| lower motor neuron lesion | Injury to motor cells in the brainstem or spinal cord, or of the axons derived from them. (05 Mar 2000) |
|---|---|
| lower nephron nephrosis | An obsolete term for acute tubular necrosis. (05 Mar 2000) |
| 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, Richard | <person> English anatomist and physiologist, 1631-1691. See: Lower's ring, Lower's tubercle. (05 Mar 2000) |
| lower segment cesarian section | A Cesarian section in which the surgical incision (cut) is made in the lower segment of the uterus. (12 Dec 1998) |
| 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) |
| lower uterine segment | The inferior portion or isthmus of the uterus, the lower extremity of which joins with the cervical canal and, during pregnancy, expands to become the lower part of the uterine cavity. (05 Mar 2000) |
| lower uterine segment cesarean section | A cesarean section in which the uterus is entered in its lower segment by a transperitoneal approach. (05 Mar 2000) |
| alimentary tract | The passage leading from the mouth to the anus through the pharynx, oesophagus, stomach, and intestine. Synonym: alimentary canal, alimentary tract, digestive tube, tubus digestorius. (05 Mar 2000) |
| alimentary tract smear | A group of cytologic specimens containing material from the mouth (oral smear), oesophagus and stomach (gastric smear), duodenum (paraduodenal smear), and colon, obtained by specialised lavage techniques; used principally for the diagnosis of cancer of those areas. (05 Mar 2000) |
| anterior corticospinal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| anterior pyramidal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| anterior spinocerebellar tract | A bundle of fibres originating in the base of the posterior horn and zona intermedia throughout lumbosacral segments of the spinal cord, crossing to the opposite side and ascending in a peripheral position in the ventral half of the lateral funiculus. In its ascent through the rhombencephalon, the tract curves sharply dorsalward along the rostral border of the trigeminal motor nucleus, entering the cerebellum in a caudal direction over the dorsal surface of the superior cerebellar peduncle, and terminating as mossy fibres in the granular layer of the cortex of the cerebellar vermis. The bundle conveys proprioceptive and exteroceptive information largely from the opposite lower extremity. Synonym: tractus spinocerebellaris anterior, Gowers' column, Gowers' tract, ventral spinocerebellar tract. (05 Mar 2000) |