**Core Concept**
The surgical neck of the humerus is a common site for fractures, particularly in the elderly population. The surrounding anatomy includes the axillary nerve, which is a branch of the posterior cord of the brachial plexus.

**Why the Correct Answer is Right**
The axillary nerve is responsible for innervating the deltoid muscle and the teres minor muscle, which are crucial for shoulder abduction and external rotation. The nerve runs close to the surgical neck of the humerus, making it vulnerable to injury in the event of a fracture. The axillary nerve arises from the posterior cord of the brachial plexus, specifically from the C5 and C6 nerve roots. Injury to the axillary nerve can result in weakness or paralysis of the deltoid and teres minor muscles.

**Why Each Wrong Option is Incorrect**
* **Option A:** The musculocutaneous nerve is not typically injured in fractures of the surgical neck of the humerus. It innervates the biceps brachii, brachialis, and coracobrachialis muscles, which are not directly related to the surgical neck.
* **Option B:** The radial nerve is not typically injured in fractures of the surgical neck of the humerus. It innervates the extensor muscles of the forearm and wrist, but its course is more lateral and not as closely associated with the surgical neck.
* **Option C:** The median nerve is not typically injured in fractures of the surgical neck of the humerus. It innervates the flexor muscles of the forearm and hand, but its course is more medial and not as closely associated with the surgical neck.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the axillary nerve is at risk of injury in fractures of the surgical neck of the humerus. The nerve can be damaged during surgical repair of the fracture, leading to weakness or paralysis of the deltoid and teres minor muscles.

**Correct Answer:** C.