Anatomy - 1

Division between false and true
pelvis

pelvic brim (or inlet)

Boundaries (roof and floor) of the
true pelvis

pelvic inlet (brim) + pelvic outlet

Borders of the pelvic brim (inlet)

sacral promontory>sacroiliac
joint> sacral alae> iliopectineal
line> pubic rami>pubic symphysis

Diameters of the pelvis

Transverse / oblique /
anteriorposterior

Anatomical anteroposterior
conjugate of the pelvis

AP diameter - sacral promontory
to pubic symphysis

Diameter of the anatomical
conjugate of the pelvis

11cm

Obstetric conjugate of the pelvis

smallest AP diameter = sacral
promontory to pubic symphysis

Diagonal conjugate of the pelvis

AP diameter measure from
bottom of pubic symphysis to
sacral promontory - used to
measure obstetric conjugate

(minus 1.5-2cm)

Normal obstetric transverse
diameter length

13cm

Oblique diameter of pelvis

12cm (Sacroiliac joint to
iliopectineal line)





Where does the pudendal nerve
arise from?

Ventral rami S2 S3 S4

What are the branches of the
pudendal nerve?

inferior rectal nerve
perineal nerves

dorsal nerve of penis/clitoris

Action of pudendal nerve

Sensation of labia clitoris penis
scrotum anal canal

Afferent sensation for erection

Motor function of external anal
and urethral sphincters

Course of the pudendal nerve

ventral rami S2 S3 S4 > lesser sciatic
foramen > greater sciatic foramen >
joins internal pudenal artery and vein
in pudendal canal and branches to
form inferior rectal nerve, perineal
nerve and dorsal nerve of penis/clitoris

Where does the perineal nerve arise
from?

Pudendal nerve (ventral rami S2 3 4)

What are the branches of the
perineal nerve?

superficial and deep

What does the perineal nerve
supply?

superficial - supplies the posterior
scrotal/labial nerves

deep perineal - supplies muscles -
superficial transverse perineal muscle,

bulbospongiosus, ischiocavernosus,
and corpus cavernosus and Sphincter

urethræ.

What does the inferior rectal
nerve supply?

motor supply - external anal
sphincter

sensation - anal canal to pectinate
line

Where does the inferior rectal
nerve arise from?

ventral rami S 2 3 4 > pudendal
nerve > inferior rectal nerve

Where does the ilioinguinal nerve
arise from?

from L1 anterior ramus

What does the ilioinguinal nerve
innervate?

sensation for medial thigh
anterior labia and clitoris
anterior scrotum and root of the

penis

What route does the ilioinguinal
nerve take?

L1 - iliohypogatric> ilioinguinal >
inguinal canal

Innervation of the anal sphincter