Quick Facts
Origin: One of three terminal branches of the pudendal nerve (S2-S4).
Course: Penetrates the fascia of the pudendal canal and courses medially across the ischioanal fossa
Branches: None.
Supply: Motor innervation to external anal sphincter and levator ani and sensory innervation to the skin of the anal triangle.
Related parts of the anatomy
Origin
The inferior anal nerve is one of three terminal branches of the pudendal nerve inside the perineum.
Course
The pudendal nerve travels along the lateral wall of the ischioanal fossa in the pudendal canal to reach the anal triangular region of the perineum. The pudendal canal is a tubular compartment formed in the fascia that covers the obturator internus muscle.
Inside the perineum (in the ischioanal fossa), the pudendal nerve gives off a terminal branch called the inferior anal (or rectal) nerve. The nerve penetrates the fascia of the pudendal canal and courses medially across the ischioanal fossa to innervate the external anal sphincter and related regions of the levator ani muscles. The nerve also supplies general sensory innervation to the skin of the anal triangle (Standring, 2016).
Branches
There are no named branches.
Supplied Structures
The inferior anal nerve provides motor innervation supplies the external anal sphincter and levator ani muscles, while sensory innervation supplies the skin of the anal triangle.
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
