| ASD | Atrial Septal Defect Types of ASD 1. Ostium Primum ASD ... |
|---|---|
| CS | calf serum; campomelic syndrome; carcinoid syndrome; cardiogenic shock; caries-susceptible; carotid ... |
| CSI | calculus surface index; cancer serum index; cavernous sinus infiltration; cervical spine injury; che... |
| SA | salicylic acid; saline [solution]; salt added; sarcoidosis; sarcoma; scalenus anticus; secondary ame... |
| SSS | scalded skin syndrome; secondary Sjogren syndrome; sick sinus syndrome; specific soluble substance; ... |
| sphenoidal ridges | Sharp posterior margins of the lesser wings of the sphenoid bone which end medially in the anterior clinoid process; the sphenoidal ridges demarcate the anterior cranial fossa from the lateral part of the middle cranial fossa. (05 Mar 2000) |
|---|---|
| sphenoidal spine | A posterior and downward projection from the greater wing of the sphenoid bone on either side, located posterolateral to the foramen spinosum, so-named for its proximity to the sphenoidal spine; gives attachment to the sphenomandibular ligament. Synonym: processus spinosus, spina ossis sphenoidalis, alar spine, angular spine, spina angularis, spinous process. (05 Mar 2000) |
| sphenoidal turbinated bones | Paired ossicles of pyramidal shape, the spines of which are in contact with the medial pterygoid lamina, the bases forming the roof of the nasal cavity. Synonym: conchae sphenoidales, Bertin's bones, Bertin's ossicles, sphenoidal turbinated bones. (05 Mar 2000) |
| emissary sphenoidal foramen | <anatomy> A minute inconstant foramen in the greater wing of the sphenoid bone, anterior and medial to the foramen ovale, transmitting a small emissary vein from the cavernous sinus. Synonym: emissary sphenoidal foramen, venous foramen, Vesalius' foramen. (05 Mar 2000) |
| angle of aperture | <ophthalmology, optics> The angle formed by lines drawn from the ends of the diameter of a lens to its point of focus. See: angular aperture. (05 Mar 2000) |
| angular aperture | The angle, in air, of light that passes from the object to the ends of the diameter of the front lens of the microscope objective. (05 Mar 2000) |
| anterior nasal aperture | The anterior nasal opening in the skull. Synonym: apertura piriformis, piriform opening. (05 Mar 2000) |
| aperture | <physics> The opening in an optical system which restricts the size of the bundle of rays incident on a given surface. (Usually circular and specified by diameter.) (09 Oct 1997) |
| aperture, angular | <microscopy> The angle between the most divergent rays that can pass through a lens to form the image of an object. The angle subtended between the axis of a lens and the largest accepted angle of the image-forming rays. With microscope objectives the trigonometric sine of this angle is used to define numerical aperture but as measured from the axial object point. (05 Aug 1998) |
| aperture correction | <microscopy> An electronic process used in some high-resolution video cameras and monitors that compensates for the loss in sharpness of detail due to the finite dimensions (aperture) of the scanning beam. (05 Aug 1998) |
| aperture diaphragm | A metal device that limits the area of the beam emerging from an X-ray tube. (05 Mar 2000) |
| aperture, effective | <microscopy> The diameter of the entrance pupil: it is the apparent diameter of the limiting aperture measured from the front. (05 Aug 1998) |
| aperture for electron microscopy | <technique> Anode aperture: The opening in the accelerating voltage anode shield of the electron gun through which the electrons must pass to irradiate the specimen. Condenser aperture: An opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the electron beam. The angular aperture can also be controlled by the condenser lens current. Physical objective aperture: A metallic diaphragm, with a small central hole, used to limit the cone of electrons accepted by the objective lens. This improves image-contrast since highly scattered electrons are prevented from arriving at the Gaussian image plane and therefore cannot contribute to background fog. Aplanatic. Free from spherical aberration and coma. (05 Aug 1998) |
| aperture function | <microscopy> In a diffraction-limited optical system, the function that determines the relationship between the image and each point in the object. Modifying the aperture function changes the image according to the modified Fourier-filtering (or optical filtration) property of the aperture. (05 Aug 1998) |
| aperture of mastoid antrum | The orifice leading from the epitympanic recess to the mastoid antrum. Synonym: aditus ad antrum. (05 Mar 2000) |