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: Surgery
External hemorrhoids are innervated by: 
Select and explain. 
A. Pudendal Nerve, B. Lumbar Nerve, C. Obturator Nerve, D. Gluteal Nerve
A: Pudendal Nerve
Answer: A: Pudendal Nerve 
Explanation: External hemorrhoids are varicosities of the tributaries of the inferior rectal vein. They are covered by the mucous membrane of the lower half of the anal canal. They are innervated by the inferior rectal nerve which is a branch of pudendal nerve. They are sensitive to pain temperature and pressure. Ref: Snell's, Clinical Anatomy, 7th Edition, Page 424.