| third sound | Occurs in early diastole and corresponds with the end of the first phase of rapid ventricular filling; normal in children and younger people but abnormal in others. Synonym: third sound. (05 Mar 2000) |
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| third stage of labour | The part of labour from the birth of the baby until the placenta (afterbirth) and foetal membranes are delivered. The third stage of labour is also called the placental stage. (12 Dec 1998) |
| third temporal convolution | A sagittal convolution on the inferolateral border of the temporal lobe of the cerebrum, separated from the middle temporal gyrus by the inferior temporal sulcus. On the inferior surface of the temporal lobe it is separated from the medial occipitotemporal gyrus by the occipitotemporal sulcus. It includes the lateral occipitotemporal gyrus. Synonym: gyrus temporalis inferior, inferior temporal convolution, third temporal convolution. (05 Mar 2000) |
| third tonsil | A collection of more or less closely aggregated lymphoid nodules on the posterior wall and roof of the nasopharynx, the hypertrophy of which constitutes the morbid condition called adenoids. Synonym: tonsilla pharyngealis, tonsilla adenoidea, Luschka's gland, Luschka's tonsil, third tonsil. (05 Mar 2000) |
| third trochanter | An occasional process at the proximal end of the lateral lip of the linea aspera of the femur, about on a level with the lesser trochanter, giving insertion to the greater part of the gluteus maximus muscle. See: gluteal tuberosity. (05 Mar 2000) |
| third ventricle | A narrow, vertically oriented, irregularly quadrilateral cavity in the midplane, extending from the lamina terminalis to the rostral opening of the mesencephalic aqueduct. This ventricle communicates at its rostrodorsal corner with each of the two lateral ventricles through the left and right interventricular foramen of Monro. Its narrow roof is formed by the tela choroidea which is attached on either side to the tenia thalami; its lateral wall by the medial surface of the thalamus and, below the hypothalamic sulcus, by the hypothalamus which also forms its floor. In lateral profile, the third ventricle exhibits a number of recesses: in its floor, from before backward, 1) the preoptic recess in the acute angle between the base of the lamina terminalis and the dorsum of the optic chiasm, 2) the infundibular recess extending ventrally into the infundibulum but (in humans) not into the hypophysial stalk, and 3) the mamillary or inframamillary recess caused by the protrusion of the mamillary bodies into the ventricle. From its dorsocaudal corner, the pineal recess extends caudally into the pineal stalk. Synonym: ventriculus tertius, diacele, ventricle of diencephalon. (05 Mar 2000) |
| third ventriculostomy | An operation to establish an opening from the third ventricle to the prechiasmal and interpeduncular cisterns (Stookey-Scarff operation) or from the third ventricle to the interpeduncular cistern (Dandy operation). (05 Mar 2000) |
| acrylic resin tooth | A tooth made of acrylic resin. (05 Mar 2000) |
| ankylosed tooth | <dentistry> Bony union of the radicular surface of a tooth to the surrounding alveolar bone in an area of previous partial root resorption. Extracapsular ankylosis, stiffness of a joint due to induration or heterotopic ossification of the surrounding tissues. Synonym: spurious ankylosis. (05 Mar 2000) |
| apex of cusp of tooth | The tip of the peaklike projections from the crown of a tooth. Synonym: apex cuspidis dentis. (05 Mar 2000) |
| apical foramen of tooth | The opening at the apex of the root of a tooth that gives passage to the nerve and blood vessels. Synonym: foramen apicis dentis, apical dental foramen, root foramen. (05 Mar 2000) |
| baby tooth | 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) |
| bicuspid tooth | A tooth usually having two tubercles or cusps on the grinding surface and a flattened root, single in the lower jaw and upper second premolar, and furrowed in the upper first premolar. There are four premolars in each jaw, two on either side between the canine and the molars; there are no premolars in the deciduous dentition. Synonym: dens premolaris, bicuspid tooth, dens bicuspidus. (05 Mar 2000) |
| buck tooth | An anterior tooth in labioversion. (05 Mar 2000) |
| canine tooth | <dentistry> A tooth having a crown of thick conical shape and a long, slightly flattened conical root; there are two canine teeth in each jaw, one on either side adjacent to the distal surface of the lateral incisors, in both the deciduous and the permanent dentition. Synonym: dens caninus, canine, cuspid tooth, cuspidate tooth, cuspid, dens angularis, dens cuspidatus, eye tooth. (05 Mar 2000) |