2. Pelvic and Perineal Myology

Question 1

What is the perineal body?

Answer 1

• Fibromuscular mass in the midline between the anal canal and the perineal membrane that contains collagen and elastic fibers.
• It is a attachment point for the [Bulbospongiosus M, External Anal Sphincter M., Superficial Transverse Perineal M. and Deep Transverse Perineal M.

Question 2

_______sometimes classified as a central tendon of the Pelvic and Urogenital Diaphragms

Answer 2

Perineal body

Question 3

What are the superficial perineal muscles (3)?

Answer 3

• 1. Superficial Transverse Perineal M.
• 2. Ischiocavernosus M.
• 3. Bulbospongiosus M.

They are superficial to the perineal membrane.

Question 4

Superficial Transverse Perineal M.

Axn:

N:

Answer 4

A:

• Support and fix Perineal Body
• Supports abdominopelvic viscera and
• Resists increases in Intraabdominal Pressure

N: Deep Perineal N.

Question 5

Ischiocavernosus M.

Axn:

N:

Answer 5

A:

• Maintain erection of penis or clit by compressing venous drainage, forcing blood from the Crura into the body of the penis or clit

N: Deep Perineal N.

Question 6

Bulbospongiosus M.

Axn:

N:

Answer 6

A: Support and fix Perineal Body (B);

• Males: compress Bulb of Penis, assist erection by compressing venous drainage, forcing blood from the Root of the Penis to the Body of the Penis, expels final drops of Urine/ Semen from the Urethra (♂)
• Females: compress Vaginal orifice, assist in erection of Bulbs of Vestibule of Vagina and compresses the Greater VestibularGland(♀)

N: Deep Perineal N.

Question 7

What is the urogenital diaphragm?

*likely will not see in lab*

Answer 7

Deep and separated from the superficial perineal m. by the perineal membrane, but has parts to the superfial perineal muscles and perineal membrane.

Question 8

What muscles make up the urogenital diaphragm?

Answer 8

1. External Urethral Sphincter M. (Sphincter Urethrae M.).

• In females; it will have two parts: Compressor Urethrae M. and the Urethrovaginal Sphincter M.
• In males; it will have another component: Compressor Urethrae M.

2. Deep Transverse Perineal M: in males it is skeletal muscle and in F it is smooth muscle.

Question 9

External Urethral Sphincter M. (Sphincter Urethrae M.)

A:

N:

Answer 9

• Axn: Constrict urethra to maintaining urinary continence
• N: Dorsal Nerve of the Penis (♂) or Clitoris (♀)

Question 10

Compressor Urethrae M.

Axn:

N:

Answer 10

Extends laterally from the external urethral sphincter

• A: Constrict Urethra maintaining urinary continence
• N: Dorsal Nerve of the Penis (♂) or Clitoris (♀)

Question 11

Urethrovaginal Sphincter M

AXN:

N:

Answer 11

(a slip of the external urethral sphincter m. that also surrounds the vagina).

• A: Compress vagina
• N: Dorsal Nerve of the Clitoris

Question 12

Deep Transverse Perineal M.

(in Males, bc in F it is smooth muscle)

Axn:

N:

Answer 12

A:

• Support and fix perineal body,
• supports abdominopelvic viscera
• resists increases in intraabdominal pressure

N: Deep Perineal N.

Question 13

What are the anal muscles?

Answer 13

• 1. External Anal Sphincter M. (skeletal muscle; voluntary)
• 2. Internal Anal Sphincter M. (smooth muscle; involuntary)

Question 14

External Anal Sphincter M.

A:

N:

Answer 14

A:

• Constricts the Anal Canal during Peristalsis
• resists Defecation
• supports and fix Perineal Body

N: Inferior Rectal N.

Question 15

Internal Anal Sphincter M. is an involuntary sphincter that surrounds ______________ and is innervated by what?

Answer 15

• Surrounds: superior 2/3 of Anal Canal
• I: Pelvic Splanchnic nerves

Question 16

Describe the organization of the pelvic diaphragm:

Answer 16

It is made up of four muscles:

• The three Levator Ani Ms
  
  • ​From medial -> lateral:
    
    • Puborectalis M.,
    • Pubococcygeus M.
    • Iliococcygeus M.
• Coccygeus M.

Question 17

Puborectalis M.

Axn:

N:

Answer 17

A:

• Maintain Anorectal Flexure
• Supports Pelvic Viscera
• Resists increases in Intraabdominal Pressure

N:

• Nerve to the Levator Ani M. (S4),
• Inferior Rectal N.
• Branches of the Coccygeal Plexus

Question 18

Pubococcygeus M.

Axn:

N:

Answer 18

A:

• Supports Pelvic Viscera
• Resists increases in intraabdominal pressure

N:

• Nerve to the Levator Ani M. (S4),
• Inferior Rectal N.,
• branches of the Coccygeal Plexus

Question 19

**** will not see in lab***

What is special about the pubococcygeus M.?

Answer 19

Makes accessory muscles that go to nearby structures that all have the same axn and innervation.

1. Levator Prostatae M. (in males)
2. Pubovaginalis M. (in females)
3. Puboperinealis M (both)
4. Puboanalis M. (both)

Question 20

Iliococcygeus M.

Axn:

N:

Answer 20

A:

• Supports Pelvic Viscera,
• Resists increases in intraabdominal pressure

N:

• Nerve to the Levator Ani M. (S4)
• Inferior Rectal N.
• Branches of the Coccygeal Plexus

Question 21

Coccygeus M.

Axn:

N:

Answer 21

A:

• Support Pelvic Viscera
• Flexes Coccyx

N:

• Nerve to the Coccygeus (S4,5; branches of the Coccygeal Plexus)

Question 22

What are the lateral pelvic wall muscles?

Answer 22

• 1. Obturator internus M.
• 2. Piriformis M.

Question 23

Obturator Internus M.

Axn:

N:

Answer 23

A:

• Rotate Thigh laterally
• Stabilize the Femoral Head in the Acetabulum

N: Nerve to the Obturator Internus M.

Question 24

Piriformis M.

Axn:

N:

Answer 24

A:

• Rotate thigh laterally
• abduct thigh
• stabilize femoral head in acetabulum

N: Nerve to the Piriformis M.