LC2.10: MALE PERINEUM
03/03/08
OVERVIEW
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The perineum lies inferior to the pelvic floor and superior to the pelvic outlet
o It is divided into two regions separated by an imaginary line joining the ischial tuberosities
o The anterior region is the urogenital triangle
o The posterior region is the anal triangle
ANAL TRIANGLE
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The anal triangle runs from the coccyx posteriorly to the ischial tuberosities anteriorly forming an
inverted triangle
It is bounded laterally by the sacrotuberous ligaments and is lined internally with levator ani muscle
The anal aperture is surrounded by the external anal sphincter in the midline of the triangle
o The perineal body extends anteriorly from it to the anterior border
o The anococcygeal body extends posteriorly from it to the coccyx
UROGENITAL TRIANGLE
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The urogenital triangle runs from the ischial tuberosities posteriorly to the pubic symphysis anteriorly
It is bounded laterally by the ischiopubic rami and is lined internally with the perineal membrane
Running between the ischial tuberosities is a strip of superficial transverse perineal muscle
Against the ischiopubic rami on either side run ischiocavernosus muscles
Medially along the bulb of the penis runs bulbospongiosus muscle
SUPERFICIAL PERINEAL POUCH
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The superficial perineal pouch is formed between the perineal membrane and the superficial fascia
Contained within the superficial pouch are:
o Perineal muscles – ischiocavernosus, bulbospongiosus and superficial transverse perineal
o Erectile tissues – crura of the penis, bulb of the penis – collectively the root of the penis
DEEP PERINEAL POUCH
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The deep perineal pouch is formed between the perineal membrane and levator ani
Contained within the deep pouch are:
o Perineal muscles – deep transverse perineal
o Bulbourethral glands
o Membranous urethra
o External urethral sphincter
PUDENDAL NERVE
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The pudendal nerve is the major nerve of the perineum
o Arises from sacral plexus at S2, S3 and S4
o Exits the pelvic cavity through the greater sciatic foramen
o Enters the perineum through the lesser sciatic foramen
o Travels along the pudendal canal in the fascia of obturator internus
Its branches are:
o Inferior rectal nerve – to external anal sphincter; sensory to skin of anal triangle
o Perineal nerves – to perineal muscles; largest branch posterior scrotal nerve
o Dorsal nerve of the penis – to deep perineal pouch and glans penis