The sphincter urethrae (external urethral sphincter) is a voluntary muscle. In males, which nerve provides its motor innervation?

• A Pelvic splanchnic nerve (S2–S4 parasympathetic)
• B Perineal branch of the pudendal nerve (S2–S4) ✓
• C Obturator nerve
• D Inferior hypogastric plexus (T10–L2 sympathetic)

Explanation

The external urethral sphincter (sphincter urethrae) is a skeletal (voluntary) muscle innervated by the perineal branch (or deep branch) of the pudendal nerve (S2, S3, S4). This is why damage to the pudendal nerve during pelvic surgery or perineal trauma leads to urinary stress incontinence. The internal urethral sphincter is smooth muscle under sympathetic (T10–L2) control via the inferior hypogastric plexus, and its relaxation during micturition is under parasympathetic (S2–S4) influence.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.