Pubococcygeus muscle

At a glance

English

Pubococcygeus muscle

Latin (TA2)

Musculus pubococcygeus

System

Muscle

Region

Trunk

Side

Paired, left and right

About the pubococcygeus muscle

Levator ani, the broad muscle sheet of the pelvic floor, is described in three parts: puborectalis, pubococcygeus and iliococcygeus. Pubococcygeus forms the bulk of its middle section. Its fibres run from the pubic bone at the front of the pelvis to the coccyx at the back, passing either side of the opening through which the urethra and anal canal leave the pelvis.

The muscle arises from the inner surface of the body of the pubis and from the front part of the tendinous arch of levator ani, the thickened line on the fascia over obturator internus. Its fibres pass backward almost horizontally. The more lateral ones join their partners from the other side in the anococcygeal body, the fibrous seam behind the anus, and attach to the front of the coccyx. The more medial fibres form smaller named bundles that end on the organs they pass, such as the pubo-analis, which blends with the anal canal and its sphincters. Puborectalis lies just below and medial to it, and iliococcygeus continues the sheet behind.

With the rest of levator ani, pubococcygeus supports the pelvic organs, holding them up against the rise in abdominal pressure that comes with coughing, lifting and straining. It tightens around the urethra and anal canal and so assists continence, and it draws the coccyx forward. It is active at rest and contracts more strongly with effort; it relaxes during emptying of the bladder and bowel.

Its nerve supply comes from the nerve to levator ani (S3, S4) on its upper surface and from the inferior rectal and perineal branches of the pudendal nerve on its lower surface. Its arteries are branches of the internal iliac artery, including the inferior gluteal and internal pudendal arteries. Weakness of this muscle contributes to stress incontinence and to sagging of the pelvic organs. Pelvic floor muscle training, often called Kegel exercises, aims mainly at strengthening pubococcygeus.

Attachments, action and supply

Origin

Inner surface of the body of the pubis and the anterior part of the tendinous arch of levator ani.

Insertion

Anococcygeal body and the front of the coccyx, with medial fibres to the anal canal.

Action

Supports the pelvic organs, constricts the urethral and anal openings to aid continence, and draws the coccyx forward.

Nerve supply

Nerve to levator ani (S3, S4) and the inferior rectal and perineal branches of the pudendal nerve.

Blood supply

Branches of the internal iliac artery, including the inferior gluteal and internal pudendal arteries.