| 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) |
| acute lower GI haemorrhage | <gastroenterology> Typical presentation: Sudden onset of brisk rectal bleeding without blood in gastric aspirate Diagnostic considerations: diverticulosis, angiodysplasia, ischemic colitis, inflammatory bowel disease (rarely), polyps are usually present, carcinoma causing a chronic bleed, haemorrhoids. (12 Dec 1998) |
| anterior surface of lower limb | The anterior surface of the inferior limb. Synonym: facies anterior membri inferioris. (05 Mar 2000) |
| arterial arch of lower eyelid | Formed by the medial palpebral artery which communicates with a branch of the lacrimal artery along the tarsal margin. Synonym: arcus palpebralis inferior. (05 Mar 2000) |
| bones of lower limb | These include the inferior limb girdle (hip bone) and the skeleton of the free inferior limb (femur, tibia, fibula, patella, tarsus, metatarsus, and bones of the toes). Synonym: ossa membri inferioris, bones of inferior limb. (05 Mar 2000) |
| regions of lower limb | The topographic divisions of the lower limb: gluteal, thigh (or femoral), knee, leg (or crural), ankle, and foot. Synonym: regiones membri inferioris, regions of inferior limb. (05 Mar 2000) |
| mean lower low water | <marine biology> The average height of the lower low waters over a 19-year period. For shorter periods of observations, corrections are applied to eliminate known variations and reduce the result to the equivalent of a mean 19-year value. (09 Oct 1997) |
| 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) |
| posterior surface of lower limb | The posterior surface of the inferior limb. Synonym: facies posterior membri inferioris. (05 Mar 2000) |