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reflex (re´fleks)

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 r.'s listed as subentries are stretch or myotatic r.'s, 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. 3. consensual [L. reflexus, pp. of re-flecto, to bend back]
abdominal r.'s contraction of the muscles of the abdominal wall upon stimulation of the skin (superficial a. r.'s) or tapping neighboring bony structures (deep a. r.'s).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.ankle jerk, ankle r., tendo Achillis r., triceps surae r;
acousticopalpebral r. cochleopalpebral r
acquired r. 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 r.'s r.'s which, acting toward a common purpose, can traverse the final common path together.
anal r. contraction of the internal sphincter gripping the finger passed into the rectum.
ankle r. Achilles r
antagonistic r.'s r.'s which do not act toward a common purpose, and cannot together traverse the final common path.
aortic r. cardiac depressor r
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. Also called Guillain-Barré, Weingrow's, or sole tap r.Guillain-Barré r., sole tap r., Weingrow's r;
Aschner-Dagnini r. oculocardiac r
Aschner's r. oculocardiac r
attitudinal r.'s statotonic r.'s
auditory r. any r. occurring in response to a sound, e.g., cochleopalpebral r.
auditory oculogyric r. rotation of the eyes toward the source of a sudden sound.
auricular r. a movement of the ears in animals in response to a sound; part of the investigatory r.
auriculopalpebral r. Kisch's r
auriculopressor r. peripheral vasoconstriction and a rise in blood pressure in response to a fall in pressure in the great veins.Pavlov's r;
auropalpebral r. cochleopalpebral r
axon r. an effect brought about by the passage of the nerve impulses from a sensory ending to the effector organ along divisions of the nerve fiber without traversing a synapse, e.g., as in the vasodilation resulting from stimulation of the skin or the irritation of the conjunctiva; the reaction occurs even when the nerve fiber has been sectioned and thus isolated from the nervous centers.
Babinski r. Babinski's sign (1)
back of foot r. , dorsum of foot r. Mendel's instep r
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's 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.finger-thumb r., Mayer's r;
Bechterew-Mendel r. percussion of the dorsum of the foot causes flexion of the toes; present in a pyramidal lesion.dorsum pedis r., Mendel-Bechterew r;
behavior r. conditioned r
Benedek's r. plantar flexion of the foot 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 r. contraction of the biceps muscle when its tendon is struck.
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's r. when the foot is passively dorsiflexed, plantar flexion occurs if any point on the ankle between the two malleoli is tapped.
bladder r. micturition r
body righting r.'s r. effects upon the neck muscles which bring the head into the correct position in space caused by stimulation of pressoreceptors in the body wall by contact with the ground.
bone r. a r. excited by a stimulus applied to a bone.
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.radioperiosteal r., styloradial r., supination r., supinator jerk, supinator r., supinator longus r;
Brain's r. quadripedal extensor r
bregmocardiac r. in infants, pressure upon the anterior fontanelle causing cardiac slowing.
Brissaud's 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.facial r., Mondonesi's r;
Capps' r. obsolete eponym for vasomotor collapse at the time of crisis in pneumonia.
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.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.
cephalic r.'s r.'s associated with the cranial nerves.
cephalopalpebral r. contraction of the orbicularis muscle elicited by tapping the vertex of the skull.
Chaddock r. Chaddock sign
chain r. a series of r.s, each serving as a stimulus for the next.
chin r. jaw r
Chodzko's r. contractions of several muscles of the shoulder girdle and arm when the manubrium sterni is percussed.
ciliospinal r. pupillary-skin r
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. cochleopalpebral r
cochleopalpebral r. a form of the wink r. in which there is a contraction, sometimes very slight, of the orbicularis palpebrarum muscle when a sudden noise is made close to the ear; it is absent in labyrinthine disease with total deafness.acousticopalpebral r., auropalpebral r., cochleo-orbicular r., startle r. (2);
cochleopupillary r. constriction of the pupil in response to a sudden loud sound. The normal response to such a stimulus is pupil dilation.
