Jaw-opening reflex activity in the inferior head of the lateral pterygoid muscle in man.

Jaw-opening reflex excitation and inhibition in this muscle and the anterior digastric were only observed during activation and not when the muscles were relaxed. After electrical stimulation of the palate over the greater palatine nerve, reflex excitation of the lateral pterygoid was observed in all subjects with average latency 19.4 ms. Excitation in the anterior digastric muscle was found in only five of the eight subjects with latency 18.6 ms. Excitation of the jaw-opening muscles occurred during the inhibition of the jaw-closing muscles, and conversely, jaw-closing muscle excitation occurred during a silencing of the jaw-opening muscles. This suggests a central control over the facilitation and inhibition of jaw-opening and jaw-closing muscle activity.