Temporomandibular Joint Capsule Research Articles

Neurophysiological Studies on the Mechanisms of the Jaw Tongue Reflex in the Cat

Tongue was reflexly retracted by passive depression of the mandible in adecerebrate cat. The purpose of this study is to clarify the mechanisms of this “Jaw-Tongue Reflex”. Electromyographic activities of jaw closing muscles and of extrinsic tongue muscles were recorded during this reflex. Results obtained were as follows.1) The styloglossal and the genioglossal muscles were activated by passive depression of the mandible, while the hyoglossal muscle was not.2) These tongue muscle activities were elicited when the mouth was opened beyond 10deg;, while activities of the masticatory muscle were induced by only 2deg; of opening.3) The Jaw-tongue reflex was not affected by neither masseter nerve sectioning noranesthetization of the temporomandibular joint capsule.4) Exfoliation of the temporal muscle from the attachment to the temporal bone greatly reduced tongue muscle activities at the jaw-tongue reflex. Extension of the temporal muscle induced by downward stretch of the isolated coronoid process of the mandible elicited the tongue muscle activities.5) Repetitive electrical stimulation (100Hz, 0.1msec) of the temporal nerve activated tongue muscle activities, and the threshold of this activation was between 1.3 and 1.7 times threshold of the temporal nerve.6) Vibratory stimuli applied to the mandible at a frequency of less than 130Hz were also effective in evoking the jaw-tongue reflex, and most effective frequency of stimulationwas 70Hz. However, vibratory frequency more than 130Hz was ineffective and tongue muscle was not activated at all. In contrast, jaw closing muscle was followed to such high frequency vibratory stimuli and activated through tonic vibration reflex.7) Time course of adaptation to sustained mouth opening was different between tongue muscle activities and those of masticatory muscle. The former sustained their activities longer than the latter.8) The Jaw-tongue reflex was diminished by rostrocaudal section between the mesencephalic trigeminal nucleus and the motor trigeminal nucleus.These results indicate that receptors of the Jaw-tongue reflex are mainly located in the tempo

Trigeminal nerve and temporomandibular joint of the cat: A horseradish peroxidase study

The mesencephalic nucleus of the trigeminal nerve is considered to contain the cell bodies of the first-order neurons that have peripheral connections in the temporomandibular joint capsule. Through use of retrograde transport of horseradish peroxidase, this concept is challenged. The results indicate that a relatively specific region of the mandibular division of the trigeminal ganglion of the cat contains the first-order neurons innervating the temporomandibular joint capsule.

Reflex activation of extrinsic tongue muscles by jaw closing muscle proprioceptors.

Depression of the mandible in the decerebrate cat induced retraction of the tongue. The mechanism of this jaw-tongue reflex was analyzed by recording electromyographic activity from the temporal and styloglossal muscles as representative masticatory and extrinsic tongue muscles, respectively. Tongue muscle activity was elicited when the mouth was opened beyond 10 degrees while the threshold for the masticatory muscle activities was around 2 degrees. Neither sectioning of the masseteric nerve nor anesthetization of the temporomandibular joint capsule affected the tongue muscle activities. In contrast, exfoliation of the temporal muscle from the temporal bone greatly reduced the effects of jaw depression. When the isolated coronoid process of the mandible was stretched downwards, activities were evoked in the tongue muscle. Repetitive electrical stimulation at a frequency of 100 Hz to the temporal nerve activated the tongue muscle, and the threshold of reflex activation was between 1.3 and 1.7 times threshold of the temporal nerve. Vibratory stimuli applied to the mandible at frequencies below 130 Hz were also effective in evoking tongue muscle activity. However, when the frequency was above 135Hz, tongue muscle activity was not induced although activity was still observed in the masticatory muscles. These results indicate that the jaw-tongue reflex is elicited mainly by proprioceptors in the temporal muscle, and that they may probably be the Golgi tendon organs and the secondary endings rather than the primary endings of the muscle spindle.

Clinical kinesthetic experiments on the lateral pterygoid muscle and temporomandibular joint in man.

The possible kinesthetic function of proprioceptors in the lateral pterygoid muscle was clinically assessed after anesthesia of muscle and temporomandibular joint receptors, respectively. A mandibular posture was actively and repetitively produced with an average accuracy of 2.5 mm, while the accuracy decreased by about two-fold after narcotization. It is suggested that muscle spindles in the lateral pterygoid muscle as well as mechanoreceptors in the temporomandibular joint capsule are active in the perception and/or control of mandibular postures.

