Muscles of the Pelvic Floor and Perineum

The pelvic diaphragm is formed by two paired muscles: the levator ani and the coccygeus. The levator ani is the largest component, comprising three parts—the pubococcygeus, puborectalis, and iliococcygeus. These muscles attach to the internal walls of the true pelvis and mark the inferior margin of the abdominopelvic cavity.

The levator ani primarily supports pelvic organs such as the bladder and acts as a sphincter at the anorectal junction, urethra, and vagina. It maintains continence and aids in childbirth by stretching and expanding as needed. This muscle also contributes to core stability and sexual function.

The perineum is a diamond-shaped region beneath the pelvic diaphragm divided into two triangles. The anterior urogenital triangle houses the external genitals and contains the superficial transverse perineal, bulbospongiosus, and ischiocavernosus muscles. The posterior anal triangle contains the anus and external anal sphincter.

The bulbospongiosus muscle surrounds the vaginal or penile areas to assist in sexual functions and provide support. Located in the urogenital triangle, it is part of the superficial perineal layer that helps maintain continence and supports overall pelvic floor stability.

The ischiocavernosus muscle helps maintain erection in both males and females by compressing the outflow veins of erectile tissues. This superficial perineal muscle works with other urogenital triangle muscles to support sexual function, maintain continence, and provide pelvic floor stability.

The obturator internus supports the pelvic organs and aids in lateral rotation of the thigh. Located near the anal triangle, it works alongside the external anal sphincter and the inferior levator ani to provide additional support and stability to the pelvic floor.

The coccygeus muscle extends from the ischial spine to the lower end of the sacrum and coccyx, complementing the levator ani by providing additional support and stability to the pelvic floor. Together, these muscles form a sling-like structure that supports pelvic organs and maintains continence.