| UA | absorption unsharpness; ultra-audible; ultrasonic arteriography; umbilical artery; unauthorized abse... |
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| UE | uncertain etiology; under elbow; uninvolved epidermis; upper esophagus; upper extremity |
| URI | uniform resource identifier; upper respiratory illness; upper respiratory infection |
| US | screen unsharpness ultrasonic, ultrasound; ultrasonography; unconditioned stimulus; unique sequence;... |
| LES | Lower Esophageal Sphincter; 하부 식도 괄약근 |
| upper lobe of lung | The lobe of the right lung that lies above the oblique and horizontal fissures and includes the apical, posterior and anterior bronchopulmonary segments; in the left lung, the lobe lies above the oblique fissure and contains the apicoposterior, anterior, superior lingular and inferior lingular segments. Synonym: lobus superior pulmonis, upper lobe of lung. (05 Mar 2000) |
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| upper/lower lobe predominance | <radiology> Upper lobe, usually site of greatest disease due to poorer clearance, bronchogenic carcinoma, pneumoconioses, histiocytosis X, sarcoidosis, ankylosing spondylitis, lower lobe, scleroderma (12 Dec 1998) |
| upper motor neuron | Clinical term indicating those neuron's of the motor cortex that contribute to the formation of the pyramidal or corticospinal and corticobulbar tracts, as distinguished from the lower motor neuron's innervating the skeletal muscles. Although not motor neuron's in the strict sense, these cortical neuron's became colloquially classified as motor neuron's because their stimulation produces movement and their destruction causes severe disorders of movement. See: motor neuron, motor cortex. (05 Mar 2000) |
| 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) |
| 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) |
| upper uterine segment | The main portion of the body of the gravid uterus, the contraction of which furnishes the chief force of expulsion in labour. (05 Mar 2000) |
| anal sphincter | See: external anal sphincter, internal anal sphincter. (05 Mar 2000) |
| anatomical sphincter | An accumulation of muscular circular fibres or specially arranged oblique fibres the function of which is to reduce partially or totally the lumen of a tube, the orifice of an organ, or the cavity of a viscus; the closing component of a pylorus. (05 Mar 2000) |
| annular sphincter | A short thickening of circular muscular fibres, similar to a ring; a ring-shaped sphincter as opposed to a segmental sphincter. (05 Mar 2000) |
| antral sphincter | Angular sphincter, thickening of the circular muscular layer forming a proposed intermediate sphincter at the level of the angular notch of the stomach. While the thickening of the circular muscle may indicate the commencement of the pyloric antrum, true functional sphincteric activity distinct from the other peristaltic contractions of the stomach is not observed although some of these may in fact temporarily close off the antrum from the remainder of the stomach lumen. Synonym: antral sphincter, midgastric transverse sphincter, sphincter antri, sphincter intermedius, sphincter of antrum, sphincter of gastric antrum. (05 Mar 2000) |
| artificial sphincter | A sphincter produced by surgical procedures to reduce speed of flow in the digestive system or to maintain continence of the intestine. (05 Mar 2000) |