"Influence of age and gender on the jaw-stretch and blink reflexes". ^ Peddireddy, Anitha Wang, Kelun Svensson, Peter Arendt-Nielsen, Lars ()."The influence of gender on the masseter electromyographic jaw-jerk reflex in young human subjects". Archived from the original on 7 October 2016. Sinauer Associates: Massachusetts 2002, p. 484. But several textbooks of neurology and clinical neurophysiology attribute discovery of the jaw jerk reflex to Armand de Watteville (1846–1925) as he correctly predicted that the jaw jerk would be valuable to detect disease affecting bulbar nuclei. History Īmerican neurologist Morris Lewis (1852–1928) first described the jaw jerk. In other words, a normal jaw jerk reflex points the diagnosis toward cervical spondylotic myelopathy and away from MS or ALS. The clinical presentation of cervical spondylotic myelopathy can be similar to multiple sclerosis (MS) or amyotrophic lateral sclerosis (ALS), however, a hyperactive jaw reflex suggests the pathology is above the foramen magnum. This motion delays the decrease in lean body mass and aids protein retention that comes with age, preventing the muscular tissues from wearing and tearing. Jaw muscles do not display very prominent changes in muscular tissue with age in healthy elderly, as their oral cavities are in constant motor movement (i.e.: performing tasks such as talking and chewing etc.). A study also reports that 52% of the elderly exhibit an absence of jaw jerk reflex, in an average age of 81.8 years. The most prominent decline in masseteric activity was recorded in patients aged 75 years and older, which might be due to the reduction in both tendon and superficial reflexes. Latency is defined here as the time taken between the chin tap to the first obvious deflection as seen on the subject. Studies have shown that there has been a slight general increase in latency of this reflex with increasing age. This variation in women appears to be constant, and is not affected by the menstrual cycle. The mean latency of the impulse was also found to be shorter in females than in males. This should be taken into account when interpreting ECM results, as a female's graphs will normally show a higher peak to peak amplitude than a male. Females showed a significantly higher amplitude – meaning that the impulse was larger – than males. The ECMs were focussed on the masseter muscle and temporalis muscle. Electromyographs are used to measure the impulse within the muscle, allowing the amplitude of the impulse to be known and shown on a graph. Studies have shown that there is a significant effect of gender on the jaw jerk reflex. It is performed when there are other signs of damage to the trigeminal nerve.įactors affecting the reflex Gender It is not part of a standard neurological examination. Both the sensory and motor aspects of this reflex are through CN V. This reflex is used to judge the integrity of the upper motor neurons projecting to the trigeminal motor nucleus. As with most other reflexes, the response to the stimulus is monosynaptic, with sensory neurons of the trigeminal mesencephalic nucleus sending axons to the trigeminal motor nucleus, which in turn innervates the masseter. The jaw jerk reflex can be classified as a dynamic stretch reflex. However, in individuals with upper motor neuron lesions the jaw jerk reflex can be quite pronounced. Normally this reflex is absent or very slight. In response, the masseter muscles will jerk the mandible upwards.
The mandible-or lower jaw-is tapped at a downward angle just below the lips at the chin while the mouth is held slightly open.
The jaw jerk reflex or the masseter reflex is a stretch reflex used to test the status of a patient's trigeminal nerve ( cranial nerve V) and to help distinguish an upper cervical cord compression from lesions that are above the foramen magnum.
0 kommentar(er)
