Biomaterial Database

Patterns of jaw muscle activity during voluntary chewing. 1996

O Plesh, and B Bishop, and W D McCall

Department of Restorative Dentistry, University of California School of Dentistry, San Francisco, USA.

Mastication is controlled by central rhythm and burst generators, but whether this control is similar under automatic and voluntary chewing is not clear. Our first aim was to determine whether increased chewing frequency led to a proportional decrease in both the burst duration (the time of muscle activity) and the interburst interval (time of inactivity) of each muscle or to a minimal decrease in the burst duration and a substantial decrease in the interburst interval. Our second aim was to determine whether these two manifestations of control differed between the opening and closing muscles. Electromyograms from digastric, medial pterygoid, masseter and anterior temporalis muscles were obtained during gum chewing by five subjects at four frequencies. A nearly fourfold decrease in total cycle duration (TCD) with increased chewing frequencies was accompanied by minimal changes in burst duration in the digastric muscle but proportional changes in the jaw closing muscles. The onset latency of the digastric muscle as a percentage of TCD decreased and became negative (i.e. occurred before opening started) as the TCD decreased. The onset latencies of the jaw closing muscles remained roughly 10-20% of the TCD for the three lower chewing frequencies. Control of the opening muscle appears to differ from control of the closing muscles.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008406	Masseter Muscle	A masticatory muscle whose action is closing the jaws.	Masseter Muscles,Muscle, Masseter,Muscles, Masseter
D008409	Mastication	The act and process of chewing and grinding food in the mouth.	Chewing
D008410	Masticatory Muscles	Muscles arising in the zygomatic arch that close the jaw. Their nerve supply is masseteric from the mandibular division of the trigeminal nerve. (From Stedman, 25th ed)	Masticatory Muscle,Muscle, Masticatory,Muscles, Masticatory
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009334	Neck Muscles	The neck muscles consist of the platysma, splenius cervicis, sternocleidomastoid(eus), longus colli, the anterior, medius, and posterior scalenes, digastric(us), stylohyoid(eus), mylohyoid(eus), geniohyoid(eus), sternohyoid(eus), omohyoid(eus), sternothyroid(eus), and thyrohyoid(eus).	Muscle, Neck,Muscles, Neck,Neck Muscle
D009470	Muscle Spindles	Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.	Muscle Stretch Receptors,Neuromuscular Spindles,Receptors, Stretch, Muscle,Stretch Receptors, Muscle,Muscle Spindle,Muscle Stretch Receptor,Neuromuscular Spindle,Receptor, Muscle Stretch,Receptors, Muscle Stretch,Spindle, Muscle,Spindle, Neuromuscular,Spindles, Muscle,Spindles, Neuromuscular,Stretch Receptor, Muscle
D011626	Pterygoid Muscles	Two of the masticatory muscles: the internal, or medial, pterygoid muscle and external, or lateral, pterygoid muscle. Action of the former is closing the jaws and that of the latter is opening the jaws, protruding the mandible, and moving the mandible from side to side.	Muscle, Pterygoid,Muscles, Pterygoid,Pterygoid Muscle
D011930	Reaction Time	The time from the onset of a stimulus until a response is observed.	Response Latency,Response Speed,Response Time,Latency, Response,Reaction Times,Response Latencies,Response Times,Speed, Response,Speeds, Response