The role of periodontal receptors in the jaw-opening reflex in the cat.

AUTOR(ES)

Dessem, D

RESUMO

1. In anaesthetized cats, graded electrical stimulation of the inferior alveolar nerve at just above threshold for the largest afferent fibres caused inhibition of jaw-closer motoneurones. Stimulus strength had to be increased to 1.5 times threshold with double shocks to cause reflex contraction of the digastric muscle. 2. Inhibition of jaw-closer muscles and excitation of digastric muscle resulted from transients of force applied to the upper canine tooth. However, the threshold for the digastric response was approximately 11 times higher than that of the periodontal afferent units recorded in the mesencephalic nucleus of the fifth nerve (MesV). Vibration of the upper canine at 50 Hz, with amplitude adequate to excite periodontal afferents, caused no digastric contraction. 3. Stimulation in the caudal part of the MesV so as to excite periodontal afferents caused no digastric reflex, provided that the stimulus did not spread to other parts of the fifth nerve nuclei. 4. It is concluded that under these conditions the low-threshold periodontal mechanoreceptors cause inhibition of jaw-closer muscles, but no significant excitation of jaw-opener muscles. 5. These findings are discussed from the point of view of the control which periodontal mechanoreceptors may exert over the biting force during mastication.

Documentos Relacionados

• Role of periodontal mechanoreceptors in evoking reflexes in the jaw-closing muscles of the cat.
• Muscle spindles in the jaw-closer muscles of the domestic cat.
• Branching of muscle spindle afferents of jaw closing muscles in the cat.
• A bladder-to-bladder cooling reflex in the cat.
• Lamina VIII interneurones interposed in crossed reflex pathways in the cat.