Pelvic and Perineal Myology Lecture (Dr. Olinger)

Question 1

Helpful Note: The Perineal Body

Answer 1

• The Perineal Body is an irregular fibromuscular mass in the midline between the Anal Canal and the Perineal Membrane, it contains COLLAGENOUS and ELASTIC Fibers and is the attachment point for the BULBOSPONGIOSUS M, EXTERNAL ANAL SPHINCTER M., SUPERFICIAL TRANSVERSE PERINEAL M. and DEEP TRANSVERSE PERINEAL M.
• It is sometimes classified as a central tendon of the Pelvic and Urogenital Diaphragms.

Question 2

Superficial Perineal Muscles (superficial most muscles of the Perineum)

Answer 2

1. SUPERFICIAL TRANSVERSE PERINEAL M.
   - O: Ischiopubic Ramus and Ischial Tuberosity

• I: Perineal Body
• A: Support and fix Perineal Body, supports Abdominopelvic Viscera and resists increases in Intraabdominal Pressure
• N: Deep Perineal N

2. ISCHIOCAVERNOSUS M.
   - O: Ischiopubic Ramus and Ischial Tuberosity

• I: Medial aspect of the Crus of the Penis (♂) or Clitoris (♀) and
  Perineal Membrane medial to the Crura (B)
• A: Maintain erection of Penis or Clitoris by compressing venous
  drainage, forcing blood from the Crura into the body of the Penis or Clitoris
• N: Deep Perineal N.

3. BULBOSPONGIOSUS M.
   - O: Median Raphe, ventral Bulb of Penis and Perineal Body (♂),
   Perineal Body (♀)

• I: Perineal Membrane, fascia of Bulb of Penis and Corpus
  Spongiosum and Corpora Cavernosa of the Penis (♂); fascia of Bulb of the Vestibule of Vagina, Pubic Arch and fascia of the Corpora Cavernosa of the Clitoris (♀)
• A: Support and fix Perineal Body (B); 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 (♂); compresses Vaginal orifice, assist in erection of Bulbs of Vestibule of Vagina and compresses the Greater Vestibular Gland(♀)
• N: Deep Perineal N.

Question 3

Urogenital Diaphragm Description

Answer 3

• This muscle layer is described as being deep to and separated from the Superficial Perineal muscles by the Perineal Membrane; however, may contain elements of the SUPERFICIAL PERINEAL MUSCLES and the PERINEAL MEMBRANE

Question 4

Urogenital Diaphragm

Answer 4

1. EXTERNAL URETHRAL SPHINCTER M. (Sphincter Urethrae M.)
   - O: Surrounds the Urethra

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

A). COMPRESSOR URETHRAE M. (extends laterally from the External Urethral Sphincter)
- O: Ischiopubic Ramus and Ischial Tuberosity

• I: Median Raphe and Urethra via External Urethral
  Sphincter M.
• A: Constrict Urethra maintaining urinary continence N: Dorsal Nerve of the Penis (♂) or Clitoris (♀)

B). URETHROVAGINAL SPHINCTER M. (♀; slips of the External Urethral Sphincter M. that also surround the Vagina)
- O: Ischiopubic Ramus and Ischial Tuberosity

• I: External wall of the Vagina
• A: Compresses the Vagina
• N: Dorsal Nerve of the Clitoris (♀)

2. DEEP TRANSVERSE PERINEAL M. (♂)
   - O: Ischiopubic Ramus and Ischial Tuberosity

• I: Median Raphe, Perineal Body and External Anal Sphincter
• A: Support and fix Perineal Body, supports Abdominopelvic
  Viscera and resists increases in Intraabdominal Pressure
• N: Deep Perineal N.

Question 5

Helpful Hint: The Deep Transverse Perineal Muscle

Answer 5

• The Deep Transverse Perineal M. in the FEMALE is described as being SMOOTH MUSCULAR MASS along the POSTERIOR edge of the Perineal Membrane.

Question 6

Anal Muscles

Answer 6

1. EXTERNAL ANAL SPHINCTER M. (Skeletal Muscle)
   - O: Skin and fascia surrounding Anus and Anococcygeal Body

• I: Perineal Body
• A: Constricts the Anal Canal during Peristalsis, resists Defecation, supports and fix Perineal Body
• N: Inferior Rectal N.

2. INTERNAL ANAL SPHINCTER M. (Smooth Muscle)
   - Involuntary Sphincter surrounding superior 2/3 of Anal Canal, thickening of circular muscular layer innervated by parasympathetic fibers from Pelvic Splanchnic
   nerves

Question 7

Helpful Note: Pelvic Diaphragm

Answer 7

• The Pelvic Diaphragm is made up of four muscles: the three LEVATOR ANI Ms. (Puborectalis M., Pubococcygeus M., and Iliococcygeus M.) and the COCCYGEUS M.
• The Superficial Fascia of the Pelvic Diaphragm also contains small slips of muscle that insert onto the Urinary Bladder, those muscles are the PUBOVESICALIS M. from the Pubis to the Urinary Bladder and the RECTOVESICALIS M. from the Rectum to the Urinary Bladder.

Question 8

Pelvic Diaphragm

Answer 8

1. LEVATOR ANI M.
   A). PUBORECTALIS M. (thick, narrow, medial most part of the LevatorAni)
   - O: Posterior aspect of the Pubic Body

• I: External wall of the Rectum and Anal Canal
• 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

B). PUBOCOCCYGEUS M. (thin, wide, main part of the Levator Ani)
- O: Posterior aspect of the Pubic Body and anterior most part of the Tendinous Arch of Obturator Fascia

• I: Coccyx, Anococcygeal Body, contralateral Pubococcygeus M.
• 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

C). ILIOCOCCYGEUS M. (posterior, thin, poorly developed part of the Levator Ani)
- O: Posterior part of the Tendinous Arch of Obturator fascia and Ischial Spine

• I: Coccyx and Anococcygeal Body
• 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

2. COCCYGEUS M.
   - O: Ischial Spine

• I: Inferior Sacrum and Coccyx
• A: Support Pelvic Viscera, flexes Coccyx
• N: Nerve to the Coccygeus (S4,5; branches of the Coccygeal
  Plexus)

Question 9

Helpful Note: Pubococcygeus Muscle

Answer 9

• The Pubococcygeus M. produces several small slips of muscle that extend to nearby structures, all sharing similar action and innervation as the Pubococcygeus M.
• These muscles include the Levator Prostatae M. (♂), the Pubovaginalis M. (♀) and the Puboperinealis M. and Puboanalis M. in both.

Question 10

Lateral Pelvic Wall Muscles (also associated with the Gluteal Region of the Lower Extremity)

Answer 10

1. OBTURATOR INTERNUS M.
   - O: Pelvic surfaces of the Ilium and Ischium and Obturator Membrane

• I: Greater Trochanter of the Femur
• A: Rotate Thigh laterally, stabilize the Femoral Head in the
  Acetabulum
• N: Nerve to the Obturator Internus M.

2. PIRIFORMIS M.
   - O: Pelvic surface Sacral segments S2-S4, Greater Sciatic
   Notch and Sacrotuberous L.

• I: Greater Trochanter of Femur
• A: Rotate Thigh laterally, abduct Thigh, stabilize Femoral Head
  in Acetabulum
• N: Nerve to the Piriformis M.