- A reaction that is involuntary. The corneal reflex is the blink that occurs with irritation of the eye. The nasal reflex is a sneeze.
* * *1. An involuntary reaction in response to a stimulus applied to the periphery and transmitted to the nervous centers in the brain or spinal cord. Most of the deep reflexes listed as subentries are stretch or myotatic reflexes, elicited by striking a tendon or bone, causing stretching, even slight, of the muscle, which then contracts as a result of the stimulus applied to its proprioceptors. SEE ALSO: phenomenon. 2. A reflection. [L. reflexus, pp. of reflecto, to bend back]- abdominal reflexes contraction of the muscles of the abdominal wall upon stimulation of the skin (superficial a. reflexs) or tapping neighboring bony structures (deep a. reflexs). SYN: supraumbilical r. (2).- abdominocardiac r. mechanical stimulation (usually distention) of abdominal viscera causing changes (usually a slowing) in the heart rate or the occurrence of extrasystoles.- Abrams heart r. a contraction of the myocardium when the skin of the precordial region is irritated.- accommodation r. increased convexity of the lens, due to contraction of the ciliary muscle and relaxation of the suspensory ligament, to maintain a distinct retinal image.- Achilles r., Achilles tendon r. a contraction of the calf muscles when the tendo calcaneus is sharply struck. SYN: ankle jerk, ankle r., tendo Achillis r., triceps surae r..- acoustic r. contraction of the stapedius muscle in response to intense sound, increasing impedance of the middle ear and thereby protecting the inner ear from the sound. SYN: cochleostapedial r., stapedial r..- acousticopalpebral r. SYN: cochleopalpebral r..- acquired r. SYN: conditioned r..- acromial r. contraction of the biceps muscle caused by a tap on the acromion or the coracoid process.- adductor r. contraction of the adductors of the thigh caused by tapping the tendon of the adductor magnus muscle while the thigh is abducted.- allied reflexes reflexes that, acting toward a common purpose, can traverse the final common path together.- antagonistic reflexes reflexes that do not act toward a common purpose, and cannot together traverse the final common path.- aponeurotic r. plantar flexion of the foot and toes elicited by tapping the sole near its outer edge; has the same significance as the Rossolimo toe flexion r.. SYN: Guillain-Barré r., sole tap r., Weingrow r..- attitudinal reflexes SYN: statotonic reflexes.- auricular r. a movement of the ears in animals in response to a sound; part of the investigatory r..- auriculopalpebral r. SYN: Kisch r..- auriculopressor r. peripheral vasoconstriction and a rise in blood pressure in response to a fall in pressure in the great veins. SYN: Pavlov r..- auropalpebral r. SYN: cochleopalpebral r..- axon r. a response elicited by peripheral nerve stimulation; attributed to impulses traveling proximally from the stimulation site along motor axons, encountering a branch point, and then passing distally down the other branch to activate local arterioles (to cause vasodilation) or muscle (to cause contractions). Latency of the response decreases with more proximal stimulation; axon r. is eliminated by axon degeneration or strong stimuli but not by proximal anesthetic blocks of the nerve.- Bainbridge r. an increase in heart rate caused by a rise in pressure of the blood in the right atrium due to increased flow and/or pressure in the great veins at its entrance.- Barkman r. contraction of the ipsilateral rectus muscle in response to a stimulus applied to the skin below a nipple.- basal joint r. opposition and adduction of the thumb with flexion at its metacarpophalangeal joint and extension at its interphalangeal joint, when firm passive flexion of the third, fourth, or fifth finger is made; the r. is present normally but is absent in pyramidal lesions. SYN: finger-thumb r., Mayer r..- Bechterew-Mendel r. plantar flexion of the toes caused by percussion of the dorsum of the foot; present in a pyramidal lesion. SYN: dorsum pedis r., Mendel-Bechterew r..- behavior r. SYN: conditioned r..- Benedek r. plantar flexion of the foot caused by tapping the anterior margin of the lower part of the fibula, while the foot is slightly dorsiflexed.