Muscle spindle supply to the bovine jaw muscles

Abstract

The jaw-closing muscles of two bovine fetuses average 1,177 muscle spindles on one side of the face: 549 in the masseter, 433 in the temporalis, 192 in the medial pterygoid, and three in the lateral pterygoid. The jaw-opening muscles have no spindles.

The neuropsychology of facial expression: A review of the neurological and psychological mechanisms for producing facial expressions.

“…The apparent lack of spindles in the muscles of expression is even more striking compared to their abundance in the muscles of mastication (supplied by the trigeminal nerve). The masseter and temporalis, for example, are among the muscles most richly supplied with spindles (Kubota, Komatsu, Nakamura, & Masegi, 1980;Lennartsson, 1980aLennartsson, , 1980bOlkowski & Manocha, 1973;Rozhold, 1980aRozhold, , 1980b. High spindle counts have also been found in the muscles of the tongue (Rozhold, 1980c), and moderate numbers have been documented in certain of the extraocular muscles-the muscles that move the eyes (Olkowski & Manocha, 1973).…”

Ultrastructural and biochemical changes of the medial pterygoid muscle induced by unilateral exodontia

“…The neuromuscular spindles are proprioceptors (Turker and Powers, 2001) that have the function to control mandibular movements (Kubota et al, 1980). In the masseter muscle, there are reports on degeneration of annulospiral endings in neuromuscular spindles due to soft diets in mice (Maeda et al, 1988), increase reflex in fusimotor activity during fatiguing muscle contraction (Ljubisavljevic and Anastasijevic, 1996), diameter reduction in both sides of intrafusal fibers by unilateral exodontia (Maeda et al, 1990) besides ultrastructural changes in neuromuscular spindles occurring through occlusal alterations (Santiwong et al, 2002;Bani and Bergamini, 2002).…”