Pelvic And Perineal Myology Flashcards by Berina Karisik

What is the perineal body?

An irregular fibromuscular mass in the midline between the anal canal and the perineal membrane
Contains collagenous and elastic fibers
Is the attachment point for the bulbospongiosus, external anal sphincter, superficial transverse perineal and deep transverse perineal muscles
Sometimes classified as a central tendon of the pelvic and urogenital diaphragms

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What are the superficial perineal muscles?

Superficial most muscles of the perineum

Includes superficial transverse, ischiocavernosus and bulbospongiosus muscles

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What is the origin and insertion for the superficial transverse perineal muscles?

O: ischiopubic ramus and ischial tuberosity
I: perineal body

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What is the action of the superficial transverse perineal M?

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

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What are all superficial perineal muscles innervated by?

Deep perineal N

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What is the origin and insertion for the ischiocavernosus muscle?

O: ischiopubic ramus and ischial tuberosity
I: medial aspect of the crus of the penis (male) or clitoris (female) and perineal membrane medial to the crura

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What is the action of the ischiocavernosus M?

Maintain erection of penis or clitoris by compressing venous drainage, forcing blood from the crura into the body of the penis or clitoris

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What is the origin of the bulbospongiosus M?

Median raphe, ventral bulb and perineal body (male), perineal body (female)

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What is the insertion for the bulbospongiosus M?

Perineal membrane, fascia of bulb of penis and corpus spongiosum and corpora cavernosa of the penis (males)
Fascia of bulb of vestibule of vagina, pubic arch and fascia of the corpora cavernosa of the clitoris (female)

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What is the action of the bulbospongiosus M?

Support and fix perineal body
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 (males)
Compresses vaginal orifice, assist in erection of bulbs of vestibule of vagina and compresses the greater vestibular glands (female)

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What is the urogenital diaphragm?

Deep to and separated from the superficial perineal muscles by the perineal membrane however it may contain elements of the superficial perineal muscles and perineal membrane

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Which muscles make up the urogenital diaphragm?

External urethral sphincter M including compressor urethrae and urethrovaginal sphincter M +
Deep transverse perineal M

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What is the origin and insertion for the external urethral sphincter M?

Surrounds the urethra

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What is the action of the external urethral sphincter?

Constrict urethra maintaining urinary continence

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Which muscles are innervated by the dorsal N of the penis or clitoris?

External urethral sphincter M, compressor urethrae M

Dorsal N of clitoris only = urethrovaginal sphincter M

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Which what is the origin and insertion for the 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

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What is the action of the compressor urethrae M?

Constrict urethra maintaining urinary continence

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What is the origin and insertion for the urethrovaginal sphincter M?

Slips of the external urethral sphincter M that also surrounds the vagina (in females)
O: ischiopubic ramus and ischial tuberosity
I: external wall of vagina

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What is the action of the urethrovaginal sphincter M?

Compresses the vagina

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What is the origin and insertion of the deep transverse perineal M?

In males
O: ischiopubic ramus and ischial tuberosity
I: median raphe, perineal body, external anal sphincter

What is the action of the deep transverse perineal M?

Support and fix perineal body

Supports abdominopelvic viscera and resists increases in intraabdominal pressure

What innervates the deep transverse perineal M?

Deep perineal N

The deep transverse perineal M in the female is described as being what?

A smooth muscular mass along the posterior edge of the perineal membrane

Which muscles are anal muscles?

External and internal anal sphincter M

What is the origin and insertion of the external anal sphincter M?

O: skin of fascia surrounding anus and anococcygeal body I: perineal body

What is the action of the external anal sphincter M?

Constricts anal canal during peristalsis Resists defecation Supports and fix perineal body

What innervates the external anal sphincter M?

Inferior rectal N

Describe the internal anal sphincter M

Involuntary sphincter surrounding superior 2/3 of anal canal Thickening of circular muscle layer innervated by parasympathetic fibers from pelvic splanchnic nerves

Which 4 muscles make up the pelvic diaphragm?

Levator ani muscles (puborectalis, puboccocygeus and illiococygeus) Coccygeus M

The superficial fascia of the pelvic diaphragm contain what?

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

What is the origin and insertion of the puborectalis M?

Medial most part of levator ani O: posterior aspect of the pubic body I: external wall of rectum and anal canal

What is the action of the puborectalis M?

Maintain and rectal flexure, support pelvic viscera, resist increases in intraabdominal pressure

What innervates all levator ani muscles?

Nerve to the levator ani (S4), inferior rectal N, and branches of the coccygeal plexus

What is the origin and insertion of the pubococcygeus?

Main part of 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 puboccygeus M

What is the action of the pubococcygeus M?

Supports pelvic viscera | Resists increases in intraabdominal pressure

The pubococcygeus M produces small slips of muscle that extend to nearby structures all sharing similar action and innervation as the pubococcygeus M. What are these muscles?

Include the levator prostate M (males), pubovaginalis M (females), and the puboperinealis M and puboanalis in both

What is the origin and insertion of the iliococcygeus M?

Posteriorly thin and 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

What is the action of the iliococcygeus M?

Supports pelvic viscera | Resists increases in intraabdominal pressure

What is the origin and insertion of the coccygeus M?

O: ischial spine I: inferior sacrum and coccyx

What is the action of the coccygeus M?

Support pelvic viscera | Flexes coccyx

What is the coccygeus innervated by?

Nerve to coccygeus (S4/5) and branches of coccygeal plexus

What are the lateral pelvic wall muscles?

Obturator internus and piriformis M

What is the origin and insertion for the obturator internus M?

O: pelvic surfaces of the ilium and ischium and obturator membrane I: greater trochanter of femur

What is the action of the obturator internus?

Rotate thigh lateral | Stabilize the femoral head in the acetabulum

What is the obturator inernus innervated by?

Nerve to the obturator internus

What is the origin and insertion of the piriformis?

O: pelvic surface of sacral segments S2-4; greater sciatic notch and sacrotuberous L I: greater trochanter of femur

What is the action of the piriformis?

Rotate thigh laterally, abduct thigh | Stabilize femoral head in acetabulum

What innervates the piriformis?

Nerve to piriformis