1. INTRODUCTION TO THE HUMAN BODY

Cavities of the body

 Body organs are contained and
protected within four cavities:

1. Cranial
2. Thoracic
3. Abdominal
4. pelvic

CRANIAL CAVITY

 Contains the brain.
 Boundaries are formed by the bones of the skull.
1. Anteriorly – 1 frontal bone
2. Laterally - 2 temporal bones
3. Posteriorly – 1 occipital bone
4. Superiorly – 2 parietal bones
5. Inferiorly – 1 sphenoid and 1 ethmoid bone



THORACIC CAVITY

 Situated in the upper part of the trunk
 Boundaries are formed by the thoracic cage and supporting

muscle.
1. Anteriorly – the sternum and costal cartilages of the ribs
2. Laterally - 12 pairs of ribs and the intercostal muscles
3. Posteriorly – the thoracic vertebrae
4. Superiorly – the structures forming the root of the neck
5. Inferiorly – the diaphragm, a dome-shaped muscle.





CONTENTS

 The main organs and structures include:
1. The trachea, 2 bronchi, 2 lungs
2. The heart, aorta, superior and inferior vena cavae,

numerous other blood vessels.
3. The oesophagus
4. Lymph vessels and lymph nodes
5. Some important nerves.
 The mediastinum is the space between the lungs, heart,

oesophagus and blood vessels.

ABDOMINAL CAVITY

 Largest body cavity and its oval in shape.

Occupies most of the trunk and its boundaries are:

1. Superiorly – the diaphragm, which separate it from the
thoracic cavity

2. Anteriorly – the muscles forming the anterior abdominal
wall

3. Posteriorly – the lumbar vertebrae and muscles forming
the posterior abdominal wall.

4. Laterally – the lower ribs and parts of the muscles of the
abdominal wall

5. Inferiorly – continuous with the pelvic cavity

Abdominal cavity is divided into the nine
regions.

Contents

 Occupied by the organs and glands of the digestive
system.

1. The stomach, small intestine and most of the large
intestine

2. The liver, gall bladder, bile ducts and pancreas.
 Other structures include:
1. The spleen
2. 2 kidneys and the upper part of the ureters
3. 2 adrenal (suprarenal) glands
4. Numerous blood vessels, lymph vessels and nerves.
5. Lymph nodes.



Pelvic cavity

 Roughly funnelshaped and extends from the lower end
of the abdominal cavity.

 Boundaries are:
1. Superiorly – continuous with the abdominal cavity
2. Anteriorly - the pubic bones
3. Posteriorly – the sacrum and the coccyx
4. Laterally – the innominate bones
5. Inferiorly – the muscles of the pelvic floor.





Contents

 Sigmoid colon, rectum and anus
 Some loops of the small intestine
 Urinary bladder, lower parts of the ureters and the

urethra
 In the female:
1. Uterus
2. Uterine tubes
3. Ovaries
4. vagina

 In the male :
1. Prostate gland
2. Seminal vesicles
3. Spermatic cords
4. Deferent ducts
5. Ejaculatory ducts
6. urethra