| tonic convulsion | A convulsion in which muscle contraction is sustained. Synonym: tetanic convulsion, tonic seizure. (05 Mar 2000) |
|---|---|
| tonic epilepsy | An attack in which the body is rigid. (05 Mar 2000) |
| tonic pupil | Usually a unilateral abnormality of the eye characterised by slow pupillary constriction to light and in which there is a delayed reaction to changes in accommodation and convergence. The affected pupil is usually larger. (12 Dec 1998) |
| tonic seizure | Sustained contractures of skeletal muscle as occur during convulsions. Synonym: tonic convulsion. (05 Mar 2000) |
| tonic spasm | A continuous involuntary muscular contraction. (05 Mar 2000) |
| epilepsy, tonic-clonic | Primary generalised epileptic seizures, starting without warning, characterised by loss of consciousness, tonic contraction of muscles, loss of postural control, and production of a cry by the forced expiration of air due to contraction of the respiratory muscles. The individual then falls to the floor and remains rigid for a few seconds, after which a series of rhythmic contractions occur in all four limbs. This clonic phase can last for a variable period, ending only upon muscle relaxation. Upon recovery, there is a gradual return to consciousness, disorientation, amnesia for the seizure, sometimes retrograde amnesia as well, headache, and drowsiness. The individual may not return to baseline functioning for days. (12 Dec 1998) |
| abdominocardiac reflex | Mechanical stimulation (usually distention) of abdominal viscera causing changes (usually a slowing) in the heart rate or the occurrence of extrasystoles. (05 Mar 2000) |
| Abrams' heart reflex | A contraction of the myocardium when the skin of the precordial region is irritated. (05 Mar 2000) |
| accommodation reflex | Increased convexity of the lens, due to contraction of the ciliary muscle and relaxation of the suspensory ligament, to maintain a distinct retinal image. (05 Mar 2000) |
| Achilles reflex | A contraction of the calf muscles when the tendo calcaneus is sharply struck. Synonym: ankle jerk, ankle reflex, tendo Achillis reflex, triceps surae reflex. (05 Mar 2000) |
| acousticopalpebral reflex | A form of the wink reflex 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. Synonym: acousticopalpebral reflex, auropalpebral reflex, cochleo-orbicular reflex, startle reflex. (05 Mar 2000) |
| acquired reflex | A reflex that is gradually developed by training and association through the frequent repetition of a definite stimulus. See: conditioning. Synonym: acquired reflex, behaviour reflex, trained reflex. (05 Mar 2000) |
| acromial reflex | Contraction of the biceps muscle caused by a tap on the acromion or the coracoid process. (05 Mar 2000) |
| acute reflex bone atrophy | Atrophy of bones, commonly of the carpal or tarsal bones, following a slight injury such as a sprain. See: causalgia, reflex sympathetic dystrophy. Synonym: acute reflex bone atrophy, posttraumatic osteoporosis, Sudeck's syndrome. Origin: L. English sweat (05 Mar 2000) |
| adductor reflex | Contraction of the adductors of the thigh caused by tapping the tendon of the adductor magnus muscle while the thigh is abducted. (05 Mar 2000) |