A 60-year-old male presents to the emergency department with an anterior shoulder dislocation. After successful reduction, he complains of numbness and tingling along the lateral aspect of his arm and weakness in shoulder abduction. Which nerve is most likely injured in this scenario?

Explanation

The axillary nerve (C5, C6) is the most commonly injured nerve in anterior shoulder dislocations, especially in older patients. It wraps around the surgical neck of the humerus and is vulnerable to stretch or compression during dislocation. Its motor function includes innervation of the deltoid (responsible for shoulder abduction) and teres minor. Its sensory distribution is over the lateral aspect of the shoulder and upper arm, often referred to as the 'regimental badge area'. The symptoms described (weakness in abduction and numbness in the lateral arm) are classic for axillary nerve injury.