perineum

Question 1

name the structures that line the pelvic outlet

Answer 1

• pubic symphysis
• ischiopubic ramus
• ischial tuberosity
• ST ligament
• coccyx

Question 2

what are the two triangles within the pelvic outlet

Answer 2

• urogenital triangle

- anal triangle

Question 3

describe the function and location of the perineal body

Answer 3

anchor point for many muscles, it is composed of fibrous connective tissue
found between the urogenital and anal triangle

Question 4

describe the levator ani and its divisions

Answer 4

the pelvic floor muscle (funnel shape)

3 main divisions:

      - ischiococcygeus
      - iliococcygeus
      - pubococcygeus

Question 5

what is the nerve supply to the levator ani

Answer 5

pudendal nerve (S2-4)
nerve to levator ani (S3-4)

Question 6

define puborectalis and how its function can be lost

Answer 6

sling of fiber that come anteriorly to swing around the rectum, creating the anorectal angle (under tonic contraction)
if damage occurs to pudendal or levator ani nerve then loss of function can occur, no control of bowel function

Question 7

what is the arterial supply and lymphatic drainage to the anal canal

Answer 7

superior rectal artery –> middle rectal –> inferior rectal

pre-aortic –> internal iliac –> superficial inguinal nodes

Question 8

what is the rectal/anal venous drainage and what is its clinical significance

Answer 8

superior rectal vein anastomosis with inferior rectal vein

portal hypertension can cause ano-rectal varices
hemorrhoids also often occur here

Question 9

describe the landmarks of the ischioanal fossa

Answer 9

laterally = ischial tuberosity

posteriorly = coccyx

midline = perineal body

(avoid lateral apex = pudendal vessels)

Question 10

why is there more muscle in the deep perineal pouch of a female compared to a male

Answer 10

short vertical course of the urethra, therefore additional muscles to help control flow of urine

Question 11

what artery supplies the perineum

Answer 11

internal pudendal artery

Question 12

what are the main branches of the internal pudendal artery

Answer 12

• inferior rectal
• perineal
• dorsal artery of penis/clitoris

(same for nerves of pudendal)

Question 13

what is the main nerve supply to the perineum

Answer 13

pudendal nerve S2-4

Question 14

what occurs for defaecation to be carried out?

Answer 14

• relaxation of puborectalis
• relaxation of internal and external sphincters
• parasympathetic contraction of pelvic muscles
• increased intra-abdominal pressure