cochleostapedial r. contraction of the stapedius muscle in response to a loud sound; this is a protective r. which with the r. contraction of the tensor tympani reduces the amplitude of the vibrations of the tympanic membrane and ossicles.
conditioned r. (CR) a r. that is gradually developed by training and association through the frequent repetition of a definite stimulus. See conditioning.acquired r., behavior r., trained r;
conjunctival r. closure of the eyes in response to irritation of the conjunctiva.
consensual light r. consensual reaction
contralateral r. Brudzinski's sign (1)
convulsive r. an incoordinated r. in which muscles, even those opposing one another as in strychnine poisoning, contract.
coordinated r. a r. in which several muscles take part in the performance of a purposeful act.
corneal r. 1. a contraction of the eyelids when the cornea is lightly touched with a camel-hair pencil;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. pectoral r
cough r. the r. which mediates coughing in response to irritation of the larynx or tracheobronchial tree.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 Scarpa's 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.crossed jerk;
crossed adductor r. contraction of the adductors of the thigh and inward rotation of the limb elicited by tapping the sole.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.crossed knee jerk;
crossed r. of pelvis contraction of the contralateral adductors of the thigh upon tapping the anterior superior iliac spine.crossed spino-adductor r;
crossed spino-adductor r. crossed r. of pelvis
cry r. a sudden unconscious cry, during sleep, in a child with hip disease, long bone fractures, or other painful conditions of the extremities, elicited by movement of muscles that have relaxed after prolonged muscle spasms.
cuboidodigital r. flexion of the toes on tapping over the cuboid bone; almost identical with Guillain-Barré r., and fundamentally similar to Rossolimo's r.metatarsal r;
cutaneous r. wrinkling of the skin, caused by a cutaneous stimulus, due to contraction of arrectores pilorum muscles.
cutaneous pupil r. , cutaneous-pupillary r. pupillary-skin r
darwinian r. the tendency of young infants to grasp a bar and hang suspended. Cf. grasping r.
deep r. an involuntary muscular contraction following percussion of a tendon or bone.jerk (2);
deep abdominal r.'s contraction of abdominal muscles elicited by stimulation, such as tapping a deep structure; e.g., the costal margin. See also Galant's r., upper abdominal periosteal r.
defense r. 1. 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. swallowing r
Dejerine's r. Dejerine's hand phenomenon
delayed r. a r. in which a little time elapses between stimulus and response. See also trace conditioned r.
depressor r. cardiac depressor r
diffused r. one of several r.'s occurring in association with the main r.
digital r. Hoffmann's 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.
dorsum pedis r. Bechterew-Mendel r
elbow r. triceps r
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.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.Roger's 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. light r. (2)
eyeball compression r. eyeball-heart r
eyeball-heart r. slowing of the heart rate due to the vagal effects of compressing an eyeball.eyeball compression r;
eye-closure r. wink r
facial r. bulbomimic r
faucial r. 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.hypogastric r;
finger-thumb r. basal joint r
flexor r. flexion of ankle, knee, and hip when the foot is painfully stimulated; the crossed extension r. occurs in association with it.defense r. (1), nociceptive r., withdrawal r;
forced grasping r. grasping r
front-tap r. contraction of the gastrocnemius muscle when the shin is struck.periosteal r. (1);
fundus r. light r. (2)
gag r. contact of a foreign body with the mucous membrane of the fauces causes retching or gagging.faucial r;
Galant's r. a deep abdominal r. in which there is a contraction of the abdominal muscles on tapping the anterior superior iliac spine.lower abdominal periosteal r;
galvanic skin r. galvanic skin response
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.
gastroileac r. opening of the ileocolic valve induced by entrance of food into the stomach.
Geigel's r. in the female, a contraction of the muscular fibers at the upper edge of Poupart's ligament on gently stroking the inner side of the thigh; analogue of the cremasteric r. in males.
Gifford's r. eye-closure pupil reaction
gluteal r. contraction of the gluteal muscles following irritation of the skin of the buttocks.
