Muscle spindle supply in the pig masticatory muscles

This histological study was designed to define the anatomical background of the neuromuscular control mechanism involved in the non-ruminant omnivorous mastication, focusing on the muscle spindle supply to each muscle belly of the jaw muscles of 3 pig fetuses (near term). The jaw-closing muscle averaged 427 muscle spindles, 566 spindles, 703 spindles on one side of the face respectively: 160, 203, 240 in the temporalis, 122, 160, 248 in the masseter, 128, 154, 193 in the medial pterygoid, and 16, 49, 21 in the zygomaticomandibularis. No spindles were in the lateral pterygoid and the jaw-opening muscles.