# vertex

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## vertex

[ver´teks]the summit or top, especially the top of the head (ver´tex cra´nii).

## ver·tex

, pl.## ver·ti·ces

(ver'teks, vĕr'ti-sēz), [TA]**1.**The topmost point of the vault of the skull, a landmark in craniometry.

**2.**obstetrics the portion of the fetal head bounded by the planes of the trachelobregmatic and biparietal diameters, with the posterior fontanel at the apex.

[L. whirl, whorl]

## vertex

/ver·tex/ (ver´teks) pl.*ver´tices*[L.] the summit or top, especially the top of the head

*(v. cra´nii)*.ver´tical

## vertex

(vûr′tĕks′)*n.*

*pl.*

**ver·tices**(-tĭ-sēz′) also

**ver·texes**

**1.**The highest point; the apex or summit: the vertex of a mountain.

**2.**

*Anatomy*

**a.**The highest point of the skull.

**b.**The top of the head.

**3.**In astrology, the highest point reached in the apparent motion of a celestial body.

**4.**

*Mathematics*

**a.**The point at which the sides of an angle intersect.

**b.**The point on a triangle or pyramid opposite to and farthest away from its base.

**c.**A point on a polyhedron common to three or more sides.

**d.**A point of maximal curvature on a parabola or hyperbola.

## vertex

[vur′teks]

Etymology: L, summit

**1**the top of the head; crown.

**2**the apex or highest point of any structure.

## ver·tex

, pl.**vertices**(vĕr'teks, -ti-sēz) [TA]

**1.**The topmost point of the vault of the cranium, a landmark in craniometry.

**2.**obstetrics The portion of the fetal head bounded by the planes of the trachelobregmatic and biparietal diameters, with the posterior fontanel at the apex.

[L. whirl, whorl]

## vertex

**1.**The top of the head.

**2.**Any apex or highest point on a body structure.

## vertex

- an area on the head of an insect between the compound eyes.
- the top of the head.

## vertex

The point where the optical axis intersects a reflecting or refracting surface. In a spectacle lens the back vertex is the point of intersection of the optical axis with the surface nearest to the eye, the other being the front vertex.

where

*Plural*: vertices.**vertex depth**Distance between the posterior pole of a spectacle lens and the plane containing the posterior edge of the lens. The vertex depth*s*is given by the following formula*s*=

*r*− Î(

*r*

^{2}−

*y*

^{2})

*r*is the radius of curvature of the surface of the spectacle lens and*y*is the semi-diameter at the edge of the surface (Fig. V3).*Syn.*sag.*See*apical clearance;**lens measure**.**vertex distance**Distance along the line of sight between the apex of the cornea and the posterior surface of a spectacle lens. This distance normally varies between 11 mm and 15 mm.*See*apical clearance; spectacle plane.**vertex focal length**The linear distance separating the principal focal point (focus) of an optical system or lens from the front or back vertices. They are called the**front vertex focal length**(*f*_{v}) and the**back vertex focal length**(*f*′_{v}), respectively. In the case of a biconcave or biconvex lens the front and back vertex focal lengths are equal. In the case of a positive meniscus lens, the back vertex focal length is shorter than the front vertex focal length and vice versa in the case of a negative meniscus lens.*See*back vertex power;**front vertex power**.**vertex power***See*back vertex power;**front vertex power**.Table V1 Vertex depths of various spherical surfaces. They also represent the centre thickness of a planoconvex lens with a front surface of radius of curvature r and diameter 2y, with an edge thickness of zero. Index of refraction of the lens 1.49 | ||||||||||

lens diameter 2y (mm) | ||||||||||

surface power (D) | radius r(mm) | 40 | 50 | 60 | 70 | |||||

1 | 490 | 0.41 | 0.64 | 0.92 | 1.25 | |||||

2 | 245 | 0.82 | 1.28 | 1.84 | 2.51 | |||||

3 | 163.3 | 1.23 | 1.92 | 2.78 | 3.79 | |||||

4 | 122.5 | 1.64 | 2.58 | 3.73 | 5.11 | |||||

5 | 98 | 2.06 | 3.24 | 4.70 | 6.46 | |||||

6 | 81.7 | 2.49 | 3.92 | 5.71 | 7.88 | |||||

7 | 70 | 2.92 | 4.62 | 6.75 | 9.38 | |||||

8 | 61.3 | 3.38 | 5.33 | 7.85 | 10.99 | |||||

9 | 54.4 | 3.81 | 6.08 | 9.01 | 12.74 | |||||

10 | 49 | 4.27 | 6.86 | 10.26 | 14.71 | |||||

12 | 40.8 | 5.23 | 8.55 | 13.13 | 19.80 | |||||

14 | 35 | 6.28 | 10.51 | 16.97 | 35.00 | |||||

16 | 30.6 | 7.43 | 12.94 | 24.47 | ||||||

18 | 27.2 | 8.75 | 16.45 | |||||||

20 | 24.5 | 10.35 |

## vertex

the summit or top, especially the top of the head.

**vertex corneae**

central part of the cornea.

## Patient discussion about vertex

**Q. What could make the top of your head hurt to the touch. I don't have a headache. It just hurts when I touch** It only hurts on the left side.

**A.**if it's a deep pain- it might be caused by a trauma to the bode. have you been hurt by something..? if you don't remember - it might be a memory loss from the hit to the head :)

if it's a sort of superficial pain- it might be caused of a wound there. ask someone to have a look and see if there's anything over there. it could even be a tic sitting there...