Motor and Sensory Examination

A motor and sensory examination is a localization tool and a safety screen. A complaint such as “my leg feels weak” may arise from the brain, spinal cord, nerve root, peripheral nerve, neuromuscular junction, or muscle; the examination narrows those possibilities before testing is ordered. Three features carry particular weight: distribution, associated signs, and tempo. A hemibody deficit points toward the brain, a sensory level toward the spinal cord, a dermatomal pattern toward a nerve root, and symmetric distal loss toward a length-dependent peripheral neuropathy. Tone, reflexes, atrophy, and the presence or absence of cortical or cranial-nerve findings refine that localization. Sudden onset changes the priority: a new focal deficit is managed as a possible stroke until assessed, while rapidly progressive bilateral weakness raises concern for spinal cord disease, cauda equina syndrome, or Guillain-Barré syndrome. Compare right with left, test in a consistent sequence, and record enough detail to detect change. A single strength grade is less informative than a time-stamped pattern that shows whether weakness, sensory loss, reflex change, or respiratory function is progressing.