The Perineum (Rapid Revision)

TISSUE LAYERS OF THE UROGENITAL TRIANGLE: MALE

• Skin
• Subcutaneous Tissue -- Camper's Fascia.
• Superficial Membranous Fascia: Attach to the posterior aspect of the UG diaphragm, just anterior to the central tendon of the perineum.
• Scarpa's Fascia: Abdominal superficial membranous fascia.
• Colle's Fascia: Superficial membranous fascia, continuous with Scarpa's, in the region posterior to the scrotum.
• Darto's Fascia: Superficial membranous fascia of the penis.

• SUPERFICIAL PERINEAL SPACE: All structures between the superficial membranous fascia and the perineal membrane.
• Investing Fascia: Inferior border of the bulbospongiosus muscle. Converges with Buck's fascia at the base of the penis.
• Buck's Fascia: Superior (deep) border of the bulbospongiosus muscle. Converges with investing fascia at the base of the penis.
• True Suspensory Ligament of the Penis: Superior to and continuous with deep fascia, continuous with transversus abdominis fascia of anterior abdominal wall.

MUSCLES / CORPORA / VESSELS / NERVES: All are in the superficial perineal space.

ALL OF THE MUSCLES ATTACH TO THE PERINEAL BODY

• Corpus Spongiosum with Bulbospongiosus Muscle covering it.
• Corpus Cavernosum with Ischiocavernosus Muscles covering it; Crura of the Penis (composed of Corpora Cavernosa).
• Bulb of the penis (of the corpus spongiosum)
• Superficial Transverse Perineal Muscle: The posterior border of the UG diaphragm. Attaches to the perineal body and counters the action
• of the bulbospongiosus muscle.
• It generally holds the UG structures in place.
• Perineal Nerves, branches of the pudendal.

PERINEAL MEMBRANE: Inferior border of the UG diaphragm. It divides the superficial perineal space from the deep perineal space.

DEEP PERINEAL SPACE

Male Muscles of the UG Diaphragm:

Sphincter Urethrae Muscle: To stop urination.

• Primary musculature in the male. They are circular fibers which compress the urethra upon contraction, to stop urination.
• Deep transverse perineal muscle: Muscle located in the posterior aspect of the UG diaphragm.
• Deep dorsal vein/artery of the penis (branch of pudendal vein)
• Deep dorsal nerve of penis (branch of pudendal nerve)
• Bulbourethral (Cowper's) glands -- in the Deep Perineal Space.
• Urethra passes through it.

SUPERIOR MEMBRANE OF THE UROGENITAL DIAPHRAGM

• STRADDLE INJURY: Blood investing the superficial perineal space will not get into the deep perineal space. It will be stopped at the following borders:
  
• Superior Border: Arcuate line in the abdominal wall.
• Lateral Borders: Inguinal Ligaments.
• Deep border: Perineal Membrane.
  

TISSUE LAYERS OF THE UROGENITAL TRIANGLE: FEMALE

• Skin
• Subcutaneous Tissue -- Camper's Fascia.
• Superficial Membranous Fascia: Attach to the posterior aspect of the UG diaphragm, just anterior to the central tendon of the perineum.
• Scarpa's Fascia: Abdominal superficial membranous fascia.
• Colle's Fascia: Superficial membranous fascia, continuous with Scarpa's, in the region posterior to vagina.

SUPERFICIAL PERINEAL SPACE: All structures between the superficial membranous fascia and the perineal membrane.

• Gallaudet's (Deep) Fascia: Inferior border of the bulbospongiosus muscle.
• True Suspensory Ligament of the Clitoris: Superior to and continuous with deep fascia, continuous with transversus abdominis fascia of anterior abdominal wall.

MUSCLES / CORPORA / VESSELS / NERVES: All are in the superficial perineal space.

ALL OF THE MUSCLES ATTACH TO THE PERINEAL BODY

• Two Vestibular Bulbs with Bulbospongiosus Muscle covering it.
• Corpus Cavernosum with Ischiocavernosus Muscles covering them; Crura of the clitoris.
• Urethra / Vagina
• Greater Vestibular (Bartholin's) Gland -- located at the posterior aspect of the vestibular bulb -- in the superficial perineal space.
• The analogous structure in the male, the Bulbourethral gland, is in the deep perineal space, while the female homolog is in the superficial perineal space. Note difference.

Superficial Transverse Perineal Muscle: The posterior border of the UG diaphragm.

• Attaches to the perineal body and counters the action of the bulbospongiosus muscle.
• It generally holds the UG structures in place.
• Perineal Nerves, branches of the pudendal nerve.

PERINEAL MEMBRANE: Inferior border of the UG diaphragm. It divides the superficial perineal space from the deep perineal space.

DEEP PERINEAL SPACE

Female Muscles of the UG Diaphragm:

• Compressor Urethrae Muscle -- passes anterior to the urethra.
• Sphincter Urethrae Muscle -- Passes posterior to the urethra and blends fibers with the compressor urethra.
• It inserts on the Perineal Body.

Urethrovaginal Sphincter -- circular, voluntary fibers around the posterior of the urethra. When they contract, both the vagina and the urethra constrict.

• It inserts on the Perineal Body.
• Deep Transverse Perineal Muscle
• Deep dorsal vein/artery of the clitoris (branch of pudendal vein)
• Deep dorsal nerve of clitoris (branch of pudendal nerve)
• Urethra passes through it.

SUPERIOR MEMBRANE OF THE UROGENITAL DIAPHRAGM

• Genital Hiatus of the UG-Diaphragm: Located in between the arcuate ligament and transverse perineal ligament.
• Arcuate Ligament: Anterior border of genital hiatus, located just deep to the pubic symphysis.

Transverse Perineal Ligament:

• Posterior border of the genital hiatus, located just anterior to the muscular part of the UG diaphragm.
• It is the fusion of the inferior and superior membranes of the UG diaphragm.
• The Deep Dorsal Vein / Nerve of Penis goes below the genital hiatus.
• The pelvic splanchnic nerves go through the hiatus to join the dorsal nerve on the other side.

Category: Anatomy Notes