Perineum part 1 Dr Stuti Tandon Assistant professor

Perineum (part 1) Dr Stuti Tandon Assistant professor Department of anatomy Cims&h

Introduction • Perineum is the lowest region of trunk below pelvic diaphragm. • It is traversed by urethra and anal canal in males. • It is traversed by urethra, vagina and anal canal in females. • Surface features in males: penis, scrotum and anal orifice. • Surface features in females: female external genitalia and anal orifice.

Superficial boundaries Male perineum Female perineum

Deep boundaries

Divisions • The perineum is divided into two triangles by a horizontal plane passing through the anterior end of ischial tuberosities. 1. Anterior urogenital triangle 2. Posterior anal triangle

Anal triangle/posterior perineum

Ischiorectal fossa (ischioanal fossa) • Wedge shaped • Fat filled space • Situated on either side of anal canal • Lies below the pelvic diaphragm • The two fossae communicate with each other behind the anal canal • They help in dilatation of Anal canal during defecation • Base of fossa – skin over the anal region of perineum • Apex directed upwards

• Measurement of fossa • Length 5 cm • Width 5 cm • Depth 5 cm or slightly more

Boundaries

Recesses of ischiorectal fossa

Contents

Clinical correlation Ischiorectal abscess- infection in ischiorectal fossa can occur from boils and abrasions of perianal skin, from lesions within the anal canal, pelvic infection or rarely via blood forming ischiorectal abscess. Infection may pass from one fossa to another behind the anal canal forming horse shoe shaped abscess. Abscess may burst into anal canal leading to anorectal fistula. Abscess may burst on the surface of perineum leading to fistula in ano. Loss of fat in ischiorectal fossa leads to rectal prolapse Pelvic organs may herniate into ischiorectal fossa through a gap between tendinous origin of levator ani and obturator fascia ( hiatus of Schwalbe) Ischiorectal abscess and anorectal fistula