reflex /re·flex/ (re´fleks) a reflected action or movement; the sum total of any particular automatic response mediated by the nervous system.
ciliospinal reflex
abdominal reflexes contractions of the abdominal muscles on stimulation of the abdominal skin.
accommodation reflex the coordinated changes that occur when the eye adapts itself to near vision; constriction of the pupil, convergence of the eyes, and increased convexity of the lens.
Achilles tendon reflex triceps surae r.
acoustic reflex contraction of the stapedius muscle in response to intense sound.
anal reflex contraction of the anal sphincter on irritation of the anal skin.
ankle reflex triceps surae r.
auditory reflex any reflex caused by stimulation of the vestibulocochlear nerve, especially momentary closure of both eyes produced by a sudden sound.
Babinski's reflex dorsiflexion of the big toe on stimulation of the sole, occurring in lesions of the pyramidal tract, although a normal reflex in infants.
Babkin reflex pressure by the examiner's thumbs on the palms of both hands of the infant results in opening of the infant's mouth.
baroreceptor reflex the reflex response to stimulation of baroreceptors of the carotid sinus and aortic arch, regulating blood pressure by controlling heart rate, strength of heart contractions, and diameter of blood vessels.
Bezold reflex , Bezold-Jarisch reflex reflex bradycardia and hypotension resulting from stimulation of cardiac chemoreceptors by antihypertensive alkaloids and similar substances.
biceps reflex contraction of the biceps muscle when its tendon is tapped.
Brain's reflex extension of a hemiplegic flexed arm on assumption of a quadrupedal posture.
brain stem reflexes those regulated at the level of the brain stem, such as pupillary, pharyngeal, and cough reflexes, and the control of respiration; their absence is one criterion of brain death.
bulbospongiosus reflex contraction of the bulbospongiosus muscle in response to a tap on the dorsum of the penis.
carotid sinus reflex slowing of the heart beat on pressure on the carotid artery at the level of the cricoid cartilage.
Chaddock's reflex in lesions of the pyramidal tract, stimulation below the external malleolus causes extension of the great toe.
chain reflex a series of reflexes, each serving as a stimulus to the next one, representing a complete activity.
ciliary reflex the movement of the pupil in accommodation.
ciliospinal reflex dilation of the ipsilateral pupil on painful stimulation of the skin at the side of the neck.
closed loop reflex a reflex, such as a stretch reflex, in which the stimulus decreases when it receives feedback from the response mechanism.
conditioned reflex see under response.
conjunctival reflex closure of the eyelid when the conjunctiva is touched.
corneal reflex closure of the lids on irritation of the cornea.
cough reflex the events initiated by the sensitivity of the lining of the airways and mediated by the medulla as a consequence of impulses transmitted by the vagus nerve, resulting in coughing.
cremasteric reflex stimulation of the skin on the front and inner thigh retracts the testis on the same side.
deep reflex tendon r.
digital reflex Hoffmann's sign (2).
diving reflex a reflex involving cardiovascular and metabolic adaptations to conserve oxygen occurring in animals during diving into water; observed in reptiles, birds, and mammals, including humans.
elbow reflex triceps r.
embrace reflex Moro's r.
finger-thumb reflex opposition and adduction of the thumb combined with flexion at the metacarpophalangeal joint and extension at the interphalangeal joint on downward pressure of the index finger.
gag reflex pharyngeal r.
gastrocolic reflex increase in intestinal peristalsis after food enters the empty stomach.
gastroileal reflex increase in ileal motility and opening of the ileocecal valve when food enters the empty stomach.
grasp reflex flexion or clenching of the fingers or toes on stimulation of the palm or sole, normal only in infancy.
Hering-Breuer reflex the reflex that limits excessive expansion and contraction of the chest during respiration prior to sending impulses to the brain via the vagus nerve.
Hoffmann's reflex see under sign (2).
hypogastric reflex contraction of the muscles of the lower abdomen on stroking the skin on the inner surface of the thigh.
jaw reflex , jaw jerk reflex closure of the mouth caused by a downward blow on the passively hanging chin; rarely seen in health but very noticeable in corticospinal tract lesions.
knee jerk reflex patellar r.
light reflex
1. cone of light.
2. contraction of the pupil when light falls on the eye.
3. a spot of light seen reflected from the retina with the retinoscopic mirror.
Magnus and de Kleijn neck reflexes extension of both ipsilateral limbs, or one, or part of a limb, increase of tonus on the side to which the chin is turned when the head is rotated to the side, and flexion with loss of tonus on the side to which the occiput points; sign of decerebrate rigidity except in infants.
Mayer's reflex finger-thumb r.
Mendel-Bekhterev reflex dorsal flexion of the second to fifth toes on percussion of the dorsum of the foot; in certain organic nervous disorders, plantar flexion occurs.
micturition reflex any of the reflexes necessary for effortless urination and subconscious maintenance of continence.
