| ROA | right occipitoanterior [fetal position] |
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| ROI | reactive oxygen intermediate; region of interest; right occipitolateral [fetal position] |
| ROP | removal of pins or plates; removal of plaster [of Paris]; retinopathy of prematurity; right occipito... |
| ROT | real oxygen transport; remedial occupational therapy; right occipito-transverse [fetal position] |
| RSA | rabbit serum albumin; regular spiking activity; relative specific activity; relative standard accura... |
| anterior part of pons | The large ventral part of the pons occupied by the nuclei pontis, traversed longitudinally by corticopontine, corticobulbar, and corticospinal fibres, and transversely by pontocerebellar fibres. Pontocerebellar fibres converging laterally form the middle cerebellar peduncle or brachium pontis. Synonym: pars ventralis pontis, anterior part of pons, basilar part of pons, pars basilaris pontis. (05 Mar 2000) |
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| anterior pelvic exenteration | Removal of the urinary bladder, lower parts of the ureter, vagina, uterus, adnexa, and adjacent lymph nodes; a urinary diversion is necessary. (05 Mar 2000) |
| anterior perforated substance | A region at the base of the brain through which numerous small branches of the anterior and middle cerebral arteries (lenticulostriate arteries) enter the depth of the cerebral hemisphere; it is bordered medially by the optic chasm and anterior half of the optic tract, rostrally and laterally by the lateral olfactory stria; its anteromedial part corresponds to the olfactory tubercle. Synonym: substantia perforata anterior, locus perforatus anticus, olfactory area. (05 Mar 2000) |
| anterior peroneal artery | See: perforating branches. (05 Mar 2000) |
| anterior pillar of fauces | One of a pair of ridges or folds of mucous membrane passing from the soft palate to the side of the tongue; it encloses the palatoglossus muscle and forms anterior margin of the tonsillar fossa. Also demarcates oral cavity from isthmus of fauces. Synonym: arcus palatoglossus, anterior palatine arch, anterior pillar of fauces, arcus glossopalatinus, glossopalatine arch, glossopalatine fold. (05 Mar 2000) |
| anterior pillar of fornix | That part of the fornix that curves down in front of the thalamus and the interventricular foramen of Monro, then continues through the hypothalamus to the mamillary body; consisting primarily of fibres originating in the hippocampus and subiculum, the column of fornix is the direct continuation of the body of the fornix. Synonym: columna fornicis, anterior pillar of fornix. (05 Mar 2000) |
| anterior piriform gyrus | A gyrus covering deeply placed amygdaloid nucleus; concerned with olfactory function. Synonym: anterior piriform gyrus. (05 Mar 2000) |
| anterior pituitary gonadotropin | Any gonadotropin of hypophysial origin; formerly used to designate a single hormone, because it was thought that the anterior hypophysis secreted only one gonadotropin. Synonym: pituitary gonadotropic hormone. (05 Mar 2000) |
| anterior pituitary-like hormone | A glycoprotein with a carbohydrate fraction composed of d-galactose and hexosamine, extracted from the urine of pregnant women and produced by the placental trophoblastic cells; its most important role appears to be stimulation, during the first trimester, of ovarian secretion of the oestrogen and progesterone required for the integrity of conceptus; it appears to play no significant role in the last two trimesters of pregnancy, as the oestrogen and progesterone are then formed by the placenta. Synonym: anterior pituitary-like hormone, choriogonadotropin, chorionic gonadotropic hormone, chorionic gonadotrophic hormone, placenta gonadotropin, placentagonadotropin. (05 Mar 2000) |
| anterior pole of eyeball | The centre of the corneal curvature of the eye. Synonym: polus anterior bulbi oculi. (05 Mar 2000) |
| anterior pole of lens | The central point on the anterior surface of the lens of the eye. Synonym: polus anterior lentis. (05 Mar 2000) |
| anterior pontomesencephalic vein | A vein in the midline of the interpeduncular fossa on the superior and anterior aspects of the pons; it communicates with the basal vein superiorly and the petrosal vein inferiorly. Synonym: anterior pontomesencephalic vein. (05 Mar 2000) |
| anterior primary division | <anatomy, nerve> The larger, anterolaterally-directed major terminal branch (with the dorsal primary ramus) of all 31 pairs of mixed spinal nerves, formed at the intervertebral foramen. Most ventral primary rami, especially those involved in the innervation of the limbs, participate in the formation of the major nerve plexuses (cervical, brachial, and lumbosacral) and lose their identities. Most in the thoracic region, however, remain separate from adjacent rami to become the intercostal and subcostal nerves. Ventral primary rami provide innervation to the anterolateral body wall and trunk. Nomina Anatomica lists ventral primary rami as "rami ventrales" for each group of spinal nerves: 1) cervical (nervorum cervicalium ), 2) thoracic (nervorum thoracicorum ), 3) lumbar (nervorum lumbalium ), 4) sacral (nervorum sacralium )m, and 5) coccygeal (nervi coccygei ). Synonym: ramus ventralis nervi spinalis, anterior primary division. (05 Mar 2000) |
| anterior process of malleus | A slender spur running anteriorward from the neck of the malleus toward the petrotympanic fissure. Synonym: processus anterior mallei, Folli's process, follian process, long process of malleus, processus gracilis, processus ravii, Rau's process, Ravius' process, slender process of malleus. (05 Mar 2000) |
| anterior pyramid | An elongated, white prominence on the ventral surface of the medulla oblongata on either side along the anterior median fissure, corresponding to the pyramidal tract. Synonym: pyramis medullae oblongatae, anterior column of medulla oblongata, anterior pyramid. (05 Mar 2000) |