External anal sphincter
| External anal sphincter | |
|---|---|
Coronal section through the anal canal. B. Cavity of urinary bladder V.D. Ductus deferens. S.V. Seminal vesicle. R. Second part of rectum. A.C. Anal canal. L.A. Levator ani. I.S. Sphincter ani internus. E.S. Sphincter ani externus. | |
| Details | |
| Nerve | Branch from the fourth sacral and contributions from the inferior hemorrhoidal branch of the pudendal nerve |
| Actions | Keep the anal canal and orifice closed |
| Identifiers | |
| Latin | sphincter ani externus |
| TA98 | A04.5.04.012 |
| TA2 | 2426 |
| FMA | 21930 |
| Anatomical terms of muscle | |
The external anal sphincter (or sphincter ani externus) is an oval tube of skeletal muscle fibers. Distally, it is adherent to the skin surrounding the margin of the anus. It exhibits a resting state of tonical contraction and also contracts during the bulbospongiosus reflex.