REIDER PART 2
92

352_Chaptf.r 9_Lumbar Spine

Figurę 9-20. Assessing L5 motor function. A, Extensor hallucis longus. B, Extensor digitorum longus. C, Gluteus medius.

stabilizes the patient s leg with one hand and asks the patient to rotate the foot outward. The examiner may have to passively place the patient s foot in eversion to communicatc the desired position. The patient is then instructed to maintain the foot in the evertcd position while the examiner attempts to invert the foot by pressing inward on the lateral aspect of the foot (sec Fig. 9-2IB). In the normal patient, the examiner is able to overcome the strength of the evertors only with difficulty.

The gluteus maximus is also supplied by the SI nerve root. To test it, the patient is asked to lic prone on the examination table and to flex the knee on the side being tested. The patient is then instructed to raise the thigh off the table. Finally, the examiner presses downward on the thigh with both hands while asking the patient to maintain the position of hip extension (see Fig. 9-21C). In a normal patient, the examincr experiences considerablc difficulty pushing the thigh back to the table.

52, 53, and 54 Newe Roots. The S2, S3, and S4 nerve roots may be compressed or injured by tumors or frac-tures of the sacrum, or, morę commonly, affected by spinał cord injury at a higher level. In the presence of spinał cord injury, the finding of sacral sparing, the prcscrvation of some function of the sacral nerve roots, is a positive factor in predicting the potential for recovery of function.

The S2, S3, and S4 nerve roots arc the principal nerve supply for the bladder, and they also supply the intrinsic muscles of the fect. Motor testing for these functions is dif-ficult. The motor function of the sacral nerve roots is, therefore, usually tested by performing a rectal examina-tion. When normal function is present, the examiner should notę fairly firm resistance as the examining finger enters the rcctum. The patient is then instructed to try to squcezc the examiner’s finger, thus contracting the external anal sphincter. This should produce a strong, readily pal-pable feeling of constriction around the examiners finger.

Reflex Examination

Deep tendon reflcxes are not easily assessed for all the lumbar and sacral nerve roots. Two principal deep tendon reflexes are normally tested: the patellar tendon reflex, which primarily involves the L4 nerve root, and the Achilles tendon reflex, which primarily involves the SI nerve root.