What are the methods for examining tendon reflexes?
May 14, 2023
Source: Cainiu Health
Dr. Lin Yunfei
Introduction
The Achilles tendon reflex requires the knee joint to be flexed at approximately 90 degrees, with the foot dorsiflexed. Stabilize the top of the foot with one hand and strike the Achilles tendon with a rubber hammer, observing the degree and speed of foot dorsiflexion. For the elbow tendon reflex, tap the tendon above the elbow with a rubber hammer, which elicits a brief and rapid contraction of the biceps brachii muscle. The knee tendon reflex produces a quick and transient contraction of the quadriceps femoris muscle, resulting in extension of the knee.
Generally, tendon reflexes include three types: Achilles reflex, elbow tendon reflex, and knee tendon reflex, each assessed using a different method. The specific details are as follows:
1. Achilles Reflex
The patient sits or lies down with the knee bent at approximately 90 degrees and the foot dorsiflexed. The doctor stabilizes the top of the foot with one hand and uses a rubber hammer to tap the Achilles tendon. The degree and speed of plantar flexion of the foot are observed. Under normal conditions, the foot exhibits a rapid and brief plantar flexion response.
2. Elbow Tendon Reflex
The patient sits or lies down with the arm hanging naturally. The doctor uses a rubber hammer to strike the tendon above the elbow. Normally, this elicits a brief and rapid contraction of the biceps brachii muscle, resulting in flexion of the forearm.
3. Knee Tendon Reflex
The patient sits or lies down with the knee partially flexed. The doctor uses a rubber hammer to tap the patellar ligament just below the kneecap. Normally, this produces a quick and transient contraction of the quadriceps femoris muscle, leading to extension of the knee.
Tendon reflex testing primarily evaluates the presence, amplitude, symmetry, and duration of reflex responses. Normally, tendon reflexes are present, symmetric, and have relatively consistent amplitude and duration. If abnormalities are detected, they should be analyzed in conjunction with other clinical findings and test results to determine potential disorders of the neuromuscular system.