- Bezold-Jarisch r. a r. with afferent and efferent pathways in the vagus, originating in unidentified chemoreceptors in the heart and resulting in sinus bradycardia, hypotension, and probable peripheral vasodilation.- biceps femoris r. contraction of the biceps femoris upon tapping its lower part, just above its attachment to the head of the fibula, while the limb is partly flexed at hip and knee.- Bing r. when the foot is passively dorsiflexed, plantar flexion occurs if any point on the ankle between the two malleoli is tapped.- body righting reflexes r. effects upon the neck muscles that bring the head into the correct position in space caused by stimulation of pressoreceptors in the body wall by contact with the ground.- brachioradial r. with the arm supinated to 45°, a tap near the lower end of the radius causes contraction of the brachioradial (supinator longus) muscle. SYN: radioperiosteal r., styloradial r., supination r., supinator jerk, supinator r., supinator longus r..- Brissaud r. tickling the sole causes a contraction of the tensor fasciae latae muscle, even when there is no responsive movement of the toes.- bulbocavernosus r. a sharp contraction of the bulbocavernosus and ischiocavernosus muscles when the glans penis is suddenly compressed or tapped.- bulbomimic r. in a case of coma from severe apoplexy, pressure on the eyeballs causes contraction of the facial muscles of expression on the side opposite to the lesion; if coma due to diabetes, uremia, or other toxic cause the r. is present on both sides. SYN: facial r., Mondonesi r..- cardiac depressor r. a fall in blood pressure due to peripheral vasodilation and cardiac inhibition by stimulations of terminations of a cardiac depressor nerve in the aortic arch and base of the heart. SYN: aortic r., depressor r..- carotid sinus r. a normal r. relating to the carotid sinus syndrome, which results from hypersensitivity or hyperactivation of the carotid sinus.- celiac plexus r. arterial hypotension coincident with surgical manipulations in the upper abdomen during general anesthesia.- cephalopalpebral r. contraction of the orbicularis muscle elicited by tapping the vertex of the skull.- chin r. SYN: jaw r..- Chodzko r. contractions of several muscles of the shoulder girdle and arm when the manubrium sterni is percussed.- clasping r. the strong flexion of the forelimbs of amphibia and certain other animals during the mating season when the chest or abdomen is stimulated; it is dependent upon the male sex hormone.- cochleo-orbicular r. SYN: cochleopalpebral r..- cochleopalpebral r. a form of the wink r. in which there is a contraction, sometimes very slight, of the orbicularis palpebrarum muscle to an intense sound. SEE ALSO: startle r.. SYN: acousticopalpebral r., auropalpebral r., cochleo-orbicular r..- cochleopupillary r. mydriasis in response to a sudden and unexpected loud noise; a normal response.- cochleostapedial r. SYN: acoustic r..- conditioned r. (CR) a r. that is gradually developed by training and association through the frequent repetition of a definite stimulus. See conditioning. SYN: acquired r., behavior r., trained r..- corneal r. 1. a contraction of the eyelids when the cornea is lightly touched with a camel-hair pencil; SYN: lid r.. 2. reflection of light from the surface of the cornea.- costal arch r. contraction of the rectus abdominis muscle by tapping the costal margin inside the mammary line.- costopectoral r. SYN: pectoral r..- cough r. the r. that mediates coughing in response to irritation of the larynx or tracheobronchial tree. SYN: laryngeal r..- craniocardiac r. stimulation of nerve endings of certain cranial nerves ( e.g., olfactory, ophthalmic branch of trigeminal), with resultant cardiac depressor r., manifested by bradycardia and hypotension, through the cardiac branch of the vagus.- cremasteric r. a drawing up of the scrotum and testicle of the same side when the skin over the Scarpa triangle or on the inner side of the thigh is scratched.- crossed r. a r. movement on one side of the body in response to a stimulus applied to the opposite side. SYN: crossed jerk.- crossed adductor r. contraction of the adductors of the thigh and inward rotation of the limb elicited by tapping the sole. SYN: crossed adductor jerk.- crossed extension r. extension of the contralateral hind limb when the paw of an animal is painfully stimulated or the central cut end of an afferent nerve, e.g., the peroneal, is stimulated; sometimes occurs in humans upon tapping the skin.