Tibial Nerve: First Sacral Root, Gastrocnemius and Soleus Muscles There are several methods to elicit this reflex. Unfortunately, the most convenient and quickest are the least sensitive and least reliable.
• As in Figure 13-4A, with the patient supine and his legs extended at the knee, place the dorsum of your hand gently on the sole of the patient's foot and passively dorsiflex the foot. Then strike the palm of your hand with the hammer. You have used the foot as a lever to stretch the Achilles tendon and the gastrocnemius and soleus muscles. If there is no muscle contraction by this method, this does not mean that the reflex is absent; try the following method.
• As in Figure 13-4B (this is the conventional method), place one foot on the opposite shin, thereby flexing the knee. Apply gentle pressure to dorsi-flex the foot and then strike the tendon. If there is no response try the following. (Note: When the patient was prone and strength in the hamstrings and gluteus maximus muscles was being tested, there was an opportunity to examine the ankle reflex.)
• Flex the knee as in Figure 13-4C. Put gentle pressure on the sole of the foot to evoke some dorsiflexion and muscle stretching, then strike the tendon. If the reflex is absent by this method, there is disease in the segmental arc.
• Having the patient kneel on the edge of the examining table with his back to you is about as reliable as the previous method. As in Figure 13-4D, passively dorsiflex the foot before you strike the tendon.
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