Gordon r. dorsal flexion of the great toe produced by firm lateral pressure on the calf muscles.paradoxical flexor r;
grasp r. 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. forced grasping r., grasp r;
great-toe r. Babinski's sign (1)
Guillain-Barré r. aponeurotic r
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. See 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, while deflation of the lungs brings on inspiration.
Hoffmann's r. Hoffmann's sign (2)
hypochondrial r. a quick inspiration induced by sharp pressure beneath the costal margin.
hypogastric r. femoroabdominal r
inborn r. a r. such as breathing that is innate.
innate r. an unlearned or instinctive r. such as sucking, which is present at birth.
interscapular r. scapular 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 r.'s.
inverted r. 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. orienting r
ipsilateral r. a r. in which the response occurs on the side of the body that is stimulated.
Jacobson's 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.chin jerk, chin r., jaw jerk, mandibular r., masseter r;
jaw-working r. jaw-winking syndrome
Joffroy's r. twitching of the glutei muscles when firm pressure is made on the nates, in cases of spastic paralysis.hip phenomenon;
Kisch's r. closure of the eye in response to stimulation of the skin at the depth of the external auditory meatus.auriculopalpebral r;
knee r. patellar r
knee-jerk r. patellar r
labyrinthine r.'s r.'s initiated through stimulation of receptors in the utricle or semicircular canals. See also statotonic r.'s, statokinetic r., righting r.'s.
labyrinthine righting r.'s stimulation of the proprioceptors of the labyrinth causes changes in tone of the neck muscles which bring the head into its natural position in space.
lacrimal r. discharge of tears when the conjunctiva is irritated.
lacrimo-gustatory r. chewing of food causing secretion of tears. See also crocodile tears syndrome.
laryngeal r. cough r
laryngospastic r. laryngospasm
latent r. a r. which must be considered normal but which usually appears only under some pathologic circumstance that lowers its threshold.
laughter r. uncontrollable laughter excited by tickling.
let-down r. milk-ejection r
lid r. corneal r. (1)
Liddell-Sherrington r. myotatic r
light r. 1. pupillary r 2. a red glow reflected from the fundus of the eye when a light is cast upon the retina, as in retinoscopy;eye r., fundus r; 3. pyramid of light
lip r. a pouting movement of the lips provoked in young infants by tapping near the angle of the mouth.
lordosis r. adoption of a copulatory posture when touched on the back; exhibited by female animals of certain species but only during the time of estrus.
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.
lower abdominal periosteal r. Galant's r
magnet r. See magnet reaction.
mandibular r. 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. jaw r
Mayer's r. basal joint r
McCarthy's r.'s 1. spino-adductor r 2. supraorbital r
mediopubic r. contraction of the adductors of the thigh upon tapping the pubic bone near the symphysis.
Mendel-Bechterew r. Bechterew-Mendel r
Mendel's 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.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 and is similar to Starling's r.
metacarpothenar r. thumb r
metatarsal r. 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.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.let-down r., milk let-down r;
milk let-down r. milk-ejection r
Mondonesi's r. bulbomimic r
Moro r. startle r. (1)
muscular r. myotatic r
myenteric r. contraction above and relaxation below a stimulated point in the of intestine;
myotatic r. tonic contraction of the muscles in response to a stretching force, due to stimulation of muscle proprioceptors.Liddell-Sherrington r., muscular r., stretch r;
nasal r. sneezing caused by irritation of the nasal mucous membrane.
nasomental r. contraction of the mentalis muscle following a tap on the side of the nose.
near r. pupillary constriction with a near vision effort, with ocular convergence, or with accommodation; an associated reaction, not a true r.
neck r.'s 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.
nociceptive r. flexor r
nocifensor r. vascular dilation in a part surrounding an injury or in its neighborhood.
