When a doctor tests your reflexes, she looks not only for movement of the stimulated muscle but also for speed and briskness of reaction. Slow or diminished reflexes can indicate a localized problem or a remote disease affecting neural function, likely near the spine. Abnormal reflex response ranges from absent or subtle, known as hyporeflexia, to overly brisk or repeating, known as hyperreflexia. With a partner, you can gauge your own reflex responses.
To test this reflex, lie belly down, or kneel on a chair, with your ankles extended beyond the bed or chair. The toes should point down, ankles facing the ceiling. Have a partner push your toes into flexion as he taps the achilles tendon with a hammer or sharply with a finger. In a normal reflex, the foot either kicks back or forward. The tester should then tap on either side of the tendon to gauge briskness of the reflex.
Many a schoolchild has tested the patellar reflex on her friends. Accurate placement of the percussion hammer is at the soft spot between the bottom of the knee cap and the top of the tibia. A healthy reflex looks like a kick and indicates proper functioning of the spinal cord, the nerves that run along it and the motor cortex of the brain. Diminished, subtle or absent reflex at the knee, known as the Erb-Westphal sign, could mean there is a problem near the vertebrae, such as a herniated disc or peripheral nerve disease.
The forearm reflex is known as the radial nerve reflex, or the extensor digitorum reflex, named after the muscle that runs from the elbow down the forearm to the wrist. Healthy reflex response is an indicator of normal neurologial function. A latent, or abnormal, reflex could indicate pathology of the radial nerve. To test this reflex, have a partner relax or partly flex their hands, then tap the thumb-side of forearm muscle a few inches above the wrist. In a healthy response, your partner's fingers will suddenly extend.
The biceps reflex tests function of the nerves of the upper arm and the C5 and C6 vertebrae of the cervical spine. To test it on a partner, have him sit with a relaxed arm. The arm should be slightly bent at the elbow. Find the place where the biceps muscle connects to the inner elbow. Using your thumb, place light pressure on the bicep and strike your own thumb with a reflex hammer. Proper functioning of the reflex causes a bicep curling motion that bends the elbow joint.
Is This an Emergency?
- NCBI; Deep Tendon Reflexes; H. Kenneth Walker; 1990
- YouTube; Achilles Reflex; September 2008
- "American Family Physician"; Clinical Evaluation and Treatment Options for Herniated Lumbar Disc; S. Craig Humphreys, M.D., and Jason C. Eck, M.S.; February 1999
- University of Cincinnati Clermont College: Biology Department; Spinal Reflex: The Patellar Reflex; David B. Fankhauser, Ph.D.; January 2009
- Biology Online; Westphal's Sign; 2011
- NCBI; Applying the extensor digitorum reflex to neurological examination; Zhang MJ, Zhu CZ, Duan ZM, Niu X.; October 2010
- The New York Times Health Guide; Radial Nerve Dysfunction; 2011
- YouTube; Lead Palsy Wrist Drop 1925; January 2011
- Loyola U.; Muscle Stretch Reflexes of the Upper & Lower Extremities; A. Chandrasekhar, MD; 2011