Peripheral nerves and reflexes
Content:
- Testing of reflexes
- Deep reflexes
- Surface reflections
- Infants
- Low back pain
Testing of reflexes
A reflex is a simple nerve circuit. A stimulus, such as a light tap with a rubber hammer, causes sensory neurons (nerve cells) to send signals to the spinal cord. There, the signals are conveyed both to the brain and to nerves that control muscles affected by the stimulus. Without any brain intervention, these muscles may respond to an appropriate stimulus by contracting.
Reflex tests measure the presence and strength of a number of reflexes. In so doing, they help to assess the integrity of the nerve circuits involved. Reflex tests are performed as part of a neurological exam, either a "mini-exam" done to quickly confirm integrity of the spinal cord, or a more complete exam performed to diagnose the presence and location of a spinal cord injury or neuromuscular disease.
Deep tendon reflexes are responses to muscle stretch. The familiar "knee-jerk" reflex is an example of a reflex. This tests the integrity of the spinal cord in the lower back region. The usual set of deep tendon reflexes tested, involving increasingly higher regions of the spinal cord, includes:
ankle
knee
abdomen
forearm
biceps
triceps
patellar
Another type of reflex test is called the Babinski test, which involves gently stroking the sole of the foot to assess proper development and function of the spine and cerebral cortex.
Precautions
Reflex tests are entirely safe, and no special precautions are needed.
Description
The examiner uses a reflex hammer or rubber mallet to strike different points on the examinee's body, and observes the response. The points chosen for eliciting reflexes are the tendons of specific muscles. Tapping specific sites is intended to provide a quick stretch to the muscle. Muscle spindles, or receptors, mediate the reflex lying within the muscleot the site of the hammer strike. The examiner may position, or hold, one of the limbs during testing, and may require exposure of the ankles, knees, abdomen, and arms. Reflexes can be difficult to elicit if the individual being examined is paying too much attention to the stimulus. To compensate for this, that person may be asked to perform some muscle contraction, such as clenching teeth or grasping and pulling the two hands apart.
Babinski reflex test, the examiner will gently stroke the outer soles of the person's feet with the mallet while checking to see whether or not the big toe extends out as a result.
Preparation
The examiner positions the person to be examined in a comfortable position, usually seated on the examination table with legs hanging free. There is no other preparation.
Aftercare
A reflex examination is not invasive. No care after the examination is required.
Reflex tests measure the presence and strength of a number of reflexes. In so doing, they help to assess the integrity of the nerve circuits involved. Reflex tests are performed as part of a neurological exam, either a "mini-exam" done to quickly confirm integrity of the spinal cord, or a more complete exam performed to diagnose the presence and location of a spinal cord injury or neuromuscular disease.
Deep tendon reflexes are responses to muscle stretch. The familiar "knee-jerk" reflex is an example of a reflex. This tests the integrity of the spinal cord in the lower back region. The usual set of deep tendon reflexes tested, involving increasingly higher regions of the spinal cord, includes:
ankle
knee
abdomen
forearm
biceps
triceps
patellar
Another type of reflex test is called the Babinski test, which involves gently stroking the sole of the foot to assess proper development and function of the spine and cerebral cortex.
Precautions
Reflex tests are entirely safe, and no special precautions are needed.
Description
The examiner uses a reflex hammer or rubber mallet to strike different points on the examinee's body, and observes the response. The points chosen for eliciting reflexes are the tendons of specific muscles. Tapping specific sites is intended to provide a quick stretch to the muscle. Muscle spindles, or receptors, mediate the reflex lying within the muscleot the site of the hammer strike. The examiner may position, or hold, one of the limbs during testing, and may require exposure of the ankles, knees, abdomen, and arms. Reflexes can be difficult to elicit if the individual being examined is paying too much attention to the stimulus. To compensate for this, that person may be asked to perform some muscle contraction, such as clenching teeth or grasping and pulling the two hands apart.
