| trefoil tendon | A three-lobed fibrous sheet occupying the centre of the diaphragm. Synonym: centrum tendineum diaphragmatis, trefoil tendon. Central tendon of perineum, the fibromuscular mass between the anal canal and the urogenital diaphragm in the median plane; midline episiotomies extend into this structure. Synonym: centrum tendineum perinei, perineal body, Savage's perineal body. (05 Mar 2000) |
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| Zinn's tendon | A fibrous ring that surrounds the optic canal and the medial part of the superior orbital fissure; it gives origin to the four rectus muscles of the eye and is partially fused with the sheath of the optic nerve. Synonym: annulus tendineus communis, Zinn's ligament, Zinn's ring, Zinn's tendon. (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) |