Nerve supply of deltoid is
**Core Concept**
The deltoid muscle is a large muscle of the shoulder region that is responsible for shoulder joint movements, including flexion, extension, and rotation. Its nerve supply is crucial for understanding the motor control and innervation of this muscle.
**Why the Correct Answer is Right**
The deltoid muscle receives its nerve supply from the axillary nerve (C5-C6), which arises from the posterior cord of the brachial plexus. The axillary nerve is responsible for the motor innervation of the deltoid muscle, as well as the teres minor muscle. The axillary nerve also provides sensory innervation to the skin overlying the deltoid muscle and the shoulder joint. The nerve fibers that supply the deltoid muscle are primarily motor fibers, which are responsible for muscle contraction.
**Why Each Wrong Option is Incorrect**
**Option A:** The radial nerve, which is responsible for the innervation of the triceps brachii and anconeus muscles, is not the nerve supply of the deltoid muscle.
**Option B:** The musculocutaneous nerve, which is responsible for the innervation of the biceps brachii and brachialis muscles, is not the nerve supply of the deltoid muscle.
**Option C:** The median nerve, which is responsible for the innervation of various muscles of the anterior forearm and the flexor muscles of the wrist and fingers, is not the nerve supply of the deltoid muscle.
**Clinical Pearl / High-Yield Fact**
The axillary nerve is also responsible for the innervation of the teres minor muscle, which is another muscle of the shoulder region. The axillary nerve is often damaged in shoulder dislocations and surgical procedures, leading to weakness of the deltoid and teres minor muscles.
**Correct Answer: C. Axillary nerve.**