Babinski reflex test, the examiner will gently stroke the outer soles of the person's feet with the mallet while checking to see whether or not the big toe extends out as a result.
Preparation
The examiner positions the person to be examined in a comfortable position, usually seated on the examination table with legs hanging free. There is no other preparation.
Aftercare
A reflex examination is not invasive. No care after the examination is required.
Deep reflexes
Although one generally finds it easy to elicit the reflexes after one has acquired some experiences it is necessary to make sure that the patient relaxes his limbs and that his attention is distracted from the tests. One should strike the tendon and not the muscle, because in the latter case one tests myotatic irritability and not the tendon reflex. For the deep reflexes it is well to place the limb or muscle in the half way position between contraction and relaxation. Where the reflex is difficult to obtain, reinforcement (shunting of inhibition) is used. This is accomplished by having the patient to innervate actively a corresponding muscle, tightly grip his own hands or another object on a given command and striking the tendon at the same instant. Sometimes the reflex contraction is not seen, but can be felt. Occasionally upper motor neuron (pyramidal tract) disease is accompanied by hyperactive deep reflexes which cannot be elicited because the limb is too spastic and held rigid either in flexion or extension. A percussion hammer is used for obtaining the deep reflexes and a pinwheel a dull pin or toothpick for the superficial.
The patient opens his mouth so that the lower jaw hangs a little. A wooden tongue depressor is placed on the molars and struck a sharp blow. Result: Palpable or visible contraction of the masseter and rising of the jaw itself. Another way of eliciting the reflex is by placing the finger or thumb on the side of the lower jaw and striking it with the hammer. The jaw is mediated through the trigeminal nerve, and the reflex center is in the Pons.
The pectoral reflexes. The arm is placed halfway between adduction and abduction and the finger on the muscle tendon near the humerus.
The patient opens his mouth so that the lower jaw hangs a little. A wooden tongue depressor is placed on the molars and struck a sharp blow. Result: Palpable or visible contraction of the masseter and rising of the jaw itself. Another way of eliciting the reflex is by placing the finger or thumb on the side of the lower jaw and striking it with the hammer. The jaw is mediated through the trigeminal nerve, and the reflex center is in the Pons.
The pectoral reflexes. The arm is placed halfway between adduction and abduction and the finger on the muscle tendon near the humerus.
Surface reflections
Test for touch. Touch the skin with a cotton ball using light strokes. Do not press down on the skin or touch areas of the skin that have hair. Instruct the patient to point to the area you have touched or tell you when he feels the sensation of being touched. (Obviously, he will not be watching you touch his skin).
Reflexes. A reflex may be defined as an immediate and involuntary
response to a stimulus. A reflex is a fast response to a change in the body's internal or external environment in an attempt to restore homeostasis.
Reflexes and diagnosis. Evaluation of a reflex can aid a doctor in diagnosing a problem. A reflex which stops functioning or functions abnormally may indicate that a particular conduction pathway in the body has been damaged. Testing internal organs for reflex is not practical for diagnosis, but somatic reflexes (reflexes
resulting in the contraction of skeletal muscles) are excellent diagnostic tools.
Superficial reflexes. Stroke the skin with a hard object such as an applicator stick. What is felt is a superficial reflex.
Muscle reflexes. Muscle reflexes help determine how responsive the spinal cord is. If many impulses are transmitted from the brain to the spinal cord, the muscle reflexes become so sensitive that just tapping the tendon of the knee with the tip of your finger can cause the leg to jump a considerable distance. If, however, the cord is overwhelmed by other impulses from the brain, it may be impossible to cause the muscles or tendons to respond.
Reflexes. A reflex may be defined as an immediate and involuntary
response to a stimulus. A reflex is a fast response to a change in the body's internal or external environment in an attempt to restore homeostasis.
Reflexes and diagnosis. Evaluation of a reflex can aid a doctor in diagnosing a problem. A reflex which stops functioning or functions abnormally may indicate that a particular conduction pathway in the body has been damaged. Testing internal organs for reflex is not practical for diagnosis, but somatic reflexes (reflexes
resulting in the contraction of skeletal muscles) are excellent diagnostic tools.
