Pudendal nerve (S2–S4)
Nerves · S2 S3 S4
Leaves the pelvis through the greater sciatic foramen below piriformis, hooks around the ischial spine and sacrospinous ligament medial to the internal pudendal vessels, re-enters through the lesser sciatic foramen and runs forward in the pudendal (Alcock's) canal on obturator internus in the lateral wall of the ischio-anal fossa.
Traced from the start
Detail
- Branches
- Inferior rectal, perineal, dorsal nerve of the penis or clitoris
- Motor
- External anal sphincter, external urethral sphincter, bulbospongiosus, ischiocavernosus and the other perineal muscles
- Sensory
- Perineum, anal canal below the pectinate line, posterior scrotum or labia, penis or clitoris
- Partner
- Somatic; parasympathetic control of erection and the detrusor comes from the pelvic splanchnics (S2–S4)
When it goes wrong
Stretch in a prolonged second stage of labour or forceps delivery; chronic compression in Alcock's canal (cyclists)
Faecal and stress urinary incontinence, perineal numbness or burning pain that is worse sitting; a pudendal block injected at the ischial spine (transvaginal) anaesthetises the perineum for forceps or episiotomy
Practise this structure
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