| upper motor neuron lesion | Injury to cerebral descending (corticonuclear) fibres above the brainstem or spinal motor nerve nucleus. Synonym: upper motor neuron lesion. (05 Mar 2000) |
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| upper nodal extrasystole | An obsolete term for a nodal extrasystole supposed to arise from the upper part of the A-V node; recognised in the electrocardiogram by a retrograde P wave preceding the QRS complex by an abnormally short P-R interval. (05 Mar 2000) |
| upper respiratory infection | Any number of viral or bacterial infections that includes infections of the throat, nasopharynx, sinuses, larynx, trachea or bronchi. (27 Sep 1997) |
| upper respiratory tract | The nasopharynx, oral cavity, and throat. (09 Oct 1997) |
| upper subscapular nerve | Two branches of the posterior cord of the brachial plexus, an upper and lower, supplying the subscapularis muscle; the lower subscapular nerve also supplies the teres major muscle. Synonym: nervi subscapulares. (05 Mar 2000) |
| upper thoracic splanchnic nerves | Part of the cardiopulmonary splanchnic nerves from the second to fifth segments of the thoracic sympathetic trunk that pass medially and anteriorly to enter the cardiac plexus; they convey postsynaptic sympathetic fibres to, and visceral afferent (pain) fibres from, the heart. Synonym: nervi cardiaci thoracici, upper thoracic splanchnic nerves. (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) |
| 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) |
| artery of anterior inferior segment of kidney | Origin, anterior branch of renal. See: segmental arteries of kidney. Synonym: arteria segmenti anterioris inferioris renis, artery of anterior {inferior segment of kidney}. (05 Mar 2000) |
| artery of anterior superior segment of kidney | Origin, anterior branch of renal. See: segmental arteries of kidney. Synonym: arteria segmenti anterioris superioris renis, artery of anterior {superior segment of kidney}. (05 Mar 2000) |