| segmental anaesthesia | Loss of sensation limited to an area supplied by one or more spinal nerve roots. (05 Mar 2000) |
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| segmental arteries of kidney | The branches of the renal artery that supply the anatomical segments of kidney. Usually five in number, they are end arteries and give off interlobar, arcuate and interlobular arteries in sequence. The latter send afferent arterioles to the glomeruli as well as branches to the kidney capsule. The segmental arteries of the kidney are identified as: anterior inferior (arteriae segmenti anterioris inferioris renis ); anterior superior (arteriae segmenti anterioris superioris renis ); inferior (arteriae segmenti inferioris renis ); posterior (arteriae segmenti posterioris renis ); and superior (arteriae segmenti superioris renis ). Synonym: arteriae renis, arteries of kidney. (05 Mar 2000) |
| segmental atelectasis | Partial collapse of one or more individual pulmonary segments. (05 Mar 2000) |
| segmental bronchus | One of the divisions of the lobar bronchus that supplies a bronchopulmonary segment. In the right lung there are commonly ten: in the superior lobe, the apical (B1) segmental bronchus, bronchus segmentalis apicalis; posterior (B2) segmental bronchus, bronchus segmentalis (BII) posterior; and anterior (B3) segmental bronchus, bronchus segmentalis (BIII) anterior; in the middle lobe, lateral (B4) segmental bronchus, bronchus segmentalis (BIV) lateralis; and medial (B5) segmental bronchus, bronchus segmentalis medialis (BV); in the inferior lobe, superior (B6) segmental bronchus, bronchus segmentalis superior (BVI), medial basal (B7) segmental bronchus, bronchus segmentalis basalis medialis (BVII); anterior basal (B8) segmental bronchus, bronchus segmentalis basalis anterior (BVIII); lateral basal (B9) segmental bronchus, bronchus segmentalis basalis lateralis (BIX); and posterior basal (B10) segmental bronchus, bronchus segmentalis basalis posterior (BX). In the left lung there are commonly nine: in the superior lobe, the apicoposterior (B1+2) segmental bronchus, bronchus segmentalis apicoposterior (BI+I); anterior (B3) segmental bronchus, bronchus segmentalis anterior (BIII); superior lingular (B4) segmental bronchus, bronchus lingularis superior (BIV); and inferior lingular (B5) segmental bronchus, bronchus lingularis inferior (BV); in the inferior lobe, superior (B6) segmental bronchus, bronchus segmentalis superior (BVI); medial basal (B7) segmental bronchus, bronchus segmentalis basalis medialis (cardiacus) (BVII), anterior basal (B8) segmental bronchus, bronchus segmentalis basalis anterior (BVIII); lateral basal (B9) segmental bronchus, bronchus segmentalis basalis lateralis (BIX); and posterior basal (B10) segmental bronchus, bronchus segmentalis basalis posterior (BX). Synonym: bronchus segmentalis. (05 Mar 2000) |
| segmental demyelinating polyneuropathy | A type of polyneuropathy in which almost solely the peripheral nerve myelin is affected; can be both familial (e.g., Charcot-Marie Tooth disease, type 1), or acquired (e.g., Guillain-Barre syndrome); on motor nerve conduction studies, manifested as conduction slowing or block. Synonym: segmental demyelinating polyneuropathy. (05 Mar 2000) |
| segmental fracture | A fracture in two parts of the same bone. Synonym: double fracture. (05 Mar 2000) |
| segmental glomerulonephritis | Glomerulonephritis affecting only part of a glomerulus or glomeruli. Synonym: local glomerulonephritis. (05 Mar 2000) |
| segmental glomerulosclerosis | <nephrology> A kidney disorder that results in fibrosis and scarring in the kidney glomerulus. The cause is unknown but some cases can result from reflux nephropathy. The clinical manifestation of this kidney disorder is nephrotic syndrome. Symptoms include weight gain, swelling, hypertension and foamy urine. High blood cholesterol and triglyceride levels are also seen with this disorder. Treatment has included the use of corticosteroids and immunosuppressives. Antihypertensive agents and diuretics may also be necessary. Over one-half will develop chronic renal failure within 10 years of diagnosis. (27 Sep 1997) |
| segmental mastectomy | <procedure, surgery> A surgical procedure in which only a portion of the breast is removed, including the cancer and the surrounding margin of healthy breast tissue. (09 Oct 1997) |
| segmental neuritis | Inflammation occurring at several points along the course of a nerve, segmental demyelinating neuropathy (05 Mar 2000) |
| segmental plate | In a young embryo, the thickened dorsal portion of the undifferentiated paraxial mesoderm which becomes metamerically divided to form the mesodermal somites. Synonym: segmental plate. (05 Mar 2000) |
| segmental sphincter | A sphincter of a segment of an organ, a tube, or a canal, and longer than an annular sphincter. (05 Mar 2000) |
| segmental tubule | An excretory tubule of the mesonephros. Synonym: segmental tubule. (05 Mar 2000) |
| segmental zone | In a young embryo, the thickened dorsal portion of the undifferentiated paraxial mesoderm which becomes metamerically divided to form the mesodermal somites. Synonym: segmental plate. (05 Mar 2000) |
