimulates the apettite centres of lateral hypothalamus to release oraxin hormone (Gr. Oraxis = hunger) which stimulates hunger.

c• Nervousdisorders
Agnosia : Failure to recognize;
Alexia : Failure to read;
Agraphia : Failure to write;
Aphasia : Failure to speak (due to injury to Broca’s area)
Analgesia : Loss of sensation of pain;
Anaesthesia : Loss of feeling;
Insomnia : Inability to sleep;
Amnesia : Partial or complete loss of memory;
Coma : Complete loss of consciousness.
Aproxia : Inability to carry out purposeful movements.
Multiple sclerosis : Progressive degenerative disease of CNS and is characterized by many hard scar tissues.
• Caudal equamma : Bundle of roots in last segment of spinal cord.
• Brain stem : Diancephalon + mid brain + pons medulla.
• Cerebro vascular accident (C.V.A) or stroke : Blocking of blood supply of a part of brain.
• Alzeimer : It is the disease appearing usually after 65 year. It is characterized by dementia usually. Usually in this disease is ACH

producing neurons of cerebral cortex and hippocampal lobe are degenerated. It is also seen that a amyloid protein is accumulated in the
brain. It is the matter of research.
• Comissure : The band of neurons connecting similar structure of brain or spinal cord.
• Connective : The band of neurons connecting two different structure of brain and spinal cord.

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• Associate fibres : If joining fiber are joining two similar structure in same halves then, they are called associate fiber.

Spinal cord : Present in spinal canal or vertebral canal of DORSAL DORSAL FUNICULUS OF
vertebral column. It is extended from foramen magnum to FISSURE WHITE MATTER

between I and II lumber vertebra. Spinal cord is swollen in DORSAL SEPTUM DORSAL ROOT

cervical and lumber region which are called cervical and lumber DORSAL HORN OF
enlargement. GREY MATTER

Structure of spinal cord LATERAL
FUNICULUS

Conus medullaris : It is last tapering ends of spinal cord, DURA MATER
its ciliated central canal is called Vth ventricle. PIA MATER

Cauda equine : Nearly upto birth the length of spinal MOTOR
NEURONS

c(2) Dorsal fissure : In the mid dorsal line, there is a groove extending throughout its length.cord corresponds the length of V.C. but after birth there isCENTRAL CANALSUBARACHNOID
vertically no growth of spinal cord but vertebral column grow VENTRAL FISSURE SPACE
upto I lumber vertebra in adult. Spinal nerve come out through
their respective intervertebral foramen, form horse tail hair like BLOOD VESSELS VENTRAL ROOT
VENTRAL HORN OF
VENTRAL GREY MATTER
FUNICULUS

cluster below conus medullaris it is called cauda equine. Fig – T.S. of the spinal cord of mammal
Filum terminales : It is extension of piamater below

conus up to coccyx. In frog spinal cord also extends upto end of vertebral column.

Cisterna terminalis : It is last dilation of subarachnoid space below 1st lumbar vertebra. It is a proper site

for lumber puncture or spinal tap, which is done to drain C.S.F out (5 to 10 ml). This C.S.F is used in diagnosing

many diseases of CNS like meningitis, cyphalis, inter cranial pressure, menningococcal inferaction etc.

Meninges : Like brain, spinal cord is also enclosed with in three membranes. In this case duramater does not

remain attached with the vertebra, instead there is a space between duramater and vertebra called epidural

space. The epidural space is filled with a fluid. The distribution of duramater and piamater in spinal cord is the

same as that of brain.

The cross section of spinal cord reveals the following structures

(1) Central canal : In the centre of spinal cord, there is a canal called central canal. It is filled with

cerebrospinal fluid.

(3) Ventral fissure : It is also a groove situated in the mid ventral line throughout the length of spinal cord.

(4) Dorsal septum : It is a partition extending from dorsal fissure to central canal.

(5) Grey matter : It lies around the central canal in the form of a butterfly.

(6) Dorsal horns : It is like horn of grey matter on the dorsal side.

(7) Ventral horns : On the ventral side of the grey matter are horn like structures the ventral horns.

(8) Lateral horns : These are horns on the lateral side of grey matter.

(9) White matter : White matter is present around grey matter. Spinal cord provides pathway for the

impulses from the brain and to the brain.

Reflex action

First of all Marshal Hall (1833) studied the reflex action. Best and Taylor defined reflex action “simplest form

of irritability associated with the nervous system is reflex actions or a reflex reaction is an immediate involuntary

response to a stimulus.” The reflex actions are involuntary actions because these are not under the conscious

control of the brain. The spinal cord and brain stem are responsible for most of the reflex movements. A few

examples of the reflex actions are withdrawal of hand or leg if pricked by a pin, secretion of saliva as soon as one

thinks of delicious food or mere its sight causes salivation, if the body part is touched with acid or hot object it is

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automatically, without thinking and planning is withdrawn, cycling, motor driving etc. Central nervous system is
responsible for the control of reflex action.

Reflex arc is formed by the neurons forming the pathway taken by the nerve impulses in reflex action. The
simplest reflexes are found in animals involving a single neuron and the following pathway —

Stimulus → Receptor Neuron → Effector → Response

The reflex areas in all the higher animals than coelenterates, include at least two neurons, an afferent or

sensory neuron carrying impulses from a receptor towards aggregation of nervous tissue which may be a ganglion,

nerve cord or central nervous system and an efferent or motor neuron carrying impulses away from the aggregation

to an effector.

(a) Component of reflex action : The whole of the reflex are includes six parts –
(1) Receptor organs : Receptors are windows of the body or guards of the body. These are situated on all,
important organs, for example – eyes, nose, ear, tongue, integument etc. These perceive the stimuli from out side the body.NERVE IMPULSE FROM
PAIN RECEPTOR
c(2) Sensory neurons : These are also termed afferent neurons. These carry the stimuli from receptors to
PAIN CELL BODY RELAY
RECEPTOR NEURONE

NEEDLE SPINAL DORSAL
PRICK NERVE ROOT

RECEPTOR, e.g.,
FREE NERVE
ENDING

MOTOR SPINAL CORD IN
NEURON TRANSVERSE
SECTION
WHITE MATTER SYNAPSE GRAY MATTER

EFFECTOR, e.g., MUSCLE FIBRES Fig. Reflex arc

spinal cord. These neurons are situated in the ganglion on the dorsal side of spinal cord.

(3) Nerve centre : Spinal cord is termed as nerve centre. Synaptic connections are formed in it.

(4) Association neurons : These are also called intermediate neurons or interstitial neurons. These are
found in spinal cord. They transfer the impulses from sensory neurons to motor neurons.

(5) Motor neurons : These are situated in the ventral horn of spinal cord. These carry the impulses to
effector organs.

(6) Effector organs : These are the organs, which react and behave in response to various stimuli, for
example – muscles and glands.

(b) Mechanism of reflex action : The time taken by a reflex action is too short, for example – in frog it is
0.3 meter per second and in man 5-120 meter per second. Whenever, a part of the body is stimulated by any
stimulus, for example – pin pricking, then the stimulus is converted into impulse. This impulse is perceived by the
dendrites of sensory neurons. From here, the stimulus reaches the spinal cord through axonic fibres. In the spinal
cord, this stimulus passes through synaptic junctions and reaches the intermediate neurons, from where this stimulus
reaches the effector organs through visceral motor nerve fibres. As soon as the stimulus reaches the effector organs,

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