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Superficial external anal sphincter - ...

Other Terms: External sphincter ani, Sphincter ani externus, Musculus sphincter ani externus, Sphincter externe de l'anus

Muscle parts

Subcutaneous part, Superficial part; Deep part

Latin name

Musculus sphincter ani externus

Latin muscle parts

Pars subcutanea, Pars superficialis; Pars profunda

Group

Pelvis/perineal wall – lateral musculature – middle and external layers

Etymology

The English name for this muscle is the outer muscle toward the surface that is around the ring that binds tight. The word sphincter comes from the Greek sphinkter meaning “that which binds tight,” which in turn comes from the Greek verb sphingein meaning “to bind tight.” The word ani is the genitive form of anus, which comes from the Latin for “ring.” This describes the ring-like structure of the anus. The Latin term externus means “outward.” The term superficialis is Latin for “near the surface.” It arises from the Latin superficies meaning “surface”.

Origin

Deep part – Fibers blend in the perineal body with more anterior muscles of the middle layer of the perineum; some fibers blend with pubococcygeus above Superficial part – Fibers blend in the perineal body with more anterior muscles of the external layer of the perineum.

Insertion

Deep part - End of the coccyx and onto the anococcygeal ligament. Superficial part - End of the coccyx and onto the anococcygeal ligament.

Action

Narrows the anal canal.

Nerve supply

Pudendal nerve (S2 and S3) or from small direct branches of sacral ventral rami (S2 and S3)

Blood supply

Internal pudendal artery from the internal iliac artery.

Latin

Musculus sphincter ani externus

French

Sphincter externe de l'anus

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