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 classic literature ?
It showed no aperture in the mighty walls other than the tiny door at which I sank exhausted, nor was there any sign of life about it.
through a narrow aperture in its front; and facing you, on entering, lay two long, perfectly straight, and well-polished trunks of the cocoanut tree, extending the full length of the dwelling; one of them placed closely against the rear, and the other lying parallel with it some two yards distant, the interval between them being spread with a multitude of gaily-worked mats, nearly all of a different pattern.
Not once did one leave the cliff by any other opening save that from which I had seen the first party come, nor did any re-enter the cliff through another aperture.
I therefore repeated the word after her; but when I saw the expression in her eyes as they were directed past me and saw her point toward the entrance to the cave, I turned quickly--to see a hideous face at the small aperture leading out into the night.
At more or less regular stages it was pierced by apertures closed by doors, none of which he could open until he had climbed fully fifty feet from the river level.
The size and shape of the apertures in the sternum are highly variable; so is the degree of divergence and relative size of the two arms of the furcula.
The fish, having remained in this distended state for a short time, generally expelled the air and water with considerable force from the branchial apertures and mouth.
Of its five apertures, only the skylight and the two doors were large enough for the passage of a man.
Rising at five o'clock next morning, I took a walk about the village: none of the houses were strolling about to-day, but it was early for them yet, perhaps: and then amused myself by lounging in a kind of farm-yard behind the tavern, of which the leading features were, a strange jumble of rough sheds for stables; a rude colonnade, built as a cool place of summer resort; a deep well; a great earthen mound for keeping vegetables in, in winter time; and a pigeon-house, whose little apertures looked, as they do in all pigeon-houses, very much too small for the admission of the plump and swelling-breasted birds who were strutting about it, though they tried to get in never so hard.
While some small parties kindled bonfires underneath the windows, others broke up the furniture and cast the fragments down to feed the flames below; where the apertures in the wall (windows no longer) were large enough, they threw out tables, chests of drawers, beds, mirrors, pictures, and flung them whole into the fire; while every fresh addition to the blazing masses was received with shouts, and howls, and yells, which added new and dismal terrors to the conflagration.
The apertures, where doors and windows stood an hour ago, disclosed a mass of raging fire; walls rocked and crumbled into the burning well; the molten lead and iron poured down, white hot, upon the ground.
In a large and lofty building, supported by pillars of iron, with great black apertures in the upper walls, open to the external air; echoing to the roof with the beating of hammers and roar of furnaces, mingled with the hissing of red-hot metal plunged in water, and a hundred strange unearthly noises never heard elsewhere; in this gloomy place, moving like demons among the flame and smoke, dimly and fitfully seen, flushed and tormented by the burning fires, and wielding great weapons, a faulty blow from any one of which must have crushed some workman's skull, a number of men laboured like giants.