Exam #4: Perineum I

Question 1

Where is the perineum located?

Answer 1

Inferior to the pelvis/ pelvic diaphragm

Question 2

What forms the boundary of the diamond-shaped perineal area?

Answer 2

1) Coccyx
2) Ischial Tuberosities
3) Pubic Symphysis

Question 3

What are the two triangles that the perineum is divided into? How are these two triangles divided?

Answer 3

• Anal Triangle & Urogenital Triangle

- Divided by a “line” from IT–>IT

Question 4

What are the general contents of the anal triangle?

Answer 4

• Anal canal

- Ischioanal fossae

Question 5

What are the general contents of the urogenital triangle?

Answer 5

Male= penis, scrotum, testis, & epididymis 
Female= vulva, mons pubis, labia majora, labia minora, vestible, vaginal orifice, clitoris

Question 6

What is the anal canal & what are the borders of the anal canal?

Answer 6

Anal canal= terminal portion of large intestine

Borders= pelvic diaphragm–>anus

Question 7

What divides the anal canal into upper & lower halves?

Answer 7

Pectinate line

Question 8

What forms the pectinate line?

Answer 8

Anal valves/ semilunar folds on the inferior aspect of the anal columns

Question 9

What is the difference between the embryological derivation of the upper & lower half of the anal canal?

Answer 9

Upper 1/2= Hindgut endoderm

Lower 1/2= Ectoderm of proctodeum

Question 10

What is the difference between the epithelium of the upper & lower halves of the anal canal?

Answer 10

Upper 1/2= Simple columnar epithelium (like intestine)

Lower 1/2= Stratified squamous epithelium (like skin)

Question 11

Do both halves of the anal canal contain anal columns?

Answer 11

No, only the upper half

Question 12

Describe the innervation of the upper & lower halves of the anal canal.

Answer 12

Upper= autonomic (pressure & stretch only) 
Lower= somatic (pain)

Question 13

What arteries supply the upper & lower halves of the anal canal?

Answer 13

Upper= Superior & middle rectal arteries 
Lower= Inferior rectal artery

Question 14

What veins drain the upper & lower halves of the anal canal? Clinically, that is the important distinction between these two veins?

Answer 14

Upper= Superior rectal vein
Lower= Inferior rectal vein

• Superior rectal vein drains into the portal system but the Inferior rectal vein does NOT

Question 15

What is the function of the transverse folds of the rectum?

Answer 15

Break-up the column of stool–>decreases distal pressure (& urge to defecate)

Question 16

What are the differences between the internal & external anal sphincters? How is this functionally important?

Answer 16

Internal=

• Smooth muscle (thickening of inner circular muscle layer)
• Involuntary

External=

• Skeletal muscle
• Voluntary & innervated by inferior rectal nerve

*The inner sphincter involuntarily relaxes as stool comes down; you control the external sphincter

Question 17

What is the ischiorectal fossa?

Answer 17

Fat-filled space lateral to the anal canal

Question 18

What are the superior & lateral boundaries of the ischiorectal fossa?

Answer 18

Lateral= obturator internus m. 
Superior= Levator ani m. (pelvic diaphragm

Question 19

What is the Pudendal Canal? What are the contents of the pudendal canal?

Answer 19

Below the tendinous arch, the obturator fascia splits into the pudenal canal, which contains:

1) Pudendal a.
2) Pudendal v.
3) Pudendal n. (S2-S4)

Question 20

Describe the path of the pudendal nerve into the perineum.

Answer 20

• Exits pelvis via the greater sciatic foramen
• Enters perineum via lesser sciatic foramen
• Branches into inferior rectal, & branches to penis or labia/ clitoris

Question 21

What forms the greater & lesser sciatic foramen?

Answer 21

Sacrospinous ligament= Greater

Sacrotuberus ligament= Lesser

Question 22

What are the superior & inferior rectal arteries branches of?

Answer 22

Superior rectal= IMA

Inferior rectal= Internal Iliac–>Internal Pudendal

Question 23

What are hemorrhoids? How does the etiology differ between internal & external hemorrhoids?

Answer 23

Dilated & enlarged veins

• Internal= superior rectal vein that drains into portal system
• External= inferior rectal vein that drains into internal iliac
• **Internal hemorrhoids are typically caused by issues w/ the portal system

Question 24

What are the fascial layers of the urogenital triangle?

Answer 24

Superficial fascia

• Camper’s Fascia
• Colles Fascia (was Scarpa’s Fascia in abdomen)

Deep fascia (continuous w/ fascia of the external oblique & rectus sheath in abdomen)

Question 25

How does Camper’s Fascia differ between males & females in the urogenital triangle?

Answer 25

Males= Diminished amount of fat 
Females= makes up substance of fat in mons pubis & labia majora