- crossed knee r. contraction of the contralateral quadriceps when a patellar r. is elicited. SYN: crossed knee jerk.- crossed r. of pelvis contraction of the contralateral adductors of the thigh upon tapping the anterior superior iliac spine. SYN: crossed spino- adductor r..- cuboidodigital r. flexion of the toes on tapping over the cuboid bone; almost identical with Guillain-Barré r., and fundamentally similar to Rossolimo r.. SYN: metatarsal r..- cutaneous r. wrinkling of the skin, caused by a cutaneous stimulus, due to contraction of arrectores pilorum muscles.- deep r. an involuntary muscular contraction following percussion of a tendon or bone. SYN: jerk (2).- deep abdominal reflexes contraction of abdominal muscles elicited by stimulation, such as tapping a deep structure; e.g., the costal margin. SEE ALSO: Galant r., upper abdominal periosteal r..- defense r. 1. SYN: flexor r.. 2. automatic reactions of an animal, e.g., raising of hair or feathers, dilation of the pupils, or baring of claws, when alarmed.- deglutition r. SYN: swallowing r..- delayed r. a r. in which a little time elapses between stimulus and response. SEE ALSO: trace conditioned r..- digital r. SYN: Hoffmann sign (2).- diving r. a r. by which immersing the face or body in water, especially cold water, tends to cause bradycardia and peripheral vasoconstriction; mean aortic pressure is little affected because the reduction in cardiac output tends to balance the increased peripheral resistance that reduces peripheral blood flow. Although relatively minor in most humans, the changes can be profound in some diving species of animal, e.g., ducks and seals.- dorsal r. contraction of the muscles of the back elicited by cutaneous stimulation over the erector spinal muscle.- enterogastric r. peristaltic contraction of the small intestine induced by the entrance of food into the stomach. SEE ALSO: gastrocolic r..- epigastric r. a contraction of the upper portion of the rectus abdominis muscle when the skin of the epigastrium above is scratched. SYN: supraumbilical r. (1).- erector-spinal r. a contraction of part of the erector spinae muscle following scratching of the skin on its outer border.- esophagosalivary r. salivation caused by irritation of the lower end of the esophagus, as by carcinoma. SYN: Roger r..- external oblique r. contraction of the external oblique and rectus abdominis muscles upon tapping the anterior and outer part of the lower thoracic wall.- eye r. SYN: light r. (2).- eyeball-heart r. slowing of the heart rate due to the vagal effects of compressing an eyeball. SYN: eyeball compression r..- facial r. SYN: bulbomimic r..- faucial r. SYN: gag r..- femoral r. scratching the skin of the upper part of the front of the thigh causes extension of the knee and flexion of the foot.- femoroabdominal r. contraction of the abdominal muscles upon stroking the inner aspect of the thigh; in association with the cremasteric r.. SYN: hypogastric r..- Ferguson r. enhancement of uterine activity due to mechanical stretching of the lower uterine segment and cervix.- flexor r. flexion of ankle, knee, and hip when the foot is painfully stimulated; the crossed extension r. occurs in association with it. SYN: defense r. (1), nociceptive r., withdrawal r..- forced grasping r. SYN: grasping r..- front-tap r. contraction of the gastrocnemius muscle when the shin is struck. SYN: periosteal r. (1).- gag r. contact of a foreign body with the mucous membrane of the fauces causes retching or gagging. SYN: faucial r..- Galant r. a deep abdominal r. in which there is a contraction of the abdominal muscles on tapping the anterior superior iliac spine. SYN: lower abdominal periosteal r..- gastrocolic r. a mass movement of the contents of the colon, frequently preceded by a similar movement in the small intestine, that sometimes occurs immediately following the entrance of food into the stomach.- Geigel r. in the female, a contraction of the muscular fibers at the upper edge of the Poupart ligament on gently stroking the inner side of the thigh; analogue of the cremasteric r. in males.- Gordon r. dorsal flexion of the great toe produced by firm lateral pressure on the calf muscles. SYN: paradoxical flexor r..- grasp r. SYN: grasping r..