Anatomy and Pathology of the Upper Limb
What you must know
Know the brachial plexus (roots C5–T1, trunks, divisions, cords, terminal branches) and key peripheral nerves: median (carpal tunnel, pronator teres, anterior interosseous), ulnar (cubital tunnel, Guyon's canal), and radial (spiral groove, posterior interosseous). Understand myotomes and dermatomes, the rotator cuff (supraspinatus, infraspinatus, subscapularis, teres minor) and its actions, ligament and capsule anatomy of the wrist and hand, and common pathologies: rotator cuff tendinopathy/tear, adhesive capsulitis, lateral/medial epicondylalgia, carpal tunnel syndrome, De Quervain tenosynovitis, Dupuytren contracture, trigger finger, and complex regional pain syndrome. Link nerve lesion to expected motor and sensory loss.
Traps in questions
- Ulnar vs median hand deficits: ulnar affects intrinsic muscles and the little finger; median affects thumb opposition and the lateral digits.
- Radial nerve at the spiral groove causes wrist drop with preserved elbow extension; a posterior interosseous lesion spares wrist extension but loses finger extension.
- Supraspinatus initiates abduction; deltoid sustains it - a frequent swap.
- Dupuytren is a palmar fascial contracture (not tendon); trigger finger is a flexor pulley/tendon sheath problem.
- CRPS is diagnosed clinically (disproportionate pain, autonomic and trophic changes), not by a single test.
Rule of thumb
Map the deficit to a nerve, then to a level: sensory loss + weak muscles in one nerve territory points to a peripheral lesion; a dermatomal pattern points to a root.
Worked example
A patient has numbness of the thumb, index, and middle fingers with weak thumb opposition and thenar wasting. This is a median nerve lesion at the wrist (carpal tunnel). Sparing of the little finger and absence of forearm symptoms help localize it.