Lecture 16: Perineum

Question 1

Urogenital and Anal triangles

Answer 1

Made from muscles of the perineum

Anal: more posterior
Urogenital: more anterior

Question 2

What makes up the Pelvic Outlet?

Answer 2

• Pubic Symphysis
• Ischiopubic Ramus
• Ischial Tuberosity
• ST lig.
• Coccyx

*Roughly diamond shape

Question 3

What is the Perineal Body?

Answer 3

Made of fibrous CT, an attachment point!

Attaching is?

• Levator ani
• Bulbospongiosus
• External anal sphincter
• Perineal Muscles

Question 4

What two main muscles make up the pelvic floor?

Answer 4

1. Levator ani
2. Coccygeus

Question 5

Levator Ani divisions and supply

Answer 5

1. Iliococcygeus
2. Pubococcygeus

Forms a V shaped structure

Pudendal nerve (S2-4) and nerve to levator ani (S3-4)

Question 6

Levator Ani: Pubococcygeus

Answer 6

1. Levator Prostatae/pubovaginalis
2. Pubococcygeus
3. Puborectalis; helps maintain fecal continence, forms sling around the rectum (creates angulation)

Question 7

Levator divisions: Iliococcygeus

Answer 7

Attaches to fascia of Obturator internus, prevents prolapse of pelvic viscera

Question 8

Label Levator Ani muscles

Answer 8

Question 9

What is the External Anal sphincter? Function and innervation?

Answer 9

Made of skeletal muscle, it closes the anus (accompanied by puborectalis) and is also under partial voluntary control!

From perineal body to anococcygeal ligament

supplied by Pudendal Nerve (S2-4) - inferior rectal branch

Question 10

Internal Anal sphincter

Answer 10

Smooth Muscle (involuntary control (ANS))

Deep to External Anal Sphincter (seperated by CT)

Question 11

Label

Answer 11

Question 12

Landmarks of the urogenital and anal Sphincters

Answer 12

Laterally: ischial Tuberosity

Posteriorally: Coccyx

Midline: Perineal Body

**avoid the lateral apex (where the nerves are) → impotence or incontinence

Question 13

The Anal Canal

Answer 13

Where the rectum pierces the pelvic floor it becomes the Anal canal (once passed the puborectalis)

Question 14

Arterial and Lymphatics of the rectum

Answer 14

• *Superior rectal artery (inf mesenteric)**
• Pre-aortic nodes @ L3*
• *Middle rectal artery (int iliac)**
• Internal iliac nodes*
• *Inferior rectal artery (int pudendal)**
• Internal Iliac nodes*

** anal canal inferior to pectinate line (SF inguinal nodes)

Question 15

Rectal/anal venous drainage

Answer 15

Superior and inferior recal vein meet at portal-systemic anastomosis

These drain the internal and external venous plexuses

Question 16

The perineal membrane

Answer 16

Has an anterior deficiency (where the deep dorsal vein of penis/clitoris moves through)

• Attachment site for nearly all perineal muscles eg; deep transverse perineal muscles and compressor urethra
• Forms inferior layer of urogenital diaphragm/ Deep perineal pouch

Question 17

Urogenital Diaphragm

Answer 17

Question 18

What’s the male/female variation of the Deep Perineal Pouch

Answer 18

Female:

• Compressor urethrae
• DOrsal n. of the clitoris
• **Bartholins glands in SF pouch

Male:

• ‘membranous’ urethra
• Bulbospongiosus
• DOrsal n. of the penis

Question 19

Superficial Perineal Pouch

Answer 19

Structures between the perineal membrane and skin

• Nerves + vessels
• Erectile tissues
• Perineal muscles
• Bartholins gands (females)

Question 20

Internal Pudendal artery important branches. Draw.

Answer 20

Question 21

Pudendal Nerve

Answer 21

Mirrors the artery. (S2-4) motor and sensory

Perineal muscles, ext. urethral sphincter, skin of genitalia, erectile muscles

Question 22

Sex- the nervous system

Answer 22

Question 23

Saddle anasthesia

Answer 23

Compression of cauda equina (S5 to anus) → numb butt thighs and perineum