Examination of Upper Extremity Muscle Strength

PURPOSE

The purpose of the examination of upper extremity muscle strength is to localize neurologic pathology by looking for characteristic distributions of muscle weakness.

WHEN TO EXAMINE THE MUSCLE STRENGTH OF THE UPPER EXTREMITIES

A screen of upper extremity strength (see Chapter 40, Performing a Complete Neurologic Examination) should be performed on all patients as part of the routine neurologic examination. If weakness is suspected or found, a more detailed evaluation of upper (and lower) extremity muscles is indicated to try to localize the patient’s pathology.

NEUROANATOMY OF THE UPPER EXTREMITY MOTOR EXAMINATION

The upper motor neuron pathways that control the muscles of the upper extremities end primarily within the cervical spinal cord, proceeding no further caudally than the first thoracic level. The lower motor neurons that innervate the muscles of the arms leave the spinal cord primarily from the C5 through the T1 levels. Table 25-1 summarizes the major innervation (root and nerve) of some of the most clinically relevant muscles of the upper extremities, as well as the functions of these muscles.

EQUIPMENT NEEDED TO TEST UPPER EXTREMITY MUSCLE STRENGTH

None.

HOW TO EXAMINE THE MUSCLES OF THE UPPER EXTREMITIES

Test for Drift

Always start the examination of upper extremity strength by testing for drift:

Ask the patient to hold his or her arms straight in front of him or her with the palms up.
Instruct the patient to close his or her eyes.
Observe the arms for a few seconds while the patient’s eyes are closed.

Testing Upper Extremity Muscle Strength

Test and grade the muscles of the upper extremities according to the method described in Chapter 24, Approach to the Motor Examination. Figures 25-1, 25-2, 25-3, 25-4, 25-5, 25-6, 25-7, 25-8 and 25-9 illustrate and describe how to examine some of the major muscle groups of the upper extremities.

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