| segmentation | <biology> Organisation of the body into repeating units called segments is a common feature of several phyla, for example arthropods and annelids, although the segments arise by very different mechanisms. Segmentation also occurs during embryonic development in vertebrates, for example partition of the mesoderm into somites and is a feature of early CNS development. See: rhombomeres, neuromeres. (18 Nov 1997) |
| valley segment | That portion of a stream network with similar morphologies and governing geomorphic processes identified by valley bottom and sideslope geomorphic characteristics. (05 Dec 1998) |
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| Ranvier's segment | The portion of a myelinated nerve fibre between two successive nodes. Synonym: interannular segment, internode, Ranvier's segment, segmentum internodale. (05 Mar 2000) |
| medial basal segment | Cardiac segment; medial basal segment of inferior lobe of right and left lung; can only be seen from medial and inferior surfaces since it does not reach lateral surface of lung. Synonym: segmentum basale mediale, segmentum cardiacum, cardiac segment. (05 Mar 2000) |
| medial segment | A delimited part or section of an organ or other structure which lies closer or closest to the midline than the other similar parts or sections. 1) segmentum mediale (hepar); the medial segment of the left lobe of the liver. 2) segmentum mediale (pulmo dexter); [S 5]; the medial segment of the middle lobe of the right lung. Synonym: segmentum mediale. (05 Mar 2000) |
| cesarian section, lower segment | A Cesarian section in which the surgical incision (cut) is made in the lower segment of the uterus. (12 Dec 1998) |
| mesoblastic segment | 1. <zoology> One of the actual or ideal serial segments of which an animal, especially. An articulate or vertebrate, is is composed; somatome; metamere. Somitic. 2. <embryology> Segmentally arranged blocks of mesoderm lying on either side of the notochord and neural tube during development of the vertebrate embryo. Somites are formed sequentially, starting at the head. Each somite will give rise to muscle from the myotome region), spinal column (from the sclerotome) and dermis (from dermatome). (04 Mar 1998) |
| rod outer segment | <ophthalmology, physiology> Major photoreceptor cell of vertebrate retina (about 125 million in a human eye). Columnar cells (about 40m long, 1m diameter) having three distinct regions: a region adjacent to and synapsed with, the neural layer of the retina contains the nucleus and other cytoplasmic organelles, below this is the inner segment, rich in mitochondria, that is connected through a thin neck (in which is located a ciliary body) to the outer segment. The outer segment largely consists of a stack of discs membrane infoldings that are incompletely separated in cones) that are continually replenished near the inner segment and that are shed from the distal end and phagocytosed by the pigmented epithelium. The membranes of the discs are rich in rhodopsin, the pigment that absorbs light. (03 Jul 1999) |
| RST segment | The part of the electrocardiogram between the QRS complex and the T wave. Virtually never distinct in normal hearts in which it forms the initial limb of the T wave without an agreed endpoint. (05 Mar 2000) |
| posterior basal segment | Posterior basal segment of inferior lobe of right and left lungs; lies adjacent to vertebral column below superior segment. Synonym: segmentum basale posterius. (05 Mar 2000) |
| posterior segment | A delimited part or section of an organ or other structure which lies in back of or dorsal to the other similar parts or sections; 1) segmentum posterius (hepar); the posterior segment of the right lobe of the liver; 2) segmentum posterius (pulmo dexter); [S 2]; the posterior segment of the superior lobe of the right lung; 3) segmentum posterius (ren); the posterior segment of the kidney; 4) camera vitrea bulbi; vitreous camera; vitreous chamber of eye; the posterior intraocular segment of the eyeball occupied by the vitreous which lies behind the aqueous-filled anterior segment and is separated from it by the lens and zonule. Synonym: segmentum posterius. (05 Mar 2000) |
| posterior segment of eyeball | The large space between the lens and the retina; it is filled with the vitreous body. Synonym: camera vitrea bulbi, vitreous camera, vitreous chamber of eye. (05 Mar 2000) |
| P-R segment | That part of the electrocardiographic curve between the end of the P wave and the beginning of the QRS complex. (05 Mar 2000) |
| section, lower segment cesarian | A Cesarian section in which the surgical incision (cut) is made in the lower segment of the uterus. (12 Dec 1998) |
| neural segment | Alternate swellings and constrictions seen along the neuraxis at early stages of neural tube development, thought to be evidence of intrinsic segmentation in the CNS. Neuromeres or segments in the hindbrain region are called rhombomeres and have been shown to be lineage restriction units, each constructing a defined piece of hindbrain. (18 Nov 1997) |
| S-T segment | That part of the electrocardiographic tracing immediately following the QRS complex and merging into the T wave. (05 Mar 2000) |