Anatomy study note · Perineum
Pudendal nerve
The nerve of the perineum, a branch of the sacral plexus (S2–S4). It supplies the external anal sphincter, the perineal muscles and the skin of the perineum and external genitalia.
Key points
- S2–S4 (sacral plexus).
- Out via greater, back in via lesser sciatic foramen, round the ischial spine.
- Pudendal canal on the lateral wall of the ischioanal fossa.
- Branches: inferior rectal, perineal, dorsal nerve of penis/clitoris.
- Block at the ischial spine.
- Ventral root: basal-lamina neurons. Dorsal root: neural-crest ganglion cells.
- Schwann cells: neural crest.
- Nerve: epineurium → perineurium (blood–nerve barrier) → endoneurium.
- Cut nerve: Wallerian degeneration; regrows 0.5–3 mm/day.
The full note in the atlas also covers
Course · Branches · Histology · Development · Clinical notes
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Written from
- Snell’s Clinical Anatomy by Regions, 10th ed., ch. 10, PDF pp. 1178–1180, 1222; ch. 8, PDF pp. 1047–1048
- Inderbir Singh’s Human Embryology, ch. 17, PDF pp. 318, 321, 323–325
- BRS Cell Biology & Histology, 7th ed., ch. 9, PDF pp. 163–166, 171–172
More from the perineum
- Superficial transverse perineal muscle
- Dorsal vessels of the penis
- External anal sphincter
- Male urethra
- Penis
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