nose-bridge-lid r. orbicularis oculi r
nose-eye r. orbicularis oculi r
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.Aschner's phenomenon, Aschner's r., Aschner-Dagnini r., oculovagal r
oculocephalic r. oculocephalogyric r
oculocephalogyric r. turning of the eyes and head toward the source of an auditory, visual, or other form of stimulation.oculocephalic r;
oculovagal r. oculocardiac r
olecranon r. flexion of the forearm caused by tapping the olecranon.paradoxical triceps r;
Oppenheim's 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 r.'s 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.nose-bridge-lid r., nose-eye r;
orbicularis pupillary r. eye-closure pupil reaction
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.investigatory r., orienting response;
palatal r. , palatine r. swallowing r. induced by stimulation of the palate.
palmar r. flexion of the fingers following tickling of the palm.
palm-chin r. 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.palm-chin r;
parachute r. startle r. (1)
paradoxical r. any r. in which the usual response is reversed or does not conform to the pattern characteristic of the particular r.inverted r;
paradoxical extensor r. Babinski's sign (1)
paradoxical flexor r. Gordon 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. a pupillary response to light, the reverse of that expected; e.g., contraction of the pupil in response to turning the lights off.Flynn phenomenon, paradoxical pupillary phenomenon;
paradoxical triceps r. olecranon r
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.knee jerk, knee phenomenon, knee r., knee-jerk r., patellar tendon r., quadriceps r;
patellar tendon r. patellar r
patello-adductor r. crossed adduction of the leg on tapping the quadriceps tendon.
Pavlov's r. 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.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. front-tap r 2. a muscular contraction in the arm following a tap on the radius or ulna.
pharyngeal r. 1. swallowing r 2. vomiting r
phasic r. a coordinated complex response such as the scratch r. in the spinal animal.
Phillipson's r. a contraction of the extensors of the knee when the extensors of the opposite knee are inhibited.
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's sign (1) .sole r;
plantar muscle r. Rossolimo's 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 r.'s.static r. (1);
pressoreceptor r. a normal r. related to the carotid sinus syndrome.
pronator r. ulnar r
proprioceptive r.'s any r. brought about by stimulation of proprioceptors. See also proprioceptor.
proprioceptive-oculocephalic r. vestibular ocular 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.
psychogalvanic r. , psychogalvanic skin r. galvanic skin response
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 reflex response to any type of stimulus; e.g., constriction caused by light.light r. (1);
pupillary-skin r. dilation of the pupil following scratching of the skin of the neck.ciliospinal r., cutaneous pupil r., cutaneous-pupillary r., skin-pupillary r;
quadriceps r. patellar r
quadripedal extensor r. extension of the arm of a hemiplegic patient when turned prone as if on all fours.Brain's 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 which sometimes occurs in the elicitation of the brachioradial r.
radioperiosteal r. 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.
rectolaryngeal r. laryngeal spasm precipitated by stretching the anal sphincter.
red r. pyramid of light
Remak's 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 r.'s r.'s which through various receptors, in labyrinth, eyes, muscles, or skin, tend to bring an animal's body into its normal position in space and which resist any force acting to put it into a false position, e.g., on its back. See also body righting r.'s, labyrinthine righting r.'s, neck r.'s, optical righting r.'s.static r. (2);
Roger's r. esophagosalivary r
rooting r. in infants, rubbing or scratching about the mouth causes a puckering of the lips.
Rossolimo's 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's r.plantar muscle r., Rossolimo's sign;
scapular r. contraction of the upper muscles of the back by stimulation between the scapulae.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 which respond vary according to their degree of stretching at the time.scapuloperiosteal r;
scapuloperiosteal r. scapulohumeral r
Schäffer's r. in cases of injury to the corticospinal tract, the great toe is dorsiflexed when the skin over the Achilles tendon is pinched.
scratch r. in dogs stimulus applied to the skin of a saddle-shaped area of the back, sides, and flanks produces a scratching movement of the hind leg of the side stimulated.
semimembranosus r. , semitendinosus r. contraction of these muscles by tapping in the region of the tuberosity of the tibia.
shot-silk r. shot-silk retina
sinus r. See carotid sinus syndrome.
