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

A screen of lower 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 lower (and upper) extremity muscles is indicated to try to localize the patient’s pathology.

The upper motor neuron pathways that control the muscles of the lower extremities end primarily within the lumbar spinal cord, proceeding no further caudally than the first sacral level. The lower motor neurons that innervate the muscles of the legs leave the spinal cord primarily from the L1 through S1 levels. Table 26-1 summarizes the major innervation (root and nerve) of some of the most clinically relevant muscles of the lower extremities, as well as the functions of these muscles.

None.

Test and grade the muscles of the lower extremities according to the method described in Chapter 24, Approach to the Motor Examination. Figures 26-1, 26-2, 26-3, 26-4, 26-5, 26-6, 26-7, 26-8 and 26-9 illustrate and describe how to examine some of the major muscle groups of the lower extremities.