Upper Extremity Dermatomes and Myotomes Motor Function Shoulder: • Abduction - C5,C6 (axillary) • Adduction - C6, C7, C8 Elbow: • Flexion - C5,C6 (musculocutaneous) • Extension C6, C7, C8 (radial) Supination - C6 Pronation - C7, C8 Wrist: • Flexion - C6, C7 (median) • Extension - C7, C8 (radial) Finger: • Mexion - C8 (median) • Extension - C7, C8 (radial) • Abduction - C8-T1 (ulnar) • Adduction - C7-T1 (ulnar) • Thumb opp - C8, T1 (median) Reflexes: • Triceps Jerk - C7, C8 • Biceps Jerk - C5, C6 • Supinator - C5, C6 • Finger Jerk - C8 Important Conditions Erb's Palsy is caused by damage to the upper trunk and results in characteristic "waiter's tip" position. Klumpke's Ralsy - Damage to C8 and T1 leading toc aracteristic "claw hand" ± Horner Syndrome Wrist drop - Occurs after damage to the radial nerve in the radial groove. Triceps power is characteristically spared in this injury. "Saturday night palsy" is a common cause. Carpal Tunnel Syndrome - Causes paraesthesia in the median nerve distribution with atrophy of the thenar eminence. Anterior Shoulder Dislocation - May cause axillary nerve damage resulting in "regimental badge" anesthesia and deltoid weakness. #UpperLimb #Extremity #Dermatomes #Myotomes #diagnosis #neurology #sensory #motor #arm #physicalexam
