Peripheral Nerve Lesions

Upper Limb

Radial nerve   Sites   Arm   Anatomy   Tracks along humerous in the radial groove Supplies all muscles of posterior arm & forearm compartement Mechanisms   Humeral fractures Wrongly used axillary crutches Falling asleep with arm resting on object Clinical Features   Characteristic deformity   "Wrist drop" deformity Paralysis or weakness of metacarpophalangeal extensors Pathomnemonic paraesthesia   Tingling, pain or numbness over anatomical snuffbox Median nerve   Sites   Wrist   Anatomy   Tracks through carpal tunnel Superior branch doesn't pass carpal tunnel - sensation to palm Supplies all muscles of anterior forearm compartement, except those supplied by Ulnar nerve Mechanisms   Carpal tunnel syndrome Wrist slashes Window punches Pregnancy - through fluid retention Rheumatoid arthritis of wrist Colles' fracture Clinical Features   Characteristic deformity   Wasting of thenar eminance Paralysis or weakness of Abductor Pollicis Brevis - test thumb abduction Paralysis or weakness of Flexor Pollicis Longus - test thumb distal phalanx flexion Paralysis or weakness of Flexor Digitorum Profundus - test distal phalanx flexion "Benedictine" deformity Pathomnemonic paraesthesia   Tingling, pain or numbness over palmar aspect of thumb Ulnar nerve   Sites   Elbow   Anatomy   Tracks posterior to medial epicondyle Supplies Palmaris Brevis, Flexor Carpi Ulnaris, Flexor Digitorum Profundus (ulnar 2 digits), interossei muscles Mechanisms   Humeral fractures Osteoarthritis of elbow Falling asleep with arm flexed Clinical Features   Characteristic deformity   "Claw hand" deformity Paralysis or weakness of FDP - test distal phalanx flexion of little finger Paralysis or weakness of interossei - test finger abduction & adduction Pathomnemonic paraesthesia   Tingling, pain or numbness over hypothenar eminence Ulnar nerve paradox   The more distal the lesion, the more pronounced the clawing, due to loss of function of Flexor Digitorum Profundus, causing less flexion at the metacarpophalangeal joints

Lower Limb

Sciatic nerve   Sites   Hip   Mechanisms   Posterior hip dislocation Clinical Features   Characteristic deformity   "Foot drop" deformity Weakness of knee flexion (hamstrings) Absent ankle jerk and plantar reflexes Paraesthesia   Poterior thigh, lateral & posterior calf Common peroneal nerve   Sites   Knee   Anatomy   Tracks along fibular neck Mechanisms   Fibular fracture Clinical Features   Characteristic deformity   "Foot drop" deformity High stepping gait Paralysis or weakness of foot dorsiflexion and eversion Paraesthesia   Tingling, pain or numbness over lateral aspect of dorsum of foot