| vertical classification | <zoology> Classification which stresses common descent and tends to unite ancestral and descendant groups of a phyletic line in a single higher taxon, separating them from contemporaneous taxa having reached a similar grade of evolutionary change. Compare: Horizontal classification. (09 Jan 1998) |
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| vertical dimension | The length of the face determined by the distance of separation of jaws. Occlusal vertical dimension (ovd or vdo) or contact vertical dimension is the lower face height with the teeth in centric occlusion. Rest vertical dimension (vdr) is the lower face height measured from a chin point to a point just below the nose, with the mandible in rest position. (12 Dec 1998) |
| vertical displacement event | Disruption which occurs because plasma is not adequately stabilised against vertical motions. (09 Oct 1997) |
| vertical elastic | Elastic material used in a direction perpendicular to the occlusal plane, connecting one arch wire to the other, and usually used to improve intercuspation. (05 Mar 2000) |
| vertical growth phase | Spread of melanoma cells from the epidermis into the dermis and later the subcutis, from which site metastasis may take place. (05 Mar 2000) |
| vertical heart | Loosely descriptive of the heart's electrical axis when this is directed at approximately +90 |
| vertical hymen | A hymen in which the opening is perpendicular. (05 Mar 2000) |
| vertical illumination | <microscopy> Bright field illumination by light from the objective which is reflected or scattered from the (usually opaque) object. Illumination is by means of a vertical illuminator placed above the objective. Light is brought into a side tube and directed toward the back aperture of the objective by a tiny mirror or prism, or else by a full-aperture transparent-reflector (thin glass plate) 45[macron] to the axis of the bodytube. (05 Aug 1998) |
| vertical index | The relation of the height to the length of the skull: (height × 100)/length. Synonym: height-length index, length-height index, transversovertical index. (05 Mar 2000) |
| vertical muscle of tongue | An intrinsic muscle of the tongue, consisting of fibres that pass from the aponeurosis of the dorsum to the aponeurosis of the inferior surface; action, decreases the superior to inferior dimension of (flattens) the tongue; nerve supply, hypoglossal for motor, lingual for sensory. Synonym: musculus verticalis linguae. (05 Mar 2000) |
| vertical nystagmus | An up-and-down oscillation of the eyes. (05 Mar 2000) |
| vertical opening | The length of the face determined by the distance of separation of jaws. Occlusal vertical dimension (ovd or vdo) or contact vertical dimension is the lower face height with the teeth in centric occlusion. Rest vertical dimension (vdr) is the lower face height measured from a chin point to a point just below the nose, with the mandible in rest position. (12 Dec 1998) |
| vertical osteotomy | An oral surgical procedure similar to sliding oblique osteotomy. (05 Mar 2000) |
| vertical overlap | The extension of the upper teeth over the lower teeth in a vertical direction when the opposing posterior teeth are in contact in centric occlusion, the distance that teeth lap over their antagonists vertically, especially for the distance that the upper incisal edges drop below the lower ones, but may also describe the vertical relations of opposing cusps, the relationship of the maxillary incisors to the mandibular incisors when the incisal edges pass each other in centric occlusion. Synonym: overbite. (05 Mar 2000) |
| vertical parallax | The relative vertical displacement of the image when each eye is closed in turn; seen in vertical diplopia, or heterophoria. (05 Mar 2000) |