A study on inhibition of masseteric α-motor fibre discharges by mechanical stimulation of the temporomandibular joint in the cat

The role of afferent inputs from the temporomandibular joint (TMJ) in controlling the masseter muscle activity was studied in cats. Mechanical stimulation (pressure application to the capsule and rotatory movement of the isolated condyle to the opening direction) of the TMJ capsule produced inhibitory effects on the masseteric α-motor fibre discharges.

Afferent discharges from temporomandibular articular mechanoreceptors: An experimental analysis of their behavioural characteristics in the cat

The stimulus-response characteristics of the mechanoreceptors in the anterior, lateral and posterior regions of the capsule of the temporomandibular joint of the cat were examined electrophysiologically during graduated passive movements of isolated joints. Analysis of the resulting afferent potential discharges in the articular nerves confirmed the presence in the joint capsule of two varieties of mechanoreceptor differing in latency, threshold and adaptation time. It is suggested that these two functional varieties of articular mechanoreceptor response correlate with the two morphological varieties of corpuscular endorgan (Type I and Type II) previously demonstrated histologically in the temporomandibular joint capsule. Type I mechanoreceptor clusters had a latency range (from the onset of jaw movement) of 0.8 sec to more than 3.0 sec, and an adaptation time of up to 20 sec. The lowest threshold receptors were activated by the capsular tension prevailing when the jaw was kept closed, whilst higher threshold receptors were activated sequentially as appropriate jaw movements caused a progressive increase in local capsular tension. Type II mechanoreceptors uniformly had very short latencies, and an adaptation time of only 0.2–1.0 sec. These receptors were activated at the onset of jaw movements only, then being stimulated en masse due to their relatively uniform threshold. It would appear that the major articular contribution to the reflex regulation of motor unit activity in the mandibular musculature is provided by the Type I mechanoreceptors. These contribute to reflex regulation of postural muscle tone, to coordinated muscle activity (reinforced by the Type II mechanoreceptors) during jaw movement, and to perceptual awareness of jaw position.

Positions and movements of mandible and hyoid bone during swallowing. A cineradiographic study of swallowing with and without anaesthesia of the temporomandibular joints.

The positions and movements of the mandible and the hyoid bone during swallowing with and without anaesthesia of the temporomandibular joint capsules were studied cineradio-graphically in 11 female subjects aged 19-31 years. Swallowing with contact between the teeth was found to be more common than swallowing without contact. The contact was established most often in the intercuspal position but contact occurred also anteriorly and posteriorly to the intercuspal position and in the retruded position of the mandible. No difference was found in the occurrence or localisation of the contact between the teeth on comparison between swallowing before and during the anaesthesia.The pattern of movements of the hyoid bone were found to be regular in some persons with an even circular or elliptic path of movement during the act of swallowing, while in others the path was more irregular, sometimes with crossing pathways. The pattern of movement did not vary with the medium swallowed (saliva, watery barium and viscou...

Afferent discharges from temporomandibular articular mechanoreceptors: An experimental study in the cat

The stimulus-response characteristics of the mechanoreceptors in the posterior capsule of the temporomandibular joint of the cat were examined oscilloscopically during graduated passive movements of isolated joints. Analysis of the resulting afferent action-potential discharges in articular nerves confirmed the presence in the joint capsule of two varieties of mechanoreceptor differing in latency, threshold and adaptation time. The two functional varieties of articular mechanoreceptor response correlated with the two (Type I and Type II) morphological varieties of corpuscular end-organ previously demonstrated histologically in the temporomandibular joint capsule. A rapidly adapting discharge, attributed to the Type II receptors, was evoked only at the onset of joint movement, and then produced transient reflex facilitation of motor units in the prime movers of the joint. A slowly adapting discharge, attributed to the Type I receptors whose graded thresholds provided a continuing (though fluctuating) discharge throughout all joint movements, contributed co-ordinated facilitatory and inhibitory reflex influences to motoneurones innervating the mandibular musculature, as well as contributing to mandibular kinaesthesis.

On the nerve distribution of the temporomandibular joint capsule

On the nerve distribution of the temporomandibular joint capsule