- grasping r. an involuntary flexion of the fingers to tactile or tendon stimulation on the palm of the hand, producing an uncontrollable grasp; usually associated with frontal lobe lesions. Cf.:darwinian r.. SYN: forced grasping r., grasp r..- great-toe r. SYN: Babinski sign (1).- gustatory-sudorific r. sweating, especially over the face, when chewing food. SEE ALSO: auriculotemporal nerve syndrome.- H r. a monosynaptic r. consistently obtained in normal adults only by stimulating the tibial nerve, generally in the popliteal fossa, while recording from the gastrocnemius-soleus muscle group; similar to the Achilles r., except the neuromuscular spindles are bypassed; widely used in the EMG laboratory to diagnose S1 radiculopathies and polyneuropathies.- hepatojugular r. hepatojugular reflux.- Hering-Breuer r. the effects of afferent impulses from the pulmonary vagi in the control of respiration; e.g., inflation of the lungs arrests inspiration with expiration then ensuing, whereas deflation of the lungs brings on inspiration.- Hoffmann r. SYN: Hoffmann sign (2).- hypogastric r. SYN: femoroabdominal r..- innate r. an unlearned or instinctive r. such as sucking, which is present at birth. SYN: inborn r..- intrinsic r. a r. muscular contraction elicited by the application of a stimulus, usually stretching, to the muscle itself as opposed to a muscular contraction caused by an extrinsic stimulus, e.g., skin, as in the abdominal skin reflexes.- inverted r. SYN: paradoxical r..- inverted radial r. flexion of the fingers without flexion of the forearm, on tapping the lower end of the radius; regarded as indicating a lesion of the fifth cervical segment of the spinal cord.- investigatory r. SYN: orienting r..- Jacobson r. flexion of the fingers elicited by tapping the flexor tendons over the wrist joint or the lower end of the radius.- jaw r. a spasmodic contraction of the temporal muscles following a downward tap on the loosely hanging mandible. SYN: chin jerk, chin r., jaw jerk, mandibular r., masseter r..- jaw-working r. SYN: jaw-winking syndrome.- Joffroy r. twitching of the glutei muscles when firm pressure is made on the nates, in cases of spastic paralysis. SYN: hip phenomenon.- Kisch r. closure of the eye in response to stimulation of the skin at the depth of the external auditory meatus. SYN: auriculopalpebral r..- labyrinthine reflexes reflexes initiated through stimulation of receptors in the utricle or semicircular canals. SEE ALSO: statotonic reflexes, statokinetic r., righting reflexes.- labyrinthine righting reflexes stimulation of the receptors of the labyrinth causes changes in tone of the neck muscles that bring the head into position.- lacrimogustatory r. chewing of food causing secretion of tears. SEE ALSO: crocodile tears syndrome.- laryngospastic r. SYN: laryngospasm.- latent r. a r. that must be considered normal but that usually appears only under some pathologic circumstance that lowers its threshold.- laughter r. uncontrollable laughter excited by tickling.- let-down r. SYN: milk-ejection r..- lid r. SYN: corneal r. (1).- light r. 1. SYN: pupillary r.. 2. a red glow reflected from the fundus of the eye when a light is cast upon the retina, as in retinoscopy; SYN: eye r., fundus r.. 3. a triangular area at the anterior inferior part of the tympanic membrane, extending from the umbo to the periphery, where there is seen a reflection of light. SYN: cone of light, Politzer luminous cone, pyramid of light, red r., Wilde triangle.- lip r. a pouting movement of the lips provoked in young infants by tapping near the angle of the mouth.- Lovén r. a reaction in which a local dilation of vessels accompanies a general vasoconstriction; e.g., when the central end of an afferent nerve to an organ is suitably stimulated, its efferent vasomotor fibers remaining intact, a general rise in blood pressure occurs together with a dilation of the vessels of the organ.- mandibular r. SYN: jaw r..- mass r. in cases of gross injury to the spinal cord, as the stage of r. activity follows the primary flaccidity of the shock, a condition arises in which a strong stimulus to any part of one of the paralyzed limbs will be followed by contraction of the hip, knee, and ankle of the same side and often, when the stimulus is applied to the middle line of the body, of both sides, as well as of the abdominal wall, and even evacuation of the bladder and sweating over an area corresponding to the level of the lesion.