Sample Thesis Paper
Jaw reflexes are of different kinds, including the jaw jerk reflex, the myotactic reflex, the jaw closing and opening (inhibitory) reflex. They occur in conjunction with the muscles of mastication, namely the masseter, temporalis, and the medial and lateral pterygoid. These are all bilaterally present in the mandible, and are all innervated by the trigeminal nerve (V3).
This paper will describe each reflex in turn, with the clinical relevance of the normal and abnormal reflexes along with published scientific research in dental journals that has focused on the mechanism of these reflexes. These reflexes, apart from signifying integrity of neuronal pathways and brainstem centers, also play a modulatory role during normal oral function. As such they may be abnormal in disorders of mastication associated with pain. (Maillou)
The jaw jerk is an abnormal response to a stimulus given to the area of the chin. It can be demonstrated in patients with damage to the area of the brain that coordinate motor activity of the trigeminal nerve (cranial nerve V). In these patients, this reflex can be elicited by keeping the mouth half open, steadying the chin with a finger, and hitting the finger on the chin at a downward angle with a rubber hammer. An abnormal response would be if the jaw deviates towards any side, or the jaw-jerk is very brisk. This would indicate lesions affecting the pyramidal pathways above the 5th nerve motor nucleus, especially if the lesions are bilateral. This is also called the chin reflex, chin-jerk reflex or the mandibular reflex. It is performed in people who have suspected damage to the trigeminal nerve and/or show signs of it.