Moro's reflex flexion of an infant's thighs and knees, fanning and then clenching of fingers, with arms first thrown outward and then brought together as though embracing something; produced by a sudden stimulus and seen normally in the newborn.
myotatic reflex stretch r.
neck reflexes reflex adjustments in trunk posture and limb position caused by stimulation of proprioceptors in the neck joints and muscles when the head is turned, tending to maintain a constant orientation between the head and body.
neck righting reflex rotation of the trunk in the direction in which the head of the supine infant is turned; this reflex is absent or decreased in infants with spasticity.
nociceptive reflexes reflexes initiated by painful stimuli.
oculocardiac reflex a slowing of the rhythm of the heart following compression of the eyes; slowing of from 5 to 13 beats per minute is normal.
open loop reflex a reflex in which the stimulus causes activity that it does not further control and from which it does not receive feedback.
Oppenheim reflex dorsiflexion of the big toe on stroking downward along the medial side of the tibia, seen in pyramidal tract disease.
orbicularis oculi reflex normal contraction of the orbicularis oculi muscle, with resultant closing of the eye, on percussion at the outer aspect of the supraorbital ridge, over the glabella, or around the margin of the orbit.
orbicularis pupillary reflex unilateral contraction of the pupil followed by dilatation after closure or attempted closure of eyelids that are forcibly held apart.
palatal reflex , palatine reflex stimulation of the palate causes swallowing.
patellar reflex contraction of the quadriceps and extension of the leg when the patellar ligament is tapped.
peristaltic reflex when a portion of the intestine is distended or irritated, the area just proximal contracts and the area just distal relaxes.
pharyngeal reflex contraction of the pharyngeal constrictor muscle elicited by touching the back of the pharynx.
pilomotor reflex the production of goose flesh on stroking the skin.
placing reflex flexion followed by extension of the leg when the infant is held erect and the dorsum of the foot is drawn along the under edge of a table top; it is obtainable in the normal infant up to the age of six weeks.
plantar reflex irritation of the sole contracts the toes.
proprioceptive reflex one initiated by a stimulus to a proprioceptor.
pupillary reflex
1. contraction of the pupil on exposure of the retina to light.
2. any reflex involving the iris, resulting in change in the size of the pupil, occurring in response to various stimuli, e.g., change in illumination or point of fixation, sudden loud noise, or emotional stimulation.
quadriceps reflex patellar r.
quadrupedal extensor reflex Brain's r.
red reflex a luminous red appearance seen upon the retina in retinoscopy.
righting reflex the ability to assume an optimal position when there has been a departure from it.
Rossolimo's reflex in pyramidal tract lesions, plantar flexion of the toes on tapping their plantar surface.
scratch reflex a spinal reflex by which an itch or other irritation of the skin causes a nearby body part to move over and briskly rub the affected area.
spinal reflex any reflex action mediated through a center of the spinal cord.
startle reflex Moro's r.
stepping reflex movements of progression elicited when the infant is held upright and inclined forward with the soles of the feet touching a flat surface.
stretch reflex reflex contraction of a muscle in response to passive longitudinal stretching.
sucking reflex sucking movements of the lips of an infant elicited by touching the lips or the skin near the mouth.
superficial reflex any withdrawal reflex elicited by noxious or tactile stimulation of the skin, cornea, or mucous membrane, including the corneal reflex, pharyngeal reflex, cremasteric reflex, etc.
swallowing reflex palatal r.
tendon reflex one elicited by a sharp tap on the appropriate tendon or muscle to induce brief stretch of the muscle, followed by contraction.
tonic neck reflex extensions of the arm and sometimes of the leg on the side to which the head is forcibly turned, with flexion of the contralateral limbs; seen normally in the newborn.
triceps reflex contraction of the belly of the triceps muscle and slight extension of the arm when the tendon of the muscle is tapped directly, with the arm flexed and fully supported and relaxed.
triceps surae reflex plantar flexion caused by a twitchlike contraction of the triceps surae muscle, elicited by a tap on the Achilles tendon, preferably while the patient kneels on a bed or chair, the feet hanging free over the edge. 
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Triceps surae reflex.
vestibular reflexes the reflexes for maintaining the position of the eyes and body in relation to changes in orientation of the head.
vestibuloocular reflex nystagmus or deviation of the eyes in response to stimulation of the vestibular system by angular acceleration or deceleration or when the caloric test is performed.
withdrawal reflex a nociceptive reflex in which a body part is quickly moved away from a painful stimulus.
| ciliospinal reflex n. |
ciliospinal reflex
Etymology: L, cilia + spina, backbone, reflectere, to bend back
a normal brainstem reflex initiated by scratching or pinching the skin of the neck or face, causing dilatation of the pupil. Also called pupillary skin reflex.
ciliospinal
pertaining to the ciliary body and the spinal cord.
ciliospinal reflex
dilatation of the pupil when the skin of the neck is stimulated painfully.
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