LESIONS OF BRANCHES OF THE BRACHIAL PLEXUS
•Sensory deficits precede motor weakness
•Proximal lesions: more signs
Radial Nerve
Axilla: (Saturdaynightpalsy orusing crutches)
•Loss of extension at the elbow, wrist and MP joints
•Weakened supination
•Sensory loss on posterior arm, forearm, and dorsum of thumb
•Distal sign is "wrist drop."
Mid-shaffofhumerus atradialgroove orlateral elbow (lateral epicondyle orradial head dislocation)
•Loss of forearm extensors of the wrist and MP joints
•Weakened supination
•Sensory loss on the posterior forearm and dorsum of thumb
•Distal sign is "wrist drop!'
Note: Lesions ofradial nerve distal to axilla, elbow extension are spared.
Wrist: laceration
•No motor loss
•Sensory loss only on dorsal aspect of thumb (first dorsal web space)
Median Nerve
Elbow: {Supracondylarfracture ofhumerus)
•Weakened wrist flexion (with ulnar deviation)
•Loss of pronation
• Loss of digital flexion of lateral 3 digits resulting in the inability to make a complete fist; sign is "hand of_benediction"
•Loss of thumb opposition (opponens pollicis muscle); sign is ape (simian) hand
•Loss of first 2 lumbricals
•Thenar atrophy (flattening of thenar eminence)
•Sensory loss on palmar surface of the lateral hand and the palmar sur faces of the lateral 3V2 digits
Note: A lesion of median nerve at elbowresults in the "hand ofbenediction" and "ape hand:'
Wrist: carpal tunnel orlaceration
•Loss of thumb opposition (opponens pollicis muscle); sign is ape or simian hand
•Loss of first 2 lumbricals