Superficial reflexes. Stroke the skin with a hard object such as an applicator stick. What is felt is a superficial reflex.
Muscle reflexes. Muscle reflexes help determine how responsive the spinal cord is. If many impulses are transmitted from the brain to the spinal cord, the muscle reflexes become so sensitive that just tapping the tendon of the knee with the tip of your finger can cause the leg to jump a considerable distance. If, however, the cord is overwhelmed by other impulses from the brain, it may be impossible to cause the muscles or tendons to respond.
Low back pain
Low back pain or lumbago (play /lʌmˈbeɪɡoʊ/) is a common musculoskeletal disorder affecting 80% of people at some point in their lives. In the United States it is the most common cause of job-related disability, a leading contributor to missed work, and the second most common neurological ailment — only headache is more common. It can be either acute, subacute or chronic in duration. With conservative measures, the symptoms of low back pain typically show significant improvement within a few weeks from onset.
The lumbar region (or lower back region) is made up of five vertebrae (L1-L5). In between these vertebrae lie fibrocartilage discs (intervertebral discs), which act as cushions, preventing the vertebrae from rubbing together while at the same time protecting the spinal cord. Nerves stem from the spinal cord through foramina within the vertebrae, providing muscles with sensations and motor associated messages. Stability of the spine is provided through ligaments and muscles of the back, lower back and abdomen. Small joints which prevent, as well as direct, motion of the spine are called facet joints (zygapophysial joints).
Causes of lower back pain are varied. Most cases are believed to be due to a sprain or strain in the muscles and soft tissues of the back. Overactivity of the muscles of the back can lead to an injured or torn ligament in the back which in turn leads to pain. An injury can also occur to one of the intervertebral discs (disc tear, disc herniation). Due to aging, discs begin to diminish and shrink in size, resulting in vertebrae and facet joints rubbing against one another. Ligament and joint functionality also diminishes as one ages, leading to spondylolisthesis, which causes the vertebrae to move much more than they should. Pain is also generated through lumbar spinal stenosis, sciatica and scoliosis. At the lowest end of the spine, some patients may have tailbone pain (also called coccyx pain or coccydynia). Others may have pain from their sacroiliac joint, where the spinal column attaches to the pelvis, called sacroiliac joint dysfunction which may be responsible for 22.6% of low back pain. Physical causes may include osteoarthritis, rheumatoid arthritis, degeneration of the discs between the vertebrae or a spinal disc herniation, a vertebral fracture (such as from osteoporosis), or rarely, an infection or tumor.
In the vast majority of cases, no noteworthy or serious cause is ever identified. If the pain resolves after a few weeks, intensive testing is not indicated.
Causes of lower back pain are varied. Most cases are believed to be due to a sprain or strain in the muscles and soft tissues of the back. Overactivity of the muscles of the back can lead to an injured or torn ligament in the back which in turn leads to pain. An injury can also occur to one of the intervertebral discs (disc tear, disc herniation). Due to aging, discs begin to diminish and shrink in size, resulting in vertebrae and facet joints rubbing against one another. Ligament and joint functionality also diminishes as one ages, leading to spondylolisthesis, which causes the vertebrae to move much more than they should. Pain is also generated through lumbar spinal stenosis, sciatica and scoliosis. At the lowest end of the spine, some patients may have tailbone pain (also called coccyx pain or coccydynia). Others may have pain from their sacroiliac joint, where the spinal column attaches to the pelvis, called sacroiliac joint dysfunction which may be responsible for 22.6% of low back pain. Physical causes may include osteoarthritis, rheumatoid arthritis, degeneration of the discs between the vertebrae or a spinal disc herniation, a vertebral fracture (such as from osteoporosis), or rarely, an infection or tumor.
In the vast majority of cases, no noteworthy or serious cause is ever identified. If the pain resolves after a few weeks, intensive testing is not indicated.
