**Question:** Nerve supply of adductor pollicis is by -

**Core Concept:** Adductor pollicis is a muscle in the hand that helps to flex the thumb towards the palm, and its innervation is crucial to understand its function and potential injuries.

**Why the Correct Answer is Right:**

The correct answer is "C." The adductor pollicis muscle is supplied by the ulnar nerve (C8, T1). The ulnar nerve arises from the cervical spinal cord segments C8 and T1 and is a mixed nerve containing both sensory and motor fibers.

**Why Each Wrong Option is Incorrect:**

A. "Upper lumbar nerves (L1-L3)" (Option A) is incorrect because the adductor pollicis receives its innervation from the ulnar nerve, not the lumbar nerves. The lumbar nerves, L1-L3, supply the lower limbs and do not innervate the hand muscles.

B. "Radial nerve (C5-C7)" (Option B) is incorrect because the radial nerve supplies the muscles of the lateral aspect of the forearm and not the adductor pollicis muscle. The adductor pollicis is supplied by the ulnar nerve.

D. "Median nerve (C5-C8, T1)" (Option D) is incorrect because the median nerve supplies the muscles on the medial aspect of the forearm and not the adductor pollicis muscle. The adductor pollicis is supplied by the ulnar nerve.

C. "Ulnar nerve (C8, T1)" (Correct Answer) is right because the ulnar nerve, originating from C8 and T1 spinal cord segments, supplies the adductor pollicis muscle, allowing proper function and protection of the thumb.

**Clinical Pearl / High-Yield Fact:**

Understanding the spinal cord segments of nerves is essential for recognizing potential nerve injuries and their corresponding clinical presentations. In cases of suspected ulnar nerve injury, the patient may exhibit symptoms such as weakness or paresthesia in the distribution of the affected nerve, including the adductor pollicis muscle.

**Correct Answer:** C. Ulnar nerve (C8, T1)