Perineum Anatomy and Subdivision Quiz

Perineum

• The perineum is a shallow compartment bounded by the pelvic outlet and separated from the pelvic cavity by the fascia covering the inferior aspect of the pelvic diaphragm.
• The perineum is divided into two triangles: the urogenital triangle (anteriorly) and the anal triangle (posteriorly).
• The urogenital triangle contains the openings of the urinary and reproductive systems.

Perineal Membrane

• The perineal membrane is a thick fibrous sheet that fills the urogenital triangle.
• It has a free posterior border and is attached laterally to the pubic arch.
• The perineal membrane provides support for external genitalia.

Deep Perineal Pouch

• The deep perineal pouch is a thin region superior to the perineal membrane.
• It is bounded inferiorly by the perineal membrane, superiorly by the inferior fascia of the pelvic diaphragm, and laterally by the inferior portion of the obturator fascia.
• In females, the deep perineal pouch contains the proximal part of the urethra, deep transverse perineal muscles, external urethral muscle, and neurovasculature of the clitoris.

Superficial Perineal Pouch

• The superficial perineal pouch is a potential space between the perineal fascia and the perineal membrane.
• It is bounded laterally by the ischiopubic rami.
• In females, the superficial perineal pouch contains the clitoris and associated muscle, bulbs of the vestibule and surrounding muscle, greater vestibular glands, superficial transverse perineal muscles, and related vessels and nerves.

Vagina

• The vagina is a fibromuscular tube that extends from the vestibule to the uterus.
• It has an anterior wall (approximately 7.5 cm long) and a posterior wall (approximately 9 cm long).
• The vagina opens externally via the vaginal orifice, which is positioned below the urethral orifice.
• The size of the vaginal orifice varies and is capable of great distension during childbirth and to a lesser degree during sexual intercourse.

Hymen

• The hymen is a thin fold of mucous membrane situated just within the vaginal orifice.
• It varies greatly in shape and dimensions, including annular, semilunar, septate, cribiform, and sometimes complete or imperforate.
• The hymen normally ruptures after the first sexual intercourse.

Arterial Supply and Venous Drainage of Vagina

• The arteries supplying the superior part of the vagina derive from the uterine arteries.
• The arteries supplying the middle and inferior parts of the vagina derive from the vaginal and internal pudendal arteries.
• The vaginal veins form vaginal venous plexuses along the sides of the vagina and within the vaginal mucosa.
• The vaginal veins drain into the internal iliac veins through the uterine vein.