| fourth parallel pelvic plane | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
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| Frankfort horizontal plane | A standard craniometric reference plane passing through the right and left porion and the left orbitale; drawn on the profile radiograph or photograph from the superior margin of the acoustic meatus to the orbitale. Synonym: auriculo-infraorbital plane, eye-ear plane, Frankfort horizontal plane, Frankfort plane, infraorbitomeatal plane. (05 Mar 2000) |
| Frankfort plane | A standard craniometric reference plane passing through the right and left porion and the left orbitale; drawn on the profile radiograph or photograph from the superior margin of the acoustic meatus to the orbitale. Synonym: auriculo-infraorbital plane, eye-ear plane, Frankfort horizontal plane, Frankfort plane, infraorbitomeatal plane. (05 Mar 2000) |
| frontal plane | A vertical plane at right angles to a sagittal plane, dividing the body into anterior and posterior portions. Synonym: frontal plane. (05 Mar 2000) |
| acromial angle | The prominent angle at the junction of the posterior and lateral borders of the acromion. Synonym: angulus acromialis. (05 Mar 2000) |
| acute angle | Any angle less than 90 |
| acute angle closure glaucoma | <ophthalmology> An increase in pressure within the anterior chamber of the eye. There are two forms of glaucoma: acute angle closure and open angle glaucoma. (27 Sep 1997) |
| adjacent angle | An angle with a line in common with another angle. (05 Mar 2000) |
| alpha angle | The angle between the visual and optic axes as they cross at the nodal point of the eye, the angle between the visual line and the major axis of the corneal ellipse. (05 Mar 2000) |
| alveolar angle | The angle between the horizontal plane and a line connecting the base of the nasal spine and the middle point of the projection of the alveolus of the maxilla. (05 Mar 2000) |
| angle | 1. To fish with an angle (fishhook), or with hook and line. 2. <geometry> The figure made by two lines which meet. The difference of direction of two lines. In the lines meet, the point of meeting is the vertex of the angle. 3. A projecting or sharp corner; an angular fragment. "Though but an angle reached him of the stone." (Dryden) Curvilineal angle, one formed by two curved lines. External angles, angles formed by the sides of any right-lined figure, when the sides are produced or lengthened. Internal angles, those which are within any right-lined figure. Mixtilineal angle, one formed by a right line with a curved line. Oblique angle, one acute or obtuse, in opposition to a right angle. Obtuse angle, one greater than a right angle, or more than 90 deg . Rectilineal or Right-lined angle, one formed by two right lines. Right angle, one formed by a right line falling on another perpendicularly, or an angle of 90 deg (measured by a quarter circle). Solid angle, the figure formed by the meeting of three or more plane angles at one point. Spherical angle, one made by the meeting of two arcs of great circles, which mutually cut one another on the surface of a globe or sphere. Visual angle, the angle formed by two rays of light, or two straight lines drawn from the extreme points of an object to the center of the eye. 4. <astronomy> A name given to four of the twelve astrological houses. Origin: F. Angle, L. Angulus angle, corner; akin to uncus hook, Gr. Bent, crooked, angular, a bend or hollow, AS. Angel hook, fish-hook, G. Angel, and F. Anchor. (16 Mar 1998) |
| angle closure glaucoma | <ophthalmology> Primary glaucoma in which contact of the iris with the peripheral cornea excludes aqueous humor from the trabecular drainage meshwork causing a sudden blockage of the normal fluid circulation within the eyeball resulting in increased intraocular pressure. Increased pressure within the eyeball can cause damage to the optic nerve and blindness. Symptoms include severe eye or facial pain, nausea, vomiting, decreased vision, blurred vision and seeing halos around objects. The eye appears red with a steamy cornea and a fixed (nonreactive) dilated pupil. Treatment is emergent with medications to lower the pressure within the eye. Synonym: acute glaucoma, closed-angle glaucoma, narrow-angle glaucoma. (14 Aug 2000) |
| Angle, Edward | <person> U.S. Orthodontist, 1855-1930. See: Angle's classification of malocclusion. (05 Mar 2000) |
| angle of anomaly | <ophthalmology> An obsolete term for the degree of deviation from parallelism of the visual axes of the eyes. (05 Mar 2000) |
| angle of antetorsion | <orthopaedics> The angle formed by a line drawn through the centre of the long axis of the neck of the femur meeting a line drawn in the transverse axis of the condyles, when the bone is viewed from above, looking straight down through the head of the femur. It is used to illustrate the normal degree of anteversion about 12 |