Biomaterial Database

The effects of inhibitory controls triggered by heterotopic noxious stimuli on a jaw reflex evoked by perioral stimuli in man. 1994

S W Cadden, and J P Newton

Department of Dental Prosthetics and Gerontology, Dental School, University of Dundee, U.K.

Electromyographic recordings (EMGs) were made from the active masseter muscle of the inhibitory reflex evoked by application of electrical stimuli to the skin of the upper lip in 11 human subjects. In control sequences, the reflex had a mean latency and duration of 41 +/- 1.7 and 44 +/- 2.6 ms, respectively. The magnitude of the reflex (measured by integration of the EMG) was significantly reduced by the application of cold (3 degrees C) or hot (47-48 degrees C) but not warm (38-46 degrees C) water to a hand or foot. The strongest stimuli (3 or 48 degrees C) produced mean reductions of the reflex magnitude in the range of 62-85%. These effects occurred regardless of whether the background activity in the masseter was raised or lowered during the application of the thermal stimuli. Thus, activity in nociceptive nerves from widespread areas of the body can modulate jaw reflexes in man by exerting an influence on the reflex pathway at a point before the motor neurones. This may involve the system of 'diffuse noxious inhibitory controls', which have been shown to depress limb flexion reflexes and neuronal activity in the spinal dorsal horn and trigeminal nuclear complex.

UI	MeSH Term	Description	Entries
D008046	Lip	Either of the two fleshy, full-blooded margins of the mouth.	Philtrum,Lips,Philtrums
D008297	Male		Males
D008406	Masseter Muscle	A masticatory muscle whose action is closing the jaws.	Masseter Muscles,Muscle, Masseter,Muscles, Masseter
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
D009619	Nociceptors	Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.	Pain Receptors,Receptors, Pain,Nociceptive Neurons,Neuron, Nociceptive,Neurons, Nociceptive,Nociceptive Neuron,Nociceptor,Pain Receptor
D010812	Physical Stimulation	Act of eliciting a response from a person or organism through physical contact.	Stimulation, Physical,Physical Stimulations,Stimulations, Physical
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
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D003213	Conditioning, Psychological	Simple form of learning involving the formation, strengthening, or weakening of an association between a stimulus and a response.	Conditioning, Psychology,Psychological Conditioning,Social Learning Theory,Social Learning Theories,Theory, Social Learning