Small muscles of hand are supplied by -a) C4b) C5c) C6d) C8e) T1

**Core Concept**
The question is testing the knowledge of the dermatomal distribution of the spinal nerves, specifically the innervation of the small muscles of the hand. The correct answer requires an understanding of the motor innervation of the hand, which is primarily derived from the C8 and T1 spinal nerve roots.

**Why the Correct Answer is Right**
The small muscles of the hand are primarily the thenar and hypothenar muscles, which include the opponens pollicis, abductor pollicis brevis, flexor pollicis brevis, abductor digiti minimi, flexor digiti minimi brevis, and palmaris brevis. These muscles are innervated by the median nerve (C8-T1) and the ulnar nerve (C8-T1). The median nerve provides innervation to the thenar muscles, while the ulnar nerve provides innervation to the hypothenar muscles and the palmaris brevis. The correct answer, C8-T1, reflects the combined contribution of these two nerves to the motor innervation of the small muscles of the hand.

**Why Each Wrong Option is Incorrect**
* **Option A:** C4 is not involved in the innervation of the small muscles of the hand. C4 primarily innervates the muscles of the neck and shoulder region.
* **Option B:** C5 is also not involved in the innervation of the small muscles of the hand. C5 primarily innervates the muscles of the shoulder and upper arm region.
* **Option C:** C6 is not the primary nerve root involved in the innervation of the small muscles of the hand. While C6 does contribute to the innervation of the hand, it is primarily responsible for the innervation of the wrist and forearm muscles.

**Clinical Pearl / High-Yield Fact**
The distribution of the small muscles of the hand is often remembered using the mnemonic "C8-T1" to reflect the combined contribution of the median and ulnar nerves to the motor innervation of these muscles.

**Correct Answer:** C8-T1