Nerve involved in fracture surgical neck humerus is which of the following?
**Core Concept**
The surgical neck of the humerus is a common site for fractures, which can lead to damage to nearby nerves. The musculocutaneous nerve, axillary nerve, and radial nerve are some of the nerves that run in close proximity to the humerus. Understanding the anatomy of these nerves is crucial for diagnosing and managing nerve injuries associated with humerus fractures.
**Why the Correct Answer is Right**
The axillary nerve is particularly susceptible to injury in fractures of the surgical neck of the humerus. This is because the axillary nerve wraps around the surgical neck of the humerus, making it vulnerable to damage. The axillary nerve arises from the posterior cord of the brachial plexus and supplies the deltoid and teres minor muscles, as well as providing sensory innervation to the skin over the deltoid region. Injury to the axillary nerve can result in weakness of the deltoid muscle, leading to difficulty in abduction of the arm.
**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 is more commonly associated with injuries to the shaft of the humerus or the proximal humerus. The musculocutaneous nerve supplies the biceps brachii, brachialis, and coracobrachialis muscles, which are involved in flexion and supination of the arm.
**Option B:** The radial nerve is also not typically injured in fractures of the surgical neck of the humerus. While it does run close to the humerus, its course is more posterior and is more commonly associated with injuries to the shaft of the humerus or the olecranon. The radial nerve supplies the triceps brachii muscle, which is involved in extension of the elbow.
**Option D:** There is no option D provided.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the axillary nerve is particularly vulnerable to injury in fractures of the surgical neck of the humerus due to its close proximity to the fracture site. A thorough neurological examination, including assessment of deltoid function and sensation over the deltoid region, is crucial in diagnosing axillary nerve injuries.
**Correct Answer: C. Axillary nerve.**