This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen and pelvis, Subject name: Anatomy
External anal sphincter is innervated by 
Select and explain. 
A. L4, L5, B. L5, S1, C. S1, S2, S3, D. S2, S3, S4
D: S2, S3, S4
Answer: D: S2, S3, S4 
Explanation: External anal sphincter is controlled by spinal nerves from the S2, S3 and S4 levels of your spinal cord, which form the pudendal nerve. ref - BDC vol2 pg 412-416