| first dentition | A tooth of the first set of teeth, comprising 20 in all, that erupts between the mean ages of 6 and 28 months of life. Synonym: dens deciduus, baby tooth, deciduous dentition, dens lacteus, first dentition, milk tooth, primary dentition, primary tooth, temporary tooth. (05 Mar 2000) |
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| burns, third degree | In third degree burns the damage has progressed to the point of skin death. The skin is white and without sensation. (12 Dec 1998) |
| choroid plexus of third ventricle | The double row of vascular projections from the undersurface of the tela choroidea where it roofs over the third ventricle. Synonym: plexus choroideus ventriculi tertii. (05 Mar 2000) |
| choroid tela of third ventricle | A double fold of pia mater, enclosing subarachnoid trabeculae, between the fornix above and the epithelial roof of the third ventricle and the thalami below; at each lateral margin is a vascular fringe projecting into the choroidal fissure of the lateral ventricle; on its undersurface are several small vascular projections filling the folds of the ependymal roof of the third ventricle. Synonym: tela choroidea ventriculi tertii, tela choroidea superior, triangular lamella, velum interpositum, velum triangulare. (05 Mar 2000) |
| molar, third | The aftermost permanent tooth on each side in the maxilla and mandible. (12 Dec 1998) |
| pregnancy trimester, third | Period of pregnancy from the beginning of the 29th through the 42nd completed week (197 to 294 days) of gestation. (12 Dec 1998) |
| healing by third intention | The slow filling of a wound cavity or ulcer by granulations, with subsequent cicatrization. (05 Mar 2000) |
| sphincter of third portion of duodenum | A physiological sphincter supposedly located at the horizontal (inferior) portion of the duodenum. (05 Mar 2000) |
| styloid process of third metacarpal bone | A pointed projection from the dorsolateral angle of the base of the third metacarpal bone; it sometimes exists as a separate ossicle. Synonym: processus styloideus ossis metacarpalis III. (05 Mar 2000) |
| syndrome, third and fourth pharyngeal pouch | See syndrome, digeorge. (12 Dec 1998) |
| third | 1. Next after the second; coming after two others; the ordinal of three; as, the thirdhour in the day. "The third night." 2. Constituting or being one of three equal parts into which anything is divided; as, the third part of a day. Third estate. In England, the commons, or the commonalty, who are represented in Parliament by the House of Commons. In France, the tiers etat. See Tiers etat. Third order See Third. Origin: OE. Thirde, AS. Ridda, fr. Ri, reo, three; akin to D. Derde third, G. Dritte, Icel. Rii, Goth. Ridja, L. Tertius, Gr, Skr. Ttiya. See Three, and cf. Riding a jurisdiction, Tierce. Source: Websters Dictionary (01 Mar 1998) |
| third and fourth pharyngeal pouch syndrome | <syndrome> Also called the digeorge syndrome (dgs), this disorder is characterised by (1) low blood calcium levels (hypocalcaemia) due to underdevelopment (hypoplasia) of the parathyroid glands which control calcium; (2) underdevelopment (hypoplasia) of the thymus, an organ behind the breastbone in which lymphocytes mature and multiply; and (3) defects of the heart involving the outflow tracts more than from the heart. most cases of dgs are due to a microdeletion in chromosome band 22q11.2. A small number of cases have defects in other chromosomes, notably 10p13. Named after the american paediatric endocrinologist angelo digeorge. Another name for dgs is hypoplasia of the thymus and parathyroids. (12 Dec 1998) |
| third corpuscle | <haematology> A discoid cell (3m diameter) found in large numbers in blood, important for blood coagulation and for haemostasis by repairing breaches (small breaks) in the walls of blood vessels. Platelet _ granules contain lysosomal enzymes, dense granules contain ADP (a potent platelet aggregating factor) and serotonin (a vasoactive amine). They also release platelet-derived growth factor which presumably contributes to later repair processes by stimulating fibroblast proliferation. Synonym: thrombocytes. (09 Oct 1997) |
| third cranial nerve | <anatomy, nerve> Responsible for motor enervation of upper eyelid muscle, extraocular muscle and pupillary muscle. Lesions of the oculomotor nerve results in ptosis (dropping eyelid), deviation of the eyeball outward, double vision and a dilated pupil. (27 Sep 1997) |
| third cuneiform bone | A bone of the distal row of the tarsus; it articulates with the intermediate cuneiform, cuboid, navicular, and second, third, and fourth metatarsal bones. Synonym: os cuneiforme laterale, third cuneiform bone, wedge bone. (05 Mar 2000) |