Everyday Muscle.

External Anal Sphincter

Pelvic Floor
The voluntary squeeze muscle for fecal continence — unlike the internal anal sphincter, you're in conscious control of this one. Tested in neurological exams.
Function
Voluntarily closes anal canal
Origin
Perineal body and anococcygeal ligament/coccyx region
Insertion
Encircles anal canal and inserts into perineal body/anococcygeal raphe
Innervation
Inferior rectal nerve from pudendal nerve (S2-S4)
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Pubococcygeus (Superficial) Puborectalis Iliococcygeus Levator Ani Coccygeus (Ischiococcygeus) Transverse Perineal Superficial Transverse Perineal Deep Transverse Perineal Sphincter Urethrae Internal Anal Sphincter