| transverse disk | One of the dark transverse bands seen on examining a striated muscular fibre under the microscope. (05 Mar 2000) |
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| triangular disk of wrist | The disk that holds together the distal ends of the radius and ulna; it is attached by its apex to a depression between the styloid process and distal surface of the head of the ulna, and by its base to the ridge separating the ulnar notch from the carpal surface of the radius. Synonym: discus articularis radioulnaris, radioulnar disk, radioulnar articular disk, triangular cartilage, triangular disk of wrist, triquetrous cartilage. (05 Mar 2000) |
| Z disk | <cell biology> The line formed where actin filaments attach between two sarcomeres. (11 May 1997) |
| Lagrange disk | <microscopy> The exit pupil of the microscope, also called exit pupil, eyepoint and Ramsden circle or disk. (05 Aug 1998) |
| lumbar disk removal | A surgical procedure which is designed to relieve pressure on the spinal cord or nerve root that is being caused by a slipped or herniated disk in the lumbar spine. This procedure is also used in the treatment of spinal stenosis. This procedure includes removal of a portion of the bone comprising a vertebra. Recovery is generally 7-10 days. An alternative to this is a micro-disc surgery. (27 Sep 1997) |
| abnormal cleavage of cardiac valve | Congenital malformation of a valve leaflet with a defect extending from the free margin. (05 Mar 2000) |
| Amussat's valve | A series of crescentic folds of mucous membrane in the upper part of the cystic duct, arranged in a somewhat spiral manner. Synonym: plica spiralis ductus cystici, Amussat's valve, Heister's valve, spiral valve of cystic duct, valvula spiralis. (05 Mar 2000) |
| anterior cusp of atrioventricular valve | The anterior leaflet or valvule of either the tricuspid or mitral valves. Synonym: cuspis anterior valvae atrioventricularis dextrae/sinistrae. (05 Mar 2000) |
| anterior urethral valve | A crescentic horizontal fold in the proximal spongy urethra. (05 Mar 2000) |
| aortic valve | The heart valve that divides the left ventricle and the aorta. The aortic valve opens during left ventricular contraction and then closes to prohibit the backwash of oxygenated blood from the aorta into the ventricle. The aortic valve has 3 valve cusps. (27 Sep 1997) |
| aortic valve insufficiency | Backflow of blood from the aorta into the left ventricle, owing to imperfect functioning of the aortic semilunar valve. (12 Dec 1998) |
| aortic valve prolapse | The downward displacement of the cuspal material (misalignment of the cusps) below a line joining points of attachment of the aortic valve leaflets. The prolapsed cusp may occlude the ventricular septal defect during ventricular diastole. (12 Dec 1998) |
| aortic valve stenosis | Narrowing of the orifice of the aortic valve or of the supravalular or subvalvular regions. (12 Dec 1998) |
| artificial heart valve | <cardiology> A synthetic or porcine (pigskin) valve surgically placed into the heart to replace a defective or malfunctioning valve. The aortic and mitral valves are the most frequently replaced with artificial valves. (27 Sep 1997) |
| ball valve | Any of a variety of prosthetic cardiac valve's comprised of a ball within a retaining cage affixed to the orifice; when appropriately sized, used in aortic, mitral, or tricuspid position. (05 Mar 2000) |