Dictionary > Jaw jerk reflex

Jaw jerk reflex

Definition
noun
A stretch reflex that manifests as the contraction of the masseter and the temporalis muscles in response to the tapping of the lower jaw, and is used in neurological testing to determine the status of the trigeminal nerve
Supplement
A stretch reflex is a reflex reaction characterized by muscle contraction due to the stimulation of the muscle proprioceptors. When the muscle is stretched, the body reacts by resisting the stretch by reflex. Some of the stretch reflexes are jaw jerk reflex, biceps reflex, brachioradialis reflex, triceps reflex, patellar reflex, and ankle jerk reflex.
The jaw jerk reflex is a stretch reflex wherein the masseter and the temporalis muscles contract in response to the tapping of the lower jaw. This reflex is also used in neurological examinations to determine the status of the trigeminal nerve (cranial nerve V). The test is done by tapping at a downward angle the lower jaw through the chin just below the lips. The body responds by the masseter muscles jerking the lower jaw upwards. Under normal conditions, the individual would not demonstrate this reflex reaction. However, those with upper motor neuron lesions will have marked jaw jerk reflex reaction.
Synonyms:

  • masseter reflex

See also:

  • stretch reflex
  • trigeminal nerve


    You will also like...

    Flowers and tiny fruits of the pomegranate plant
    Fruits, Flowers, and Seeds

    This tutorial deals with the structure and function of flowers, fruits, and seeds. Also included here are the types of f..

    The process of photosynthesis
    Photosynthesis – Photolysis and Carbon Fixation

    Photosynthesis is the process that plants undertake to create organic materials from carbon dioxide and water, with the ..

    Gene Pool and Speciation
    The Gene Pool and Population Genetics

    According to Charles Darwin's theory of natural selection, preferable genes are favored by nature in the gene pool, and ..

    takahē
    Takahē (Porphyrio hochstetteri)

    Meet the colorful takahē, an extremely rare flightless bird. Find out more about its unique features and why they matte..

    Kidneys
    Kidneys and Regulation of Water and Inorganic Ions

    The kidneys are responsible for the regulation of water and inorganic ions. Read this tutorial to learn about the differ..

    Biological Energy
    ATP & ADP – Biological Energy

    ATP is the energy source that is typically used by an organism in its daily activities. The name is based on its structu..