- masseter r. SYN: jaw r..- mediopubic r. contraction of the adductors of the thigh upon tapping the pubic bone near the symphysis.- Mendel instep r. the foot being firmly supported on its inner side, a sharp tap on the dorsal tendons causes extension of the second to the fifth toes. SYN: back of foot r., dorsum of foot r..- metacarpohypothenar r. flexion of the little finger on tapping the dorsum of the hand; seen in pyramidal tract lesions; similar to Starling r..- metacarpothenar r. SYN: thumb r..- metatarsal r. SYN: cuboidodigital r..- micturition r. contraction of the walls of the bladder and relaxation of the trigone and urethral sphincter in response to a rise in pressure within the bladder; the r. can be voluntarily inhibited and the inhibition readily abolished to control micturition. SYN: bladder r., urinary r., vesical r..- milk-ejection r. release of milk from the breast following tactile stimulation of the nipple; the afferent path is postulated to exist from the nipple to the hypothalamus; the efferent limb is represented by the neurohypophysial release of oxytocin into the systemic circulation; contraction of myoepithelial elements within the breast, caused by oxytocin, moves milk into the collecting ducts and toward the nipple. SYN: let-down r., milk let-down r..- Mondonesi r. SYN: bulbomimic r..- Moro r. SYN: startle r..- myenteric r. contraction above and relaxation below a stimulated point in the intestine. SYN: law of intestine.- myotatic r. tonic contraction of the muscles in response to a stretching force, due to stimulation of muscle proprioceptors. SYN: deep tendon r., Liddell-Sherrington r., muscular r., stretch r..- near r. pupillary constriction with a near vision effort, with ocular convergence, or with accommodation; an associated reaction, not a true r..- neck reflexes changes in position of the head cause alterations in tone of the neck muscles through stimulation of proprioceptors in the labyrinth which bring the head into its correct position in space; stimulation of proprioceptors in the neck muscles causes in turn r. movements of the limbs which bring the animal into the normal position in relation to the head.- oculocardiac r. a decrease in pulse rate associated with traction on extraocular muscles or compression of the eyeball; especially sensitive in children; may produce asystolic cardiac arrest. SYN: Aschner phenomenon, Aschner r., Aschner-Dagnini r..- oculocephalic r. SYN: oculocephalogyric r..- oculocephalogyric r. turning of the eyes and head toward the source of an auditory, visual, or other form of stimulation. SYN: oculocephalic r..- oculovagal r. See oculocardiac r..- Oppenheim r. extension of the toes induced by scratching of the inner side of the leg or by following sudden flexion of the thigh on the abdomen and the leg on the thigh; a sign of cerebral irritation.- optical righting reflexes visual stimuli that enable an animal to maintain the correct position of the head in space, by bringing about movements of the muscles of the neck and limbs.- orbicularis oculi r. contraction of the orbicularis oculi muscles upon tapping the margin of the orbit, or the bridge or tip of the nose. SYN: nose-bridge-lid r., nose-eye r..- orienting r. an aspect of attending in which an organism's initial response to a change or to a novel stimulus is such that the organism becomes more sensitive to the stimulation; e.g., dilation of the pupil of the eye in response to dim light. SYN: investigatory r., orienting response.- palm-chin r. SYN: palmomental r..- palmomental r. unilateral (sometimes bilateral) contraction of the mentalis and orbicularis oris muscles caused by a brisk scratch made on the palm of the ipsilateral hand. SYN: palm-chin r..- parachute r. SYN: startle r..- paradoxical r. any r. in which the usual response is reversed or does not conform to the pattern characteristic of the particular r.. SYN: inverted r..- paradoxical patellar r. 1. a tap on the patellar tendon causes contraction of the adductor; 2. sudden passive extension of the leg causes a contraction of the extensor muscles of the leg.- paradoxical pupillary r. constriction of pupils in darkness, the reverse of that expected. SYN: Flynn phenomenon, paradoxical pupillary phenomenon.