The Perineum and External Genitalia

Question 1

An imaginary line drawn between the ischial tuberosities divides the pelvic outlet into an anterior __1__ and a posterior __2__

Answer 1

1) urogenital triangle

2) anal triangle

Question 2

What structures are contained in the anal triangle?

Answer 2

Anal canal, with the ischioanal fossa and its contents on either side

Question 3

Where does the rectum become the anal canal?

Answer 3

At the u-shaped sling created by puborectalis

Question 4

How does the arterial supply change in the anal canal?

Answer 4

Upper two-thirds: From inferior mesenteric artery

Lower third: from internal iliac atery

Question 5

How does the venous drainage change in the anal canal?

Answer 5

Upper two-thirds: to portal venous system

Lower third: to caval venous system

Question 6

How does the lymphatic drainage change in the anal canal?

Answer 6

Upper two-thirds: to internal iliac lymph nodes

Lower third: to superficial inguinal lymph nodes

Question 7

How does the nerve supply change in the anal canal?

Answer 7

Upper two-thirds: Visceral motor (mixed sympathetic and parasympathetic) and sensory information

Lower third: Somatic motor and sensory innervation

Question 8

What boundary is marked by the pectinate line?

Answer 8

The approximate boundary between the embryologically different region of the anal canal

Question 9

What is the nerve supply to the internal anal sphincter?

Answer 9

Autonomic

Question 10

What is the nerve supply to the external anal sphincter?

Answer 10

Somatic

Question 11

What are the different parts of the external anal sphincter called?

Answer 11

Subcutaneous, superficial and deep parts

Question 12

Which part of the external anal sphincter is related posteriorly to the fibres of puborectalis?

Answer 12

Deep part

Question 13

The ischioanal fossa are largely filled with __1__ and are a common site for infection, resulting in abscesses which may rupture to produce a fistula. A fistula in this region might open between the ischioanal fossa and __2__

Answer 13

1) fat

2) anal canal

Question 14

The pudendal nerve and internal pudendal vessels travel in the __1__, in the __2__ wall of each ischioanal fossa

Answer 14

1) pudendal canal

2) lateral

Question 15

What branches leave the pudendal neurovascular bundle as it traverses the ischioanal fossa?

Answer 15

Inferior rectal artery, vein and nerve

Question 16

Why would you carry out a pudendal nerve block?

Answer 16

To anaesthetise the perineum during episiotomy

Question 17

The urogenital triangle is subdivided into deep and superficial parts by the __?__

Answer 17

Urogenital diaphragm - a triangular layer of muscle and dense fascia (perineal membrane) that extends between the inferior ischiopubic rami and merges with the perineal body posteriorly

Question 18

The urogenital triangle is pierced by the __1__ in both sexes and by the __2__ in females. In both sexes, muscles within the urogenital diaphragm form the __3__

Answer 18

1) urethra
2) vagina
3) external urethral sphincter

Question 19

What is the nerve supply to the external urethral sphincter?

Answer 19

Deep branch of perineal nerve

Question 20

From which vessel does the external pudendal artery branch? What does it supply?

Answer 20

Femoral artery; skin of scrotum and labia

Question 21

What is contained within the superficial perineal pouch? What is the name of the membranous layer of superficial fascia?

Answer 21

Contains testes, vas deferens and root of penis

Colle’s fascia

Question 22

Which structures do the bulb of the penis and the crura of the corpora cavernosa attach to?

Answer 22

Perineal membrane and ischiopubic ramus

Question 23

what are the actions of bulbospongiosus and ischiocavernosus? What is their nerve supply?

Answer 23

Contraction of these muscles prevents venous return, thereby allowing engorgement of the erectile tissues.

Deep branch of perineal nerve

Question 24

Which arteries supply the penis?

Answer 24

Internal pudendal:

artery of bulb, deep artery of penis, dorsal artery of penis

Question 25

What is the sensory nerve supply to the skin of the scrotum?

Answer 25

Anterior: Ilioinguinal, genital branch of genitofemoral

Posterior: Pudendal, posterior scrotal

Question 26

From what is the tunica vaginalis derived?

Answer 26

Processus vaginalis

During descent of the testes the testis pushes through a serous pouch of the peritoneum

Question 27

Wy are UTIs more common in females than males?

Answer 27

Shorter urethra

Question 28

Deep to the skin and fat of each __1__ lies a mass of erectile tissue called the bulb of the __2__, which is firmly attached to the underlying __3__.

Answer 28

1) labia majora
2) vestibule
3) perineal membrane

Question 29

The bulbs of the vestibule partially overlie the __1__ glands and are, themselves, covered with thin sheets of muscle: the __2__ muscles

Answer 29

1) greater vestibular

2) bulbospongiosus

Question 30

The bulbs of the vestibule join together anteriorly to form the __?__

Answer 30

glans of the clitoris

Question 31

Which tissues contribute to the formation of the clitoris?

Answer 31

Bulb of vestibule and corpora cavernosa

Question 32

How is the clitoris anchored in the perineum?

Answer 32

Via crura which insert onto ischiopubic ramus

Question 33

What is the function of of the vestibular glands (Bartholin’s glands)?

Answer 33

Secretion of mucus into vagina during sexual arousal

Question 34

To which nodes does lymph from perineal structures drain?

Answer 34

Superficial inguinal lymph nodes, the deep and then internal iliac