tonic reflex

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ton·ic re·flex

the occurrence of an appreciable interval after the production of a reflex before relaxation, for example, the leg remains up for a time after a knee jerk.
Synonym(s): Gordon symptom


Alfred, U.S. neurologist, 1874-1953.
Gordon reflex - dorsal flexion of the great toe produced by firm lateral pressure on the calf muscles. Synonym(s): paradoxical flexor reflex
Gordon sign - a sign of organic hemiplegia. Synonym(s): finger phenomenon
Gordon symptom - the occurrence of an appreciable interval after the production of a reflex before relaxation. Synonym(s): tonic reflex


a reflected involuntary action or movement; the sum total of any particular automatic response mediated by the nervous system.
A reflex is built into the nervous system and does not need the intervention of conscious thought to take effect.
For reflexes used in clinical examination of a patient see under individual titles including anal, blink, corneal, conjunctival, crossed extensor, extensor thrust, eyelid, gastrocnemius, hopping, palpebral, panniculus, patellar, perineal, placing, pupillary, withdrawal.

accommodation reflex
the coordinated changes that occur when the eye adapts itself for near vision; they are constriction of the pupil, convergence of the eyes and increased convexity of the lens.
reflex action
an involuntary response to a stimulus conveyed to the nervous system and reflected to the periphery (see also reflex).
reflex bradycardia
bradycardia occurring as a reflex initiated by severe atrial or ventricular stretch.
chain reflex
a series of reflexes, each serving as a stimulus to the next, making a complete activity.
complete reflex
one requiring no feedback from the forebrain.
conditioned reflex
see conditioned response.
cutaneous trunci reflex
see panniculus reflex.
dazzle reflex
a test of the retina, optic nerve, and central retinal pathways. Shining a bright light into the eye should cause squinting.
reflex dyssynergia
see detrusor-urethral dyssynergia.
gastroileal reflex
increase in ileal motility and opening of the ileocecal valve when food enters the empty stomach.
light reflex
see pupillary light reflex.
nociceptive reflex
reflexes initiated by painful stimuli.
palatal reflex
see swallowing reflex.
rectosphincteric reflex
relaxation of the anal sphincter which occurs with distention of the rectum and during defecation.
stepping reflex
movements of progression elicited when the animal is held upright and inclined forward with the feet touching a flat surface.
stretch reflex
reflex contraction of a muscle in response to passive longitudinal stretching.
superficial reflex
any withdrawal reflex elicited by noxious or tactile stimulation of the skin, cornea or mucous membrane, including the corneal and pharyngeal reflexes.
tapetal reflex
tapetal reflection of light.
tendon reflex
a method of testing the patency of reflex arc. The tendon is stretched sharply by tapping it close to its insertion. A positive reaction is a sharp contraction of the muscle of which the tendon is part. The patellar reflex is the best known of these reflexes. Absence indicates a defect in the reflex arc, an exaggerated response suggests an upper motor neuron lesion. Called also myotactic reflex.
tonic reflex
see tonic neck response.
triceps surae reflex
Achilles reflex.
trigemino-abducens reflex
a test of the ophthalmic and mandibular divisions of the trigeminal nerve, and the abducens nerve. Light touching of the cornea should result in retraction of the globe and protrusion of the nictitating membrane.
reflex walking
spinal reflexes can provide support and uncoordinated use of the hindlegs that resembles walking, in dogs with transection of the spinal cord between T13 and L4.
whisker reflex
pinching the pinna elicits a twitch of the whiskers in cats; used in assessment of depth of anesthesia.