Figure 21-41 Technique for testing the triceps tendon reflex.
Figure 21-42 Another test of the triceps tendon reflex.
the elbow. This technique is demonstrated in Figure 21-41. This procedure is a test of the nerves at roots C6 to C8.
If the triceps tendon reflex cannot be elicited by this maneuver, try to hang the patient's arm over your arm, as demonstrated in Figure 21-42. Tapping the triceps tendon in this position often elicits the reflex.
Perform the patellar tendon reflex, also known as the knee jerk, by having the patient sit with his or her legs dangling off the side of the bed. Place your hand on the patient's quadriceps muscle. Strike the patellar tendon firmly with the base of the reflex hammer. A contraction of the quadriceps should be felt, and extension at the knee should be observed. This technique is demonstrated in Figure 21-43. It is a test of the nerves at roots L2 to L4.
The Achilles tendon reflex, also known as the ankle jerk, is elicited by having the patient sit with his or her feet dangling off the side of the bed. The leg should be flexed at the hip and the knee. The examiner places a hand under the patient's foot to dorsiflex the ankle. The Achilles tendon is struck just above its insertion on the posterior aspect of the calcaneus with the wide end of the reflex hammer. The result is plantar flexion at the ankle. This technique is demonstrated in Figure 21-44. It is a test of the nerves at roots S1 to S2.
Another method of testing for the Achilles reflex is to have the patient lie in bed. Flex one of the patient's legs at the hip and knee, and rotate the leg externally so that it lies on the opposite shin. Dorsiflex the ankle as the tendon is struck. This test is demonstrated in Figure 21-45A.
A patient with a depressed Achilles reflex should be asked to kneel, if possible, on the bed with the feet hanging off the side, as shown in Figure 21-45B. Tap the Achilles tendon, and observe the reflex response in this position.
The most commonly tested superficial reflexes are the abdominal and the cremasteric. The abdominal superficial reflex is elicited by having the patient lie on his or her back. An applicator stick or tongue blade is quickly stroked horizontally laterally to medially toward the umbilicus. The result is a contraction of the abdominal muscles, with the umbilicus deviating toward the stimulus. The abdominal reflex is frequently not seen in obese individuals. The cremasteric superficial reflex in men is elicited by lightly stroking the inner aspect of the thigh with an applicator stick or tongue depressor. The result is a rapid elevation of the testicle on the same side. Although the superficial reflexes are absent on the side of a corticospinal tract lesion, there is little clinical significance to their presence or absence. They are described here for completeness only.
Test for Abnormal Reflexes
Babinski's sign or reflex is a pathologic reflex. Normally, when the lateral aspect of the sole is stroked from the heel to the ball of the foot and curved medially across the heads of the metatarsal bones, there is plantar flexion of the big toe. This is a test of the nerve roots at L5 to S2. The foot should be stroked with a stimulus such as a key. A pin should never be used. In the presence of pyramidal tract disease, when the described movement is performed, there is dorsiflexion of the big toe, with fanning of the other toes. This is Babinski's reflex. Because Babinski's sign is an abnormal reflex, the clinician should note it only when it is present. It is correct to describe the plantar reflex as either plantar flexion (normal) or dorsiflexion (abnormal, Babinski's). The technique for evaluating the plantar reflex is shown in Figure 21-46.
Pyramidal tract disease is also suggested when the big toe dorsiflexes on stroking the lateral aspect of the foot. This is Chaddock's sign. In the presence of pyramidal tract disease, downward
Figure 21-46 A and B, Techniques for evaluating the plantar reflex.
pressure along the shin also causes the big toe to dorsiflex. This is Oppenheim's sign. The elicitation of these signs is less sensitive than stroking the plantar surface.
Another abnormal reflex associated with pyramidal tract disease is Hoffmann's sign. To elicit this sign, the patient's hand is pronated, and the examiner grasps the terminal phalanx of the middle finger between the index finger and thumb. With a sharp jerk, the phalanx is passively flexed and suddenly released. A positive response consists of adduction and flexion of the thumb as well as flexion of the other fingers.
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