aperture

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aperture

 [ap´er-chur]
inferior aperture of minor pelvis (inferior aperture of pelvis) pelvic outlet.
numerical aperture an expression of the measure of efficiency of a microscope objective.
superior aperture of minor pelvis (superior aperture of pelvis) pelvic inlet.

ap·er·ture

(ap'er-chūr),
1. Opening. An inlet or entrance to a cavity or channel. In anatomy, a gap or hole.
See also: fossa, ostium, orifice, pore. Synonym(s): apertura [TA]
2. The diameter of the objective of a microscope.
Synonym(s): aditus [TA]
[L. apertura, an opening]

aperture

/ap·er·ture/ (ap´er-cher) opening.
piriform aperture  the anterior end of the bony nasal opening, connecting the external nose with the skull.

aperture

[ap′ərchər]
Etymology: L, apertura, an opening
an opening or hole in an object or anatomical structure.

ap·er·ture

(ap'ĕr-chŭr) [TA]
1. An inlet or entrance to a cavity or channel; in anatomy, an open gap or hole.
2. The diameter of the objective of a microscope.
Synonym(s): aditus [TA] , apertura [TA] .
[L. apertura, an opening]

aperture 

An opening, or the area of a lens, through which light can pass. See pupil.
angular aperture Half of the maximum plane subtended by a lens at the axial point of an object or image. (Sometimes the full plane angle is taken as the angular aperture but this is not convenient in optical calculations.) See sine condition.
aperture of a lenticular lens That portion of a lenticular lens which has the prescribed power (British Standard).
numerical aperture An expression designating the light-gathering power of microscope objectives. It is equal to the product of the index of refraction n of the object space and the sine of the angle u subtended by a radius of the entrance pupil at the axial point on the object, i.e. n sin u.
palpebral aperture The gap between the margins of the eyelids when the eye is open. An abnormal increase in the aperture occurs in some conditions, including Graves' disease, buphthalmos, Parinaud's syndrome and retrobulbar tumour. An abnormal decrease in the aperture occurs in some conditions, including ptosis, microphthalmos and ophthalmoplegia (Figs. A15 and A16). Syn. interpalpebral fissure (this term is more accurate although used infrequently); palpebral fissure. See exophthalmos.
aperture plane See aperture plane.
aperture ratio See relative aperture.
relative aperture The reciprocal of the f number. It is therefore equal to the ratio of the diameter of the entrance pupil to the primary focal length of an optical system. Syn. aperture ratio. Note: the definition of this term is not universally accepted; some authors define it as the reverse of the above. See antimongoloid slant; f number.
Fig. A15 Palpebral aperture PA and corneal apex CAenlarge picture
Fig. A15 Palpebral aperture PA and corneal apex CA
Fig. A16 Average dimensions of the normal palpebral aperture of a Caucasian eyeenlarge picture
Fig. A16 Average dimensions of the normal palpebral aperture of a Caucasian eye

ap·er·ture

(ap'ĕr-chŭr) [TA]
1. [TA] Opening. An inlet or entrance to a cavity or channel. In anatomy, a gap or hole.
Synonym(s): apertura.
2. The diameter of the objective of a microscope.
See also: fossa, ostium, orifice
Synonym(s): aditus [TA] .
[L. apertura, an opening]

aperture,

n an opening such as in bone.

aperture

an opening.

nasal aperture
the opening on the skull bounded by the nasal and incisive bones.
nasomaxillary aperture
the connecting aperture between the middle nasal meatus and the maxillary sinuses.
numerical aperture
measure of efficiency of a microscope objective proportional to the square root of the amount of light entering the instrument.
References in periodicals archive ?
The cause for radical ultimate chamber expansion along with an increase in apertural size or number (or both) remains difficult to explain.
62), often with only embryonic whorls projecting in apertural view; final part of last adult whorl descending prior to aperture, but not steeply so; whorls more or less evenly rounded, suture indented; umbilicus very wide, its margin evenly rounded, underside of embryonic whorls clearly visible.
SEM images are displayed in vertical columns, one column per genus, and characterise four views: polar, apertural, equatorial, and fractured sections, sometimes taken from different species in a genus, often from different collections of the same species, in order to document as much variation and/or similarity within groups as possible.
Shell ornamentation, an increase in shell size or thickness, and complex apertural morphology may have evolved in response to changes in the type and strength of predation (Vermeij 1977).
Shell length and diameter measurements were made with the shell held in apertural view with the axis of coiling vertical.
It is a subadult specimen in which the apertural dentition is not fully developed (Fig.
Apertural sculpturing: (0) smooth to finely verrucate; (1) coarsely granulate; (2) pore, no sculpturing.
10 ridge-like denticles, with an additional row of smaller granules just inside lip edge; apertural dentition absent in immature specimens, in these the outer lip is strongly notched at ends of spiral cords; interior nacreous, weakly angled beneath external cords, but labral denticles not extending into aperture as in-running ridges.
Grains with an apertural system consisting of three compound