Patellar Reflex Arc Diagram
Knee-jerk reflex , also called patellar reflex , sudden kicking movement of the lower leg in response to a sharp tap on the patellar tendon, which lies just below the kneecap. One of the several positions that a subject may take for the test is to sit with knees bent and with one leg crossed over the other so that the upper foot hangs clear of the floor. The sharp tap on the tendon slightly stretches the quadriceps, the complex of muscles at the front of the upper leg. In reaction these muscles contract, and the contraction tends to straighten the leg in a kicking motion. Exaggeration or absence of the reaction suggests that there may be damage to the central nervous system. The knee jerk can also be helpful in recognizing thyroid disease. We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind. Your contribution may be further edited by our staff, and its publication is subject to our final approval. Unfortunately, our editorial approach may not be able to accommodate all contributions. Our editors will review what you’ve submitted, and if it meets our criteria, we’ll add it to the article. Please note that our editors may make some formatting changes or correct spelling or grammatical errors, and may also contact you if any clarifications are needed. Knee-jerk reflex medical test. The Editors of Encyclopaedia Britannica. Learn More in these related Britannica articles: The familiar knee-jerk reflex, tested routinely by physicians, is a spinal reflex in which a brief, rapid tap on the knee excites muscle spindle afferent neurons, which then excite the motor neurons of the stretched muscle via a single synapse in the spinal cord. The knee jerk, or patellar reflex, that follows a tap just below the kneecap of a freely hanging leg is one such involuntary reflex. Sensory afferent impulses from stretching the receptors e. More About Knee-jerk reflex 3 references found in Britannica articles Assorted References kinesthetic sense In human sensory reception: Nerve function muscle spindle action In mechanoreception: Muscle spindles In human nervous system: Help us improve this article! Contact our editors with your feedback. You may find it helpful to search within the site to see how similar or related subjects are covered. Any text you add should be original, not copied from other sources. At the bottom of the article, feel free to list any sources that support your changes, so that we can fully understand their context. Internet URLs are the best. Thank You for Your Contribution! There was a problem with your submission. Please try again later. Keep Exploring Britannica Atom. Atom, smallest unit into which matter can be divided without the release of electrically charged particles. Quantum mechanics, science dealing with the behaviour of matter and light on the atomic and subatomic…. Photosynthesis, the process by which green plants and certain other organisms transform light energy…. View All Media 1 Image. If you prefer to suggest your own revision of the article, you can go to edit mode requires login. Thank you for your feedback. Facts matter and Britannica Insights makes it easier to find them.
A common example of a reflex action is the patellar reflex (‘knee jerk’ response) Drawing and labelling a diagram of a reflex arc for a pain withdrawal reflex.
The Reflex Arc. How a Stimulus Elicits a Response.
Page 2. A Knee-Jerk Response The knee-jerk reflex is base on the hammer changing the shape of a . pathways are called reflex arcs.
2-Minute Neuroscience: Knee-jerk Reflex
Diagram of a chemical synapse between The reflex arc of the patellar or “knee jerk” reflex. 1) Tapping on the patellar.
The reflex arc governs the operation of reflexes. Nerve impulses Reflexes whose arc pass through the Tapping the patellar tendon stretches the quadriceps.
Nervous system 3, Reflex arc.
Alternative Title: patellar reflex Knee-jerk reflex, also called patellar reflex, sudden kicking movement of the lower leg in response to a muscle spindle action.Monosynaptic Reflex. The simplest reflex arc: the monosynaptic (stretch) reflex.
REFLEX ACTION(Reflex arc,structure and function explained)
On entering the spinal cord the sensory axons often divide to form axon wiringall.com all axons distribute their information to multiple groups of post-synaptic wiringall.com post-synaptic cells may be . Introduction to reflex arc diagram. Reflex action is a spontaneous rapid and predictable motor response to a stimulus which will be repeated in a similar fashion each time the stimulus is presented.
When a reflex arc in an animal consists of only one sensory neuron and one motor neuron, it is defined as monosynaptic, referring to the presence of a single chemical wiringall.com the case of peripheral muscle reflexes (patellar reflex, achilles reflex), brief stimulation to the muscle spindle results in contraction of the agonist or effector wiringall.com contrast, in polysynaptic reflex pathways.
Draw a diagram and label the parts of the cross section of a spinal cord. Draw a diagram identifying the different components of a reflex arc.
Be sure to label the direction of the reflex and beside each component, briefly describe its role in the function of the reflex. In-Lab Activity: Observe the model of the cross section of the spinal cord.
The reflex arc governs the operation of reflexes. Nerve impulses follow nerve pathways as they travel through the nervous system.
The simplest of these pathways, including a few neurons.Reflex Arcs | BioNinjaPatellar reflex – Wikipedia