| preceding | 1. Going before; opposed to following. 2. <astronomy> In the direction toward which stars appear to move. See Following. Source: Websters Dictionary (01 Mar 1998) |
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| precentral | Referring to the cerebral convolution immediately anterior to the central sulcus: precentral gyrus. (05 Mar 2000) |
| precentral area | The cortex of the precentral gyrus. (05 Mar 2000) |
| precentral artery | <anatomy, artery> A branch of the terminal part of the middle cerebral artery distributed to the cortex on either side of the precentral sulcus. Synonym: arteria sulci precentralis, artery of precentral sulcus, pre-Rolandic artery, precentral artery. (05 Mar 2000) |
| precentral cerebellar vein | <anatomy, vein> An unpaired vein originating in the precentral cerebellar fissure passing anterior and superior to the culmen on its way to terminate in the great cerebral vein. Synonym: vena precentralis cerebelli. (05 Mar 2000) |
| precentral gyrus | Bounded posteriorly by the central sulcus and anteriorly by the precentral sulcus. Synonym: gyrus precentralis, anterior central convolution, anterior central gyrus, ascending frontal convolution, ascending frontal gyrus. (05 Mar 2000) |
| precentral sulcal artery | <anatomy, artery> A branch of the terminal part of the middle cerebral artery distributed to the cortex on either side of the precentral sulcus. Synonym: arteria sulci precentralis, artery of precentral sulcus, pre-Rolandic artery, precentral artery. (05 Mar 2000) |
| precentral sulcus | An interrupted fissure anterior to and in general parallel with the central sulcus, marking the anterior border of the precentral gyrus. Synonym: sulcus precentralis, sulcus verticalis. (05 Mar 2000) |
| preceptial | Preceptive. "[Passion] would give preceptial medicine to rage." (Shak) Source: Websters Dictionary (01 Mar 1998) |
| preceptorship | An educational program designed to give the professionally trained student experience outside the academic environment working in the specialty area of his choice with a physician, dentist or other advisory supervisors. (12 Dec 1998) |
| preceptress | A woman who is the principal of a school; a female teacher. Source: Websters Dictionary (01 Mar 1998) |
| precervical sinus | In young mammalian embryos a depression in the nuchal region caudal to the hyoid arch, with the third and fourth branchial arches and ectodermal grooves in its floor; normally it is obliterated after the second month, but occasionally cervical fistulae persist as vestiges of it. Synonym: precervical sinus. (05 Mar 2000) |
| precession | The act of going before, or forward. Lunisolar precession. <astronomy> The slow backward motion of the equinoctial points along the ecliptic, at the rate of 50.2<sec/ annually, caused by the action of the sun, moon, and planets, upon the protuberant matter about the earth's equator, in connection with its diurnal rotation; so called because either equinox, owing to its westerly motion, comes to the meridian sooner each day than the point it would have occupied without the motion of precession, and thus precedes that point continually with reference to the time of transit and motion. Origin: L. Praecedere, praecessum, to go before: cf. F. Precession. See Precede. Source: Websters Dictionary (01 Mar 1998) |
| prechiasmatic sulcus | The groove on the upper surface of the sphenoid bone running transversely between the optic canals bounded anteriorly by the sphenoidal limbus and posteriorly by the tuberculum sellae; forms in relationship to the optic chiasm. Synonym: sulcus prechiasmatis, chiasmatic sulcus, optic groove, prechiasmatic sulcus. (05 Mar 2000) |
| prechordal | <anatomy> Situated in front of the notochord; applied especially to parts of the cartilaginous rudiments in the base of the skull. Origin: Pref. Pro + chordal. Source: Websters Dictionary (01 Mar 1998) |