Which nerve is most commonly injured in mid- or distal humeral shaft fractures?

Which nerve is most commonly injured in mid- or distal humeral shaft fractures?

• A. Axillary
• B. Median
• C. Radial
• D. Ulnar

Answer: (C)

Radial nerve is most at risk with mid- to distal humeral shaft fractures because it travels along the posterior aspect of the humerus in the radial groove, right where shaft fractures commonly occur. When this nerve is injured there, its motor fibers to the extensor muscles of the wrist and fingers are affected, leading to weakness or inability to extend the wrist and fingers (wrist drop). Sensory loss can occur on the dorsoradial aspect of the hand and across the dorsal surfaces of the thumb and index finger, depending on which branches are involved. The others are less likely in this specific fracture location: the axillary nerve is more often affected by proximal humeral injuries near the shoulder; the median and ulnar nerves are more commonly involved with injuries closer to the elbow or on the medial side. Thus, the radial nerve is the most commonly injured in mid- or distal humeral shaft fractures.

Radial nerve is most at risk with mid- to distal humeral shaft fractures because it travels along the posterior aspect of the humerus in the radial groove, right where shaft fractures commonly occur. When this nerve is injured there, its motor fibers to the extensor muscles of the wrist and fingers are affected, leading to weakness or inability to extend the wrist and fingers (wrist drop). Sensory loss can occur on the dorsoradial aspect of the hand and across the dorsal surfaces of the thumb and index finger, depending on which branches are involved. The others are less likely in this specific fracture location: the axillary nerve is more often affected by proximal humeral injuries near the shoulder; the median and ulnar nerves are more commonly involved with injuries closer to the elbow or on the medial side. Thus, the radial nerve is the most commonly injured in mid- or distal humeral shaft fractures.