| HEIR | health effects of ionizing radiation; high-energy ionizing radiation |
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| RO | radiation oncology; radiation output; ratio of; relative odds; renal osteodystrophy; reverse osmosis... |
| RR | radiation reaction; radiation response; rate ratio; rational recovery [group]; recovery room; relati... |
| LASER | Light Amplication by Stimulated Emission of Radiation |
| rad | radiation absorbed dose |
| pyramidal lobe of thyroid gland | <anatomy> An inconstant narrow lobe of the thyroid gland that arises from the upper border of the isthmus and extends upward, sometimes as far as the hyoid bone; it marks the point of continuity with the thyroglossal duct. Synonym: lobus pyramidalis glandulae thyroideae, Lallouette's pyramid, Morgagni's appendix, pyramid of thyroid. (05 Mar 2000) |
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| pyramidal muscle | <anatomy, muscle> Origin, crest of pubis; insertion, lower portion of linea alba; action, makes linea alba tense; nerve supply, subcostal. Synonym: musculus pyramidalis, pyramidal muscle. (05 Mar 2000) |
| pyramidal muscle of auricle | <anatomy> An occasional prolongation of the fibres of the tragicus to the spina helicis. Synonym: musculus pyramidalis auriculae, Jung's muscle, pyramidal muscle of auricle. (05 Mar 2000) |
| pyramidal process | The portion of the palatine bone passing lateral and posterior from the angle formed by the vertical and horizontal plates. Synonym: processus pyramidalis. (05 Mar 2000) |
| pyramidal tract | A massive bundle of fibres originating from pyramidal cells of various sizes in the fifth layer of the precentral motor (area 4), the premotor area (area 6), and to a lesser extent from the postcentral gyrus. Cells of origin in area 4 include the gigantopyramidal cells of Betz. Fibres from these cortical regions descend through the internal capsule, the middle third of the crus cerebri, and the ventral part of the pons to emerge on the ventral surface of the medulla oblongata as the pyramis. Continuing caudally, most of the fibres cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord as the lateral pyramidal tract, which distributes its fibres throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. In the (extremity-related) spinal cord enlargements, fibres also pass directly to motoneuronal groups that innervate distal extremity muscles subserving particular hand-and-finger or foot-and-toe movements. The uncrossed fibres form a small bundle, the anterior pyramidal tract, which descends in the anterior funiculus of the spinal cord and terminates in synaptic contact with interneurons in the medial half of the anterior horn on both sides of the spinal cord. Interruption of the pyramidal tract at or below its cortical origin causes impairment of movement in the opposite body-half, especially severe in the arm and leg; characterised by muscular weakness, spasticity and hyperreflexia, and a loss of discrete finger and hand movements. Babinski's sign is associated with this condition of hemiplegia. Synonym: tractus corticospinalis, tractus pyramidalis, corticospinal tract. (05 Mar 2000) |
| pyramidal tractotomy | May be mesencephalic (pedunculotomy or crusotomy), medullary (medullary pyramidotomy), or spinal (spinal pyramidotomy). (05 Mar 2000) |
| direct pyramidal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| lateral pyramidal fasciculus | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| lateral pyramidal tract | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| abnormalities, radiation-induced | Congenital changes in the morphology of organs produced by exposure to ionizing or non-ionizing radiation. (12 Dec 1998) |
| accidents, radiation | Accidental dispersal of radioactive materials from a radiation source. Accidents at nuclear reactors can involve large groups of the population from dispersion of radioactivity into the environment and through fallout or a few individuals with high injurious doses. (12 Dec 1998) |
| acoustic radiation | The fibres that pass from the medial geniculate body to the transverse temporal gyri of the cerebral cortex by way of the sublentiform part of the internal capsule. Synonym: radiatio acustica. (05 Mar 2000) |
| acute radiation syndrome | <syndrome> A syndrome caused by exposure of the body to large amounts of radiation, (e.g., from certain forms of therapy, accidents, and nuclear explosions; it is divided into three major forms which are, in ascending order of severity, the haematogic, gastrointestinal, and central nervous system-cardiovascular forms; its clinical manifestations are divided into prodromal, latent, overt, and recovery stages. (05 Mar 2000) |
| adaptive radiation | <chemistry> The evolution of new speciesor sub-species to fill unoccupied ecological niches. (06 May 1997) |
| alpha radiation | <physics, radiobiology> The most easily absorbable type of radiation, it consists of a stream of alpha particles, doubly ionised helium nuclei which are electrically charged and produce intense ionisation in matter. Alpha radiation can be deflected in electromagnetic fields. (09 Oct 1997) |