| D3-12 | third to twelfth dorsal vertebrae |
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| DSM-III-R | Diagnostic and Statistical Manual of Mental Disorders [of APA], third edition, revised |
| L1, | L2, L3, L4, L5 first, second, third, fourth, and fifth lumbar vertebrae |
| LI, LII, | LIII first, second, third stage of syphilis |
| L/3 | lower third |
| 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) |
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| 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) |
| Abbe's law of limiting resolution | <physics> For a periodic structure of units separated by distance d and obliquely illuminated by the unrefracted ray and one of the two diffracted rays (extremely oblique illumination). Abbe applied the law of diffraction: d = 0.5 lambda /NA, where: lambda = wavelength of the monochromic light or shortest of mixed wavelengths NA = the limiting numerical aperture (NA) of objective or condenser. (05 Aug 1998) |
| all or none law | Consistently total response to any effective stimulus. Synonym: all or none law. (05 Mar 2000) |
| American Law Institute formulation | Used in certain jurisdictions to determine criminal responsibility in legal proceedings. See: criminal insanity. (05 Mar 2000) |
| American Law Institute rule | A test of criminal responsibility (1962): "a person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of law." (05 Mar 2000) |
| Ampere's law | <physics> General equation in electromagnetism relating the magnetic field and the currents generating it. The various forms of the equation can be found in an introductory electromagnetism text. (09 Oct 1997) |
| Angstrom's law | A substance absorbs light of the same wavelength as it emits when luminous. (05 Mar 2000) |
| Arndt's law | An obsolete law stating that weak stimuli excite physiologic activity, moderately strong ones favour it, strong ones retard it, and very strong ones arrest it. (05 Mar 2000) |
| Arrhenius law | The theory of electrolytic dissociation (1887) that became the basis of our modern understanding of electrolytes: in an electrically conductive solution (e.g., acid, base, or salt), free ions are present before electrolysis, and the proportion of molecules dissociated into ions can be calculated from measurements of electrical conductivity as well as of osmotic pressure. Synonym: Arrhenius law. (05 Mar 2000) |
| Avogadro's law | Equal volumes of gases contain equal numbers of molecules, the conditions of pressure and temperature being the same. Synonym: Ampere's postulate, Avogadro's hypothesis, Avogadro's postulate. (05 Mar 2000) |