skin r.'s skin-muscle r.'s
skin-muscle r.'s superficial or cutaneous r.'s, such as the superficial abdominal r.' r.'s;
skin-pupillary r. pupillary-skin r
snapping r. Hoffmann's sign (2)
snout r. pouting or pursing of the lips induced by light tapping of closed lips near the midline; seen in defective pyramidal innervation of facial musculature.
sole r. plantar r
sole tap r. aponeurotic r
spinal r. a r. arc involving the spinal cord. See reflex arc.
spino-adductor r. contraction of the adductors of the thigh upon tapping the spinal column.McCarthy's r.'s (1);
Starling's r. tapping the volar surfaces of the fingers causes flexion of the fingers; analogous to Rossolimo's r., for the toes.
startle r. 1. 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;Moro r., parachute r., startle reaction; 2. cochleopalpebral r
static r. 1. postural r 2. righting r.'s
statokinetic r. a r. which, 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 r.'s r.'s 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.attitudinal r.'s;
stepping r. if the plantar surface of a hind foot of a dog is pressed gently, a movement of extension of the limb will follow, accompanied sometimes by flexion of the opposite hind limb.
sternobrachial r. contraction of the adductors of the arm when the sternum is tapped.
stretch r. myotatic r
Strümpell's r. stroking the abdomen or thigh causes flexion of the leg and adduction of the foot.
styloradial r. 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., which is elicited by stimulation of the skin.
supination r. brachioradial r
supinator r. , supinator longus r. brachioradial r
supporting r.'s supporting reactions, under reaction
supraorbital r. contraction of the orbicularis oculi muscle induced by tapping the supraorbital nerve.McCarthy's r.'s (2), trigeminofacial r;
suprapatellar r. the patella rises when a tap is given on the quadriceps tendon above the patella.
supraumbilical r. 1. epigastric r 2. abdominal r.'s
swallowing r. the act of swallowing (second stage) induced by stimulation of the palate, fauces, or posterior pharyngeal wall.deglutition r., pharyngeal r. (1);
synchronous r. subsidiary r. actions occurring in association with the main or leading r.
tapetal light r. the glow from the eyes of some animals in the dark when a light illuminates the retina; due to the reflection of the light from the tapetum, an iridescent layer (containing guanidine crystals) in the choroid.
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.
tendo Achillis r. Achilles r
tendon r. a myotatic or deep r. in which the muscle stretch receptors are stimulated by percussing the tendon of a muscle.
thumb r. flexion of the thumb upon tapping the dorsum of the hand.metacarpothenar r;
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.Gordon's 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. 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.elbow jerk, elbow r;
triceps surae r. Achilles r
trigeminofacial r. supraorbital r
trochanter r. contraction of the adductor muscles of the thigh elicited by a tap on the trochanter.
Trömner's 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.pronator r;
unconditioned r. an instinctive r. not dependent on previous learning or experience.
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).
urinary r. micturition r
utricular r.'s See statotonic r.'s.
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.
vertebra prominens r. pressure upon the last cervical vertebra of an animal, especially of one whose labyrinths have been destroyed and the vestibular nuclei isolated, causes relaxation or reduced tone of all four limbs.
vesical r. micturition r
vestibular ocular r. doll's eye signproprioceptive-oculocephalic r;
vestibulospinal r. the influence of vestibular stimulation on body posture.
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 r.'s, 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.
visceropannicular r. contraction of the panniculus carnosus muscle in the cat and certain other animals, in response to a stimulus applied to an abdominal viscus; the center for the r. is in the spinal cord, the afferent pathway is the splanchnic nerves.
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's 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.pharyngeal r. (2);
Weingrow's r. aponeurotic r
Westphal's pupillary r. eye-closure pupil reaction
white pupillary r. leukocoria
wink r. general term for r. closure of eyelids caused by any stimulus.eye-closure r;
withdrawal r. flexor r
wrist clonus r. sudden extension of the wrist induces a sustained clonic movement.


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