What are the four main muscles of the pelvis?

The four key muscles are the obturator internus, piriformis, levator ani, and coccygeus. They form the lateral and posterior walls, and the pelvic floor (pelvic diaphragm).

What is the function of the levator ani muscle?

The levator ani forms the pelvic diaphragm and functions to support pelvic viscera, resist intra-abdominal pressure during straining, and act as a sphincter around the anorectal junction and vagina in females.

Where does the obturator internus muscle insert?

The obturator internus inserts onto the medial surface of the greater trochanter of the femur, with its tendon passing through the lesser sciatic notch.

What actions do the piriformis and obturator internus muscles perform?

Both the piriformis and obturator internus stabilize the hip joint, laterally rotate the femur when extended, and abduct the femur when the hip is flexed.

What is the nerve supply for the coccygeus muscle?

The coccygeus is innervated by the ventral rami of S4 and S5 spinal nerves.

How does the levator ani muscle differ in its insertion points?

The levator ani inserts in three ways: anterior fibres loop around the prostate or vagina to the perineal body, intermediate fibres form a sling around the anorectal junction to the anococcygeal raphe, and posterior fibres insert into the anococcygeal raphe and coccyx.

What is the role of the pelvic diaphragm?

The pelvic diaphragm, composed of the levator ani and coccygeus muscles, separates the pelvic cavity from the perineum, supports pelvic organs, and assists in controlling urination and defecation by resisting pressure changes.

Pelvic Muscles – Pelvic Diaphragm & Wall Muscles

❓ Frequently Asked Questions