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ANATOMY
Medicine Made Simple
, Perineum
Diamond shaped region positioned inferior to the pelvic diaphragm between thighs at lower
end of the trunk
Inferior border of pubic symphysis
Urethral opening Urogenital Hiatus
Ischiopubic ramus
Vaginal opening Urogenital triangle
Ischial tuberosity
Anal aperture
Sacrotuberous ligament,
covered by inferior border
Anal triangle of gluteus maximus
Perineum boundaries: - Peripheral – Pelvic outlet
Roof – Pelvic diaphragm
Lateral walls – Pelvic cavity walls below the origin of levator ani
Anterior point – inferior border of pubic symphysis
Posterior point – tip of the coccyx
Lateral points – ischial tuberosity
Lateral borders – Anterior – ischiopubic rami
Posterior – sacrotuberous ligament
Anal tringle Urogenital triangle
Anal canal External genitalia
Ischioanal fossae
Cutaneous supply
1. Inferior rectal nerve 1. Ilioinguinal nerve (L1) - anterior third of the
2. Perineal branch of S4 scrotum (labium majus)
3. Twigs from coccygeal plexus 2. Dorsal nerve of penis (clitoris) (S2) – branch of
pudendal nerve
3. Posterior 2/3rd of scrotum
a. Medially – scrotal branches of the perineal
branches of pudendal neve
b. Laterally – perineal branches of the posterior
cutaneous nerve of thigh
1
ANATOMY
Medicine Made Simple
, Perineum
Diamond shaped region positioned inferior to the pelvic diaphragm between thighs at lower
end of the trunk
Inferior border of pubic symphysis
Urethral opening Urogenital Hiatus
Ischiopubic ramus
Vaginal opening Urogenital triangle
Ischial tuberosity
Anal aperture
Sacrotuberous ligament,
covered by inferior border
Anal triangle of gluteus maximus
Perineum boundaries: - Peripheral – Pelvic outlet
Roof – Pelvic diaphragm
Lateral walls – Pelvic cavity walls below the origin of levator ani
Anterior point – inferior border of pubic symphysis
Posterior point – tip of the coccyx
Lateral points – ischial tuberosity
Lateral borders – Anterior – ischiopubic rami
Posterior – sacrotuberous ligament
Anal tringle Urogenital triangle
Anal canal External genitalia
Ischioanal fossae
Cutaneous supply
1. Inferior rectal nerve 1. Ilioinguinal nerve (L1) - anterior third of the
2. Perineal branch of S4 scrotum (labium majus)
3. Twigs from coccygeal plexus 2. Dorsal nerve of penis (clitoris) (S2) – branch of
pudendal nerve
3. Posterior 2/3rd of scrotum
a. Medially – scrotal branches of the perineal
branches of pudendal neve
b. Laterally – perineal branches of the posterior
cutaneous nerve of thigh
1
