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anatomy and physiology
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Musculoskeletal, skin, and connective tissue ` anatomy and physiology Musculoskeletal, skin, and connective tissue ` anatomy and physiology section iii 447

Upper extremity nerves
nERVE CaUsEs oF inJURy pREsEntation
Axillary (C5-C6) Fractured surgical neck of humerus Flattened deltoid
Anterior dislocation of humerus Loss of arm abduction at shoulder (> 15°)
Loss of sensation over deltoid and lateral arm
Musculocutaneous Upper trunk compression  biceps (C5-6) reflex
(C5-C7) Weakness of forearm flexion and supination
Loss of sensation over lateral forearm
Radial (C5-T1) Compression of axilla, eg, due to crutches or Wrist drop: loss of elbow, wrist, and finger
sleeping with arm over chair (“Saturday night extension
palsy”)  grip strength (wrist extension necessary for
Midshaft fracture of humerus maximal action of flexors)
Repetitive pronation/supination of forearm, eg, Loss of sensation over posterior arm/forearm and
due to screwdriver use (“finger drop”) dorsal hand
Median (C5-T1) Supracondylar fracture of humerus Ž proximal “Ape hand” and “Pope’s blessing”
lesion of the nerve Loss of wrist flexion, flexion of lateral fingers,
Carpal tunnel syndrome and wrist laceration thumb opposition, lumbricals of index and
Ž distal lesion of the nerve middle fingers
Loss of sensation over thenar eminence and
dorsal and palmar aspects of lateral 3 ⁄2 fingers
1
with proximal lesion
Ulnar (C8-T1) Fracture of medial epicondyle of humerus “Ulnar claw” on digit extension
“funny bone” (proximal lesion) Radial deviation of wrist upon flexion (proximal
Fractured hook of hamate (distal lesion) from lesion)
fall on outstretched hand Loss of wrist flexion, flexion of medial fingers,
abduction and adduction of fingers (interossei),
actions of medial 2 lumbrical muscles
Loss of sensation over medial 1 /2 fingers
1
including hypothenar eminence
Recurrent branch of Superficial laceration of palm “Ape hand”
median nerve (C5-T1) Loss of thenar muscle group: opposition,
abduction, and flexion of thumb
No loss of sensation
Humerus fractures, proximally to distally, follow the ARM (Axillary Ž Radial Ž Median)

C5
C6
Axillary nerve C7
C8
T1 Median nerve
Axillary nerve
Musculocutaneous nerve Ulnar nerve
Intercostobrachial
Radial nerve nerve
Radial nerve Radial nerve
Radial nerve in Medial brachial
spiral groove cutaneous nerve Palm of hand
Median nerve Ulnar nerve Musculocutaneous
nerve Medial antebrachial
cutaneous nerve Median nerve
Radial nerve Ulnar nerve
Radial nerve
Recurrent branch
of median nerve Radial nerve
Dorsum of hand

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