A doctor looks for certain things during a physical examination depending on what disorder is suspected. When evaluating bones, if a fracture is suspected (see Fractures: Overview of Fractures), the doctor may notice that the affected part (such as an arm or a leg) is abnormally shaped, suggesting that the segments of bone are out of alignment. A doctor may palpate the surfaces of the bones to detect any tenderness or abnormal shape, particularly if a fracture, a tumor, or a bone infection (osteomyelitis) is suspected. Compression fractures of the spine due to osteoporosis may be very painful at first, but no abnormal shape may be evident. Abnormal bumps in bones occasionally indicate a tumor. If osteomyelitis is suspected, a doctor or nurse checks for a fever.

When a person complains of muscle weakness, the doctor checks muscles for bulk and texture and for tenderness. Muscles are also checked for twitches and involuntary movements, which may indicate a nerve disease rather than a muscle disease. Doctors look for wasting away of muscle (atrophy), which can result from damage to the muscle or its nerves or from lack of use (disuse atrophy), as sometimes occurs with prolonged bed rest. Doctors also look for muscle enlargement (hypertrophy), which normally occurs with an exercise such as weight lifting. However, when a person is ill, hypertrophy may result from one muscle working harder to compensate for the weakness of another. Muscles can also enlarge when normal muscle tissue is replaced by abnormal tissue (increasing the size but not the strength of the muscle), which occurs in amyloidosis and in certain inherited muscle disorders, such as Duchenne's muscular dystrophy.

Doctors try to establish which (if any) muscles are weak and how weak they are. The muscles can be tested systematically, usually beginning with the face and neck, then the arms, and finally the legs. Normally, a person should be able to hold the arms extended, palms up, for one minute without their sagging, turning, or shaking. Downward drift of the arm with palms turning inward is a sign of weakness. Strength is tested by pushing or pulling while the doctor pushes and pulls in the opposite direction. Strength is also tested by having the person perform certain maneuvers, such as walking on the heels and tiptoes or rising from a squatting position or getting up and down from a chair rapidly 10 times. The person is asked to look in all directions; if double vision develops, one or more eye muscles may be weak.

The doctor tests a joint's range of motion by moving the limb around a joint while the person is completely relaxed (passive movement). The doctor also checks muscle tone by testing passive movement. Resistance to such movement (passive resistance) may be decreased when the nerve leading to the muscle is damaged. Resistance to such movement may be increased when the spinal cord or brain is damaged. If a person is weak, doctors also tap the person's muscle tendon with a rubber hammer to check reflexes (see Symptoms and Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Reflexes). Reflexes may be slower than expected when the nerve leading to the muscle is damaged. Reflexes may be more rapid than expected when the spinal cord or brain is damaged.

Last full review/revision September 2006 by Michael Jacewicz, MD