- patellar r. a sudden contraction of the anterior muscles of the thigh, caused by a smart tap on the patellar tendon while the leg hangs loosely at a right angle with the thigh. SYN: knee jerk, knee r., knee-jerk r., patellar tendon r., quadriceps r..- Pavlov r. SYN: auriculopressor r..- pectoral r. contraction of the pectoralis major muscle elicited by tapping the seventh rib between the anterior and the medial axillary lines while the arm is abducted; contraction of the deltoid and biceps may also occur. SYN: costopectoral r..- Perez r. running a finger down the spine of an infant held supported in a prone position will normally cause the whole body to become extended.- pericardial r. a vagal r. seen during operations involving pericardial manipulation; characterized by signs of vagal stimulation (bradycardia and arterial hypotension).- periosteal r. 1. SYN: front-tap r.. 2. a muscular contraction in the arm following a tap on the radius or ulna.- Phillipson r. a contraction of the extensors of the knee when the extensors of the opposite knee are inhibited.- photic-sneeze r. SYN: photoptarmosis.- pilomotor r. contraction of the smooth muscle of the skin resulting in “gooseflesh” caused by mild application of a tactile stimulus or by local cooling.- plantar r. the response to tactile stimulation of the ball of the foot, normally plantar flexion of the toes; the pathologic response is Babinski sign (1). SYN: sole r..- pneocardiac r. a modification in the blood pressure or heart rhythm caused by the inhalation of an irritating vapor.- pneopneic r. a modification of the respiratory rhythm caused by the inhalation of an irritating vapor.- postural r. responses that control the position of the trunk and extremities. SEE ALSO: righting reflexes. SYN: static reflexes (1).- proprioceptive reflexes any r. brought about by stimulation of proprioceptors. SEE ALSO: proprioceptor.- proprioceptive-oculocephalic r. SYN: vestibuloocular r..- protective laryngeal r. closure of the glottis to prevent entry of foreign substances into the respiratory tract.- psychocardiac r. a change in the circulatory rate and subjective heart consciousness (often “thumping”) resulting from a memory of, or a subconscious dream state recollection of, an emotional impression or experience.- pulmonocoronary r. r. constriction of the coronary arteries as a result of vagal stimuli arising in the lungs, as in pulmonary embolism.- pupillary r. change in diameter of the pupil as a r. response to any type of stimulus; e.g., constriction caused by light. SYN: light r. (1).- pupillary-skin r. dilation of the pupil following scratching of the skin of the neck. SYN: ciliospinal r., cutaneous pupil r., cutaneous-pupillary r., skin-pupillary r..- quadripedal extensor r. extension of the arm of a hemiplegic patient when turned prone as if on all fours. SYN: Brain r..- radial r. on tapping the lower end of the radius, flexion of the forearm occurs, and sometimes, on strong percussion, flexion of the fingers. SEE ALSO: inverted radial r..- radiobicipital r. contraction of the biceps muscle that sometimes occurs in the elicitation of the brachioradial r..- radioperiosteal r. SYN: brachioradial r..- rectal r. the entrance of fecal matter into the rectum from the sigmoid colon causes an impulse to defecate.- rectocardiac r. a parasympathetic r. producing bradycardia and hypotension upon stimulation of the pelvic nerve, the afferent limb being the sacral outflow of the parasympathetic division of the autonomic nervous system, and the efferent limb, the cardiac vagus; said to accompany proctologic examinations.- red r. SYN: light r. (3).- Remak r. plantar flexion of the first three toes and, sometimes, the foot with extension of the knee induced by stroking of the upper anterior surface of the thigh; it occurs when the conducting paths in the cord are interrupted.- renal r. anuria caused by injury to a remote part of the body or by disease or injury to one kidney or ureter.- righting reflexes reflexes that through various receptors, in labyrinth, eyes, muscles, or skin tend to bring an animal's body into its normal position in space and that resist any force acting to put it into a false position, e.g., on its back. SEE ALSO: body righting reflexes, labyrinthine righting reflexes, neck reflexes, optical righting reflexes. SYN: static reflexes (2).