AN49.1-5 | Perineum — Glossary

Strong triangular fibromuscular sheet spanning the urogenital triangle between the ischiopubic rami; forms the floor of the deep pouch and roof of the superficial pouch

Space between Colles' fascia below and perineal membrane above; contains erectile tissue, superficial perineal muscles, and Bartholin's glands (female)

Space between perineal membrane below and pelvic diaphragm above; contains deep transverse perinei, external urethral sphincter, and bulbourethral glands (male)

Central fibromuscular node of the perineum where five muscles converge; the keystone of pelvic floor integrity

Superficial perineal fascia continuous with Scarpa's fascia of the abdomen; limits urinary extravasation to the scrotum and anterior abdominal wall

Fat-filled wedge-shaped space on each side of the anal canal; site of perianal abscesses

Pudendal canal — fascial tunnel in the lateral wall of the ischiorectal fossa containing the pudendal nerve and internal pudendal vessels

Pectinate line in the anal canal; divides internal from external haemorrhoids and marks the embryological junction of endoderm and ectoderm

Clinical rule predicting fistula-in-ano track direction: anterior external openings have straight tracks; posterior external openings curve to the posterior midline

Classification of fistula-in-ano by relationship to the external anal sphincter: intersphincteric, trans-sphincteric, suprasphincteric, extrasphincteric

Surgical incision of the perineum during childbirth to enlarge the vaginal opening; mediolateral (preferred in India) or midline

Greater vestibular glands in the female superficial perineal pouch; pea-sized mucus-secreting glands at the posterolateral vaginal introitus

Cowper's glands in the male deep perineal pouch; secrete pre-ejaculatory mucus into the bulbar urethra

Voluntary striated muscle sphincter in the deep perineal pouch; innervated by the pudendal nerve (S2-S4)

Infection in the ischiorectal fossa, often from infected anal glands at the dentate line; requires surgical drainage

Longitudinal tear in the anal mucosa below the dentate line, most commonly at the posterior midline due to poor blood supply

External skin tag at the lower end of a chronic anal fissure; a clinical marker of chronicity

Anterior half of the perineal diamond bounded by the pubic symphysis and ischiopubic rami; contains the perineal pouches

Posterior half of the perineal diamond bounded by the ischial tuberosities, sacrotuberous ligaments, and coccyx; contains the anal canal and ischiorectal fossae

S2-S4 nerve that supplies sensory and motor innervation to the entire perineum; travels through Alcock's canal

Deep fascia of the penis investing the corpora cavernosa and corpus spongiosum; limits extravasation in penile urethral rupture

Perianal abscess that communicates across the midline behind the anal canal through the posterior recess of the ischiorectal fossa

Muscle in the superficial perineal pouch that covers the bulb of the penis (male) or vestibular bulbs (female); aids in urination and ejaculation