A 24-year-old female basketball player is admitted to the emergency department after an injury to her shoulder. Radiographic examination reveals a shoulder dislocation. What is the most commonly injured nerve in shoulder dislocations?
**Core Concept:**
Shoulder dislocations are injuries to the ball-and-socket joint of the shoulder, resulting from a traumatic event that forces the humeral head out of its glenoid fossa. The most commonly injured nerves during these events are the axillary, suprascapular, and superior lateral glenohumeral nerves.
**Why the Correct Answer is Right:**
In shoulder dislocations, the most commonly injured nerve is the axillary nerve (C5-C6-C7), which originates from the brachial plexus. The axillary nerve supplies motor innervation to the deltoid, teres major, and biceps muscles, which are essential for maintaining the stability of the shoulder joint. Injuries to these nerves can result in a loss of shoulder abduction, external rotation, and flexion, respectively.
**Why Each Wrong Option is Incorrect:**
A. The suprascapular nerve (C4-C5) is involved in shoulder rotation and not primary shoulder stability. Injuries to the suprascapular nerve may cause weakness in infraspinatus and teres minor muscles, resulting in external rotation deficit. However, it is less commonly injured compared to the axillary nerve.
B. The superior lateral glenohumeral nerve (C5-C6) is involved in shoulder abduction and external rotation. Although it is less commonly injured than the axillary nerve, it is still less commonly injured than the axillary nerve.
C. The posterior cord of the brachial plexus (C5-C8) contains the radial nerve, which is involved in wrist and hand function but not shoulder stability.
**Clinical Pearl:**
In cases of shoulder dislocation, a thorough examination for nerve deficits is essential to guide rehabilitation and management strategies. Early recognition and management can prevent long-term complications such as frozen shoulder, muscle atrophy, and joint instability.
**Correct Answer:** D. The axillary nerve (C5-C6-C7) is the most commonly injured nerve during shoulder dislocations due to its role in maintaining shoulder stability through the deltoid, teres major, and biceps muscles.