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Quick Facts

Location: Perineum.

Arterial Supply: Inferior rectal artery.

Venous Drainage: Inferior rectal vein.

Innervation: Pudendal nerve.

Lymphatic Drainage: Superomedial superficial inguinal lymph nodes.

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The anus is the distal and external opening of the gastrointestinal tract. At its distal end, the epithelium becomes continuous with the skin of the perineum.

Anatomical Relations

The anus is encircled by an area of pigmented skin which roughly matches the area of the external anal sphincter.


The anus provides an opening for the elimination of fecal matter from the gastrointestinal tract.

Arterial Supply

It is supplied by the inferior rectal arteries which are branches of the internal pudendal arteries.

Venous Drainage

The inferior rectal veins accompany the arterial supply and drain into the internal pudendal veins.


The inferior rectal branch of the pudendal nerves (S2-4) provides sensory innervation to the anus. Visceral sensation from the perineum and anus travels back to the CNS via the ganglion impar (Standring, 2016).

Lymphatic Drainage

The superomedial superficial inguinal lymph nodes drain lymph surrounding the anus (Földi et al., 2012).

List of Clinical Correlates

- Hemorrhoids


Földi, M., Földi, E., Strößenreuther, R. and Kubik, S. (2012) Földi's Textbook of Lymphology: for Physicians and Lymphedema Therapists. Elsevier Health Sciences.

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series: Elsevier Limited.

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