Coccygeus muscle

The coccygeus (coccygeal muscle) is a paired, flat, and triangular muscle located on each side of the pelvic cavity. It forms part of the pelvic diaphragm along with the levator ani muscle. This muscle is also included in the muscles of the tail (separate entry in NAV: Coccygeal muscle). The coccygeus helps support the pelvic viscera and plays a role in tail movement and positioning.

Origin: The coccygeus arises from the ischiatic spine (spina ischiadica).

Insertion: It inserts on the lateral surface of the caudal vertebrae, typically from the 2nd or 3rd to the 5th or 6th caudal vertebra depending on the species.

Innervation: by ventral branches of the sacral spinal nerves, typically S3–S5 in many species. In some texts, it is also reported to receive fibers from the pudendal nerve.

Blood Supply: Supplied by branches from the internal pudendal artery and sometimes directly from the caudal gluteal artery.

Function

• Supports pelvic organs by forming part of the pelvic diaphragm.

• Moves the tail laterally when acting unilaterally.

• Elevates the tail when both sides act together.

• Assists defecation and helps resist increases in intra-abdominal pressure.