This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Nerve supply above pectinate line is through ? 
Select and explain. 
A. Inferior rectal nerve, B. Pudendal nerve, C. Autonomic nerves, D. Perineal branch of S4
C: Autonomic nerves
Answer: C: Autonomic nerves 
Explanation: Nerve supply of anal canalMucous membrane above pectinate line is supplied by autonomic nerves (sympathetic L1 L2 and parasympathetic: S2 S3 S4) and therefore is insensitive to pain.Pa below the pectinate line is supplied by somatic nerves (inferior rectal nerve a branch of pudendal nerve) and therefore is sensitive to pain.Thus pain sensations are carried by pudendal nerve.