Iliococcygeus Muscle

Origin

The iliococcygeus muscle originates from the:

- pelvic aspect of the ischial spine;

- posterior portion of the tendinous arch of levator ani.

Insertion

The fibers of the iliococcygeus muscle travel posteromedially, where:

- its superior fibers insert onto the anterolateral aspect of the coccyx;

- its inferior fibers insert onto the iliococcygeal raphe, which is the midline intersection between the inferior fibers of the left and right iliococcygeus muscles. This raphe blends with the anococcygeal ligament.

Key Features & Anatomical Relations

The iliococcygeus muscle is one of the three muscles that form the levator ani muscle, which itself forms a large part of the pelvic diaphragm. The iliococcygeus is a broad, flat skeletal muscle. It is located:

- medial to the ischium and ischioanal fossa;

- lateral to the urinary bladder, the rectum, and the pubococcygeus and puboanalis muscles.

Actions

As part of the pelvic diaphragm, the iliococcygeus muscle provides structural support to adjacent pelvic structures and elevates the pelvic floor. Its fibers are capable of maintaining a tonic contraction at rest, which relaxes during defecation (Standring, 2016).

List of Clinical Correlates

- Prolapse of pelvic viscera

- Urinary incontinence

- Fecal incontinence

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Actions

As part of the pelvic diaphragm, the iliococcygeus muscle provides structural support to adjacent pelvic structures and elevates the pelvic floor. Its fibers are capable of maintaining a tonic contraction at rest, which relaxes during defecation (Standring, 2016).