| lower nodal extrasystole | An obsolete term for a nodal extrasystole supposed to arise from the lower part of the A-V node, recognised in the electrocardiogram by the retrograde P wave that follows the QRS complex. (05 Mar 2000) |
|---|---|
| lower oesophageal sphincter | <anatomy> A muscular sphincter located at the junction of the oesophagus and the stomach. On closure the lower oesophageal sphincter prevents the back wash (reflux) of stomach acid into the oesophagus where it may damage the mucosa. See: gastrooesophageal reflux disease. (16 Mar 1998) |
| lower respiratory tract | <anatomy> The trachea, bronchi, and lungs. (09 Oct 1997) |
| lower respiratory tract smear | A group of cytologic specimens containing material from the lower respiratory tract and consisting mainly of sputum (spontaneous, induced) and material obtained at bronchoscopy (aspirated, lavaged, brushed); used for cytologic study of cancer and other diseases of the lungs. Synonym: bronchoscopic smear, sputum smear. (05 Mar 2000) |
| Lower, Richard | <person> English anatomist and physiologist, 1631-1691. See: Lower's ring, Lower's tubercle. (05 Mar 2000) |
| Lower's ring | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
| Lower's tubercle | The slight projection on the wall of the right atrium between the orifices of the venae cavae. Synonym: tuberculum intervenosum, Lower's tubercle. (05 Mar 2000) |
| anterior basal segment | Anterior basal segment of inferior lobe of right and left lung; lies between middle lobe and diaphragm. Synonym: segmentum basale anterius. (05 Mar 2000) |
| anterior eye segment | That part of the eyeball anterior to the lens. (12 Dec 1998) |
| anterior inferior segment | Anterior inferior segment of kidney. Synonym: segmentum anterius inferius. (05 Mar 2000) |
| anterior ocular segment | That portion of the eye comprising the cornea, iris, lens, and their associated chambers and adnexa. (05 Mar 2000) |
| anterior segment | A delimited part or section of an organ or other structure which lies in front of or ventral to the other similar parts or sections. 1) segmentum anterius (hepar); the anterior segment of the right lobe of the liver. 2) segmentum anterius (pulmo dexter et sinister); [S 3]; the anterior segment of the superior lobe of the right and left lungs. 3) anterior segment of the eye; the intraocular segment of the eyeball occupied by the aqueous which lies in front of, and is separated from the vitreous-filled posterior segment by, the lens and zonule; it is subdivided by the iris into anterior and posterior chambers. Synonym: segmentum anterius. (05 Mar 2000) |
| anterior superior segment | Anterior superior segment of kidney. Synonym: segmentum anterius superius. (05 Mar 2000) |
| apical segment | Apical segment of the superior lobe of the right lung, apical segment of the inferior lobe of the right and left lungs. Synonym: segmentum superius. Synonym: segmentum superius, segmentum apicale, superior segment. (05 Mar 2000) |
| apicoposterior segment | Apicoposterior segment of superior lobe of left lung, composed of two segments and wedged between the anterior segment of the upper lobe and the oblique fissure. Synonym: segmentum apicoposterius. (05 Mar 2000) |