Perineum

Question 1

Ischio-anal fossa

Answer 1

Lateral wall - ischium, obturator internus and sacrotuberous ligament
Medial wall - levator ani

Question 2

Superficial perineal pouch

Answer 2

Between perineal membrane and membranous layer of superficial fascia

Question 3

Structures in superficial perineal pouch

Answer 3

Erectile structures (penis, clitoris)
Skeletal muscles associated with parts of the erectile structures

Question 4

Erectile tissues

Answer 4

Two sets of erectile structures
1. Pair of corpus cavernosum at anterior side side of urogenital triangle
2. Surrounds opening of urogenital system
In women - bulbs of vestibule + greater vestibular gland
In men - corpus spongiosum (bulbo-urethral gland is in deep perineal pouch)

Question 5

Erection

Answer 5

Parasympathetic fibers by S2-S4 carried by inferior hypogastric plexus

Question 6

Artery supplying penis and clitoris

Answer 6

Internal pudendal artery

Question 7

Muscles in superficial perineal pouch

Answer 7

3 pairs of muscles - all supplied by pudendal nerve

Ischiocavernosus, bulbospongiosus and superficial transverse perineal muscle

Question 8

Colles fascia

Answer 8

Superficial fascia of urogenital triangle attached posteriorly to perineal membrane (thus does not extend into anal triangle) and to ischiopubic rami and therefore does not extend into the thigh
Defines external limit of superficial perineal pouch
Fluids that accumulate in superficial perineal pouch will not track into anal triangle or thigh

Question 9

Urethral rupture

Answer 9

Commonest - rupture of proximal spongy urethra below perinal membrane - urine goes into superficial perineal pouch and descends into scrotum and onto anterior abdominal wall deep to the superficial fascia

If severe pelvic fracture, may occur at prostatomembranous junction above deep perineal pouch, urine will enter true pelvis

Worst urethral rupture is serious pelvic injuries when there is complete disruption of the puboprostatic ligaments - prostate dislocated superiorly.

Question 10

Pudendal nerve

Answer 10

S2-S4
Leaves pelvic cavity through greater sciatic foramen beneath piriformis, passes around sacrospinous and enters anal triangle by passing medially through lesser sciatic foramen. Travels along lateral wall of ischio-anal fossa in the pudendal canal (formed in fascia that covers obturator internus). Pudendal canal also contains internal pudendal vessels.

Question 11

Branches of pudendal nerve

Answer 11

Inferior rectal nerves
Perineal nerves
Dorsal nerve of penis/clitoris

Question 12

Inferior rectal of pudendal nerve

Answer 12

External anal sphincter + general sensory to skin of anal triangle

Question 13

Perineal nerve of pudendal nerve

Answer 13

skeletal muscles in superficial and deep perineal pouches.

Largest sensory branch is posterior scrotal nerve in mean and posterior labial nerve in women

Question 14

Dorsal nerve of clitoris/penis of pudendal nerve

Answer 14

Enters deep perineal pouch and passes along lateral margin and exits by passing inferiorly through perineal membrane just inferior to pubic symphysis where it meets body of clitoris/penis. Sensory to penis and clitoris

Question 15

Other somatic nerves in perineum

Answer 15

Other than pudendal nerve,

branches of ilioinguinal, genitofemoral, posterior femoral cutaneous and anococcygeal nerves

Question 16

Visceral nerves in perineum

Answer 16

Sympathetics to skin

Inferior hypogastric plexus - parasympathetic to erectile tissues

Question 17

Internal pudendal artery

Answer 17

Most significant artery in perineum. Other arteries include external pudendal, testicular and cremasteric

Question 18

Internal pudendal artery

Answer 18

Passes around ischial spine, where artery lies lateral to nerve and enters perineum through lesser sciatic foramen in pudendal canal

Question 19

Branches of internal pudendal artery

Answer 19

similar to pudendal nerve
Inferior rectal artery
Perineal artery
branches to erectile tissues of penis/clitoris

Question 20

Branches to erectile tissues of penis/clitoris

Answer 20

Men - artery of bulb of penis, urethral, deep artery of penis, dorsal artery of penis
Women - arteries of bulb of vestibule, deep artery of clitoris, dorsal artery of clitoris

Question 21

External pudendal artery

Answer 21

Consist of superficial and deep vessel, originate in femoral artery of thigh, supply skin of penis and scrotum/clitoris and labia majora

Question 22

Cremasteric artery

Answer 22

Men - Originate from inferior epigastric branch of external iliac artery, accompany spermatic cord into scrotum.
Women - follow round ligament of uterus through inguinal canal

Question 23

Internal pudendal veins

Answer 23

Veins in perineum go here and drain into internal iliac veins in pelvis, except deep dorsal vein of penis/clitoris which drain into plexus of veins surrounding prostate in men/bladder in women

Question 24

External pudendal veins

Answer 24

Drain anterior parts of labia majora/scrotum, connect with femoral vein in thigh. Superficial dorsal veins of penis/clitoris are tributaries of external pudendal veins.

Question 25

Lymphatics in perineum

Answer 25

Deep parts of perineum - internal iliac nodes in pelvis
Superficial tissue of penis/clitoris + scrotum/labia majora - mainly into superficial inguinal nodes
Glans penis/clitoris, labia minora and terminal inferior end of vagina - deep inguinal and external iliac nodes