Which nerve is at risk with fracture at the surgical neck of the humerus and what deficits occur?

Which nerve is at risk with fracture at the surgical neck of the humerus and what deficits occur?

• A. Axillary Nerve; Weakened Abduction Beyond 15 Degrees and Loss of Sensation Over the Lateral Shoulder
• B. Radial Nerve; Wrist Drop
• C. Median Nerve; Loss of Sensation Over Thenar Eminence
• D. Musculocutaneous Nerve; Elbow Flexion Weakness

Answer: (A)

Fracture at the surgical neck of the humerus puts the axillary nerve at risk because this nerve runs just inferior to the glenohumeral joint in the quadrangular space near the surgical neck. The axillary nerve supplies the deltoid and teres minor. When it’s injured, abduction of the arm beyond the first 15 degrees is weakened because the deltoid is responsible for that range after supraspinatus initiates abduction. There’s also loss of sensation over the lateral shoulder (the regimental badge area) due to the cutaneous branch of the axillary nerve. Other nerves would cause different patterns: a radial nerve injury from a midshaft fracture leads to wrist drop; a median nerve injury would affect sensation over the thenar eminence and hand functions; a musculocutaneous nerve injury would impair elbow flexion and sensory supply of the lateral forearm.

Fracture at the surgical neck of the humerus puts the axillary nerve at risk because this nerve runs just inferior to the glenohumeral joint in the quadrangular space near the surgical neck. The axillary nerve supplies the deltoid and teres minor. When it’s injured, abduction of the arm beyond the first 15 degrees is weakened because the deltoid is responsible for that range after supraspinatus initiates abduction. There’s also loss of sensation over the lateral shoulder (the regimental badge area) due to the cutaneous branch of the axillary nerve.

Other nerves would cause different patterns: a radial nerve injury from a midshaft fracture leads to wrist drop; a median nerve injury would affect sensation over the thenar eminence and hand functions; a musculocutaneous nerve injury would impair elbow flexion and sensory supply of the lateral forearm.