II.D.2 Pelvis & Perineum: Urogenital & Pelvic Diaphragms

Urogenital & Pelvic Diaphragms: Page 2 of 5

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Add the coccygeus.

Review the functions of the muscles in this area in the GI Block reading SB and Colon Part 1 - Section B - Subsections e and f.

Also see Gray's Anatomy page 454: Green box 'Defecation'

	Add the internal anal sphincter.
	Rotate the pelvis to see where the levator ani joins the obturator internus. Identify this juncture in the pelvis. This is called the tendinous arch and delineates the lateral aspect of the pelvis from the pelvic floor.
	Rotate the pelvis to see the perineum.

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Using the Draw tool, draw a line between the ischial tuberosities. This separates the posterior muscular pelvic diaphragm, which controls defecation, from the urogenital triangle which contains the vaginal and the urethral openings.

	What are the landmarks that delineate the urogenital triangle?
The apex of the triangle is the pubic symphysis. The base of the triangle is the imaginary line connecting the two ischial tuberosities. Use the Draw tool to complete the urogenital triangle.