- Roger r. SYN: esophagosalivary r..- rooting r. in infants, rubbing or scratching about the mouth causes a puckering of the lips.- Rossolimo r. flicking the tops of the toes from the plantar surface causes flexion of the toes; a stretch r. of the flexors of the toes seen in lesions of the pyramidal tracts. SEE ALSO: Starling r.. SYN: plantar muscle r., Rossolimo sign.- scapular r. contraction of the upper muscles of the back by stimulation between the scapulae. SYN: interscapular r..- scapulohumeral r. contraction of muscles of the shoulder girdle and arm caused by tapping the lower part of the unilateral border of the scapula; the muscles that respond vary according to their degree of stretching at the time. SYN: scapuloperiosteal r..- scapuloperiosteal r. SYN: scapulohumeral r..- Schäffer r. in cases of injury to the corticospinal tract, the great toe is dorsiflexed when the skin over the Achilles tendon is pinched.- semimembranosus r., semitendinosus r. contraction of these muscles by tapping in the region of the tuberosity of the tibia.- skin-muscle reflexes superficial or cutaneous reflexes, such as the superficial abdominal reflexes. SYN: skin reflexes.- snapping r. SYN: Hoffmann sign (2).- snout r. pouting or pursing of the lips induced by light tapping of the closed lips in the midline; considered a sign of frontal lobe dysfunction.- spinoadductor r. contraction of the adductors of the thigh upon tapping the spinal column. SYN: McCarthy reflexes (1).- Starling r. tapping the volar surfaces of the fingers causes flexion of the fingers; analogous to Rossolimo r., for the toes.- startle r. the r. response of an infant (contraction of the limb and neck muscles) when allowed to drop a short distance through the air or startled by a sudden noise or jolt; SYN: Moro r., parachute r., startle reaction. SEE ALSO: cochleopalpebral r..- static reflexes 1. SYN: postural r.. 2. SYN: righting reflexes.- statokinetic r. a r. that, through stimulation of the receptors in the neck muscles and semicircular canals, brings about movements of the limbs and eyes appropriate to a given movement of the head in space.- statotonic reflexes reflexes in which utricular receptors in the vestibular apparatus sense changes in the head's position in space in terms of linear acceleration and the earth's gravitational field while receptors in the neck muscles sense changes in the position of the head relative to the trunk; input from these receptors reflexly controls the tone of the limb muscles to maintain or regain the desired posture. SYN: attitudinal reflexes.- stretch r. SYN: myotatic r..- styloradial r. SYN: brachioradial r..- suckling r. the r. liberation of prolactin from the anterior lobe of the hypophysis evoked by stimulation of nerves in the nipple during the act of suckling by the newborn animal.- superficial r. any r., e.g., the abdominal or cremasteric r., that is elicited by stimulation of the skin.- supination r. SYN: brachioradial r..- supporting reflexes SYN: supporting reactions, under reaction.- supraorbital r. contraction of the orbicularis oculi muscle induced by electrical or mechanical stimulation of the supraorbital nerve. SYN: McCarthy reflexes (2), trigeminofacial r..- suprapatellar r. the patella rises when a tap is given on the quadriceps tendon above the patella.- swallowing r. the act of swallowing (second stage) induced by stimulation of the palate, fauces, or posterior pharyngeal wall. SYN: deglutition r., pharyngeal r. (1).- tarsophalangeal r. extension of all the toes except the first, when the outer part of the tarsus is tapped; in certain cerebral diseases the reverse takes place, the toes being flexed.- tendon r. a myotatic or deep r. in which the muscle stretch receptors are stimulated by percussing the tendon of a muscle.- tensor tympani r. contraction of the tensor tympani muscle in response to intense sound, increasing impedance of the middle ear and thus protecting the inner ear from exposure.- tonic r. the occurrence of an appreciable interval after the production of a r. before relaxation, e.g., the leg remains up for a time after a knee jerk. SYN: Gordon symptom.- trace conditioned r. a conditioned r. established by applying the stimulus a short time before reinforcement; in the conditioned r. of the animal so prepared, the response occurs at the same interval of time after the application of the stimulus as during the period of training.