About Video

The jaw jerk or masseter reflex is a stretch reflex to assess the integrity of the trigeminal nerve. Normally, it is absent or minimal but can be of diagnostic value in upper motor neurons lesions above the cervical level. It is a monosynaptic reflex subserved by the sensory and motor components of the trigeminal nerve, the nucleus being the trigeminal mesencephalic nucleus in the pons. An exaggerated reflex is indicative of pseudobulbar palsy of any etiology. The reflex is of higher amplitude in the female sex and the latency increases with age.