| twixt-brain | <anatomy> The thalamencephalon. Source: Websters Dictionary (01 Mar 1998) |
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| lateral fossa of brain | The deep depression of the basal surface of the forebrain that corresponds in position to the anterior perforated substance. Bounded medially by the optic tract and rostrally by the orbital surface of the frontal lobe, it extends laterally around the overhanging pole of the temporal lobe into the Sylvian fissure (sulcus lateralis). Synonym: fossa lateralis cerebri, fossa of Sylvius, lateral fossa of brain, vallecula sylvii. (05 Mar 2000) |
| 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) |
| anal reflex | Contraction of the internal sphincter gripping the finger passed into the rectum. (05 Mar 2000) |
| ankle 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) |
| aortic reflex | 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. Synonym: aortic reflex, depressor reflex. (05 Mar 2000) |
| aponeurotic reflex | 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 reflex Also called Guillain-Barre, Weingrow's, or sole tap reflex. Synonym: Guillain-Barre reflex, sole tap reflex, Weingrow's reflex. (05 Mar 2000) |