- trained r. SYN: conditioned r..- triceps r. a sudden contraction of the triceps muscle caused by a smart tap on its tendon when the forearm hangs loosely at a right angle with the arm. SYN: elbow jerk, elbow r..- trigeminofacial r. SYN: supraorbital r..- trochanter r. contraction of the adductor muscles of the thigh elicited by a tap on the trochanter.- Trömner r. a modified Rossolimo r. in which, with the fingers of the patient partially flexed, the tapping of the volar aspect of the tip of the middle or index finger causes flexion of all four fingers and thumb; seen in pyramidal tract lesions with moderate spasticity.- ulnar r. pronation and adduction of the hand caused by tapping the styloid process of the ulna. SYN: pronator r..- upper abdominal periosteal r. percussing the lower margin of the costal cartilages in the nipple line causes a contraction of the ipsilateral abdominal muscles (inconstant).- utricular reflexes statotonic reflexes.- vagovagal r. bradycardia with arterial hypotension, often with supraventricular arrhythmias; ascribed to stimulation, especially mechanical, of afferent vagal pathways in the abdomen, thorax, or airway, the efferent arc being vagal cardioinhibitory fibers.- vasopressor r. vasoconstriction caused by stimulation of certain afferent fibers, e.g., in vagus nerve.- venorespiratory r. stimulation of respiration and increased pulmonary ventilation in response to an increase in pressure in the right atrium.- vestibuloocular r. generic term for the r. control of the vestibular system over extraocular motility manifest as nystagmus in clinical testing. SYN: proprioceptive-oculocephalic r..- visceral traction r. laryngeal spasm precipitated during an operation by traction on the stomach, gallbladder, or appendiceal mesentery.- viscerogenic r. any of a number of reflexes, such as headache, cough, disturbed pulse, etc., caused by disordered conditions of any of the viscera.- visceromotor r. contraction of the muscles of the thorax or abdomen in response to a stimulus from one of the viscera therein.- viscerosensory r. an area of pain or sensitivity to pressure in the external body wall due to disease of one of the viscera. SEE ALSO: Head lines, under line.- viscerotrophic r. a degenerative change in the skeletal soft tissues consequent upon a chronic inflammatory condition of any of the thoracic or abdominal viscera.- visual orbicularis r. contraction of the orbicularis oculi muscle caused by a sudden visual stimulus. SEE ALSO: wink r..- vomiting r. vomiting (contraction of the abdominal muscles with relaxation of the cardiac sphincter of the stomach and of the muscles of the throat) elicited by a variety of stimuli, especially one applied to the region of the fauces. SYN: pharyngeal r. (2).- Weingrow r. SYN: aponeurotic r..* * *Randomized Evaluation of Flosequinan on Exercise Tolerance [study]; Restenosis Rates with Flexible GFX Stents [study]
* * *re·flex 'rē-.fleks n1 a) reflected heat, light, or colorb) a mirrored image2 a) an automatic and often inborn response to a stimulus that involves a nerve impulse passing inward from a receptor to the spinal cord and thence outward to an effector (as a muscle or gland) without reaching the level of consciousness and often without passing to the brain <the knee-jerk \reflex>b) the process that culminates in a reflex and comprises reception, transmission, and reactionc) reflexes pl the power of acting or responding with adequate speedreflex adj1) bent, turned, or directed back: REFLECTED2) of, relating to, or produced by a reflex without intervention of consciousness
* * *n.an automatic or involuntary activity brought about by relatively simple nervous circuits, without consciousness being necessarily involved. Thus a painful stimulus such as a pinprick will bring about the reflex of withdrawing the finger before the brain has had time to send a message to the muscles involved. See conditioned reflex, patellar reflex, plantar reflex, pupillary reflex, rooting reflex..
* * *re·flex (reґfleks) [L. reflexus, past part. of reflectere to bend back] 1. reflected. 2. a reflected action or movement; the sum total of any particular involuntary activity. See reflex arc and reflex action. 3. a reflection or a reflected image of an object.
Medical dictionary. 2011.