| banana orbit | <radiobiology> In a toroidal magnetic geometry, the fast spiraling of a charged particle around a magnetic field line is accompanied by a slow movement (drift) of the centre of the sprial. Particles with relatively low parallel energy are mirrored on the inside of the torus because the toroidal magnetic field has a 1/R dependence and is highest on the inside. The combination of mirroring and drift produces a special class of particle orbits. Projected onto a poloidal plane, the drift orbit has the shape of a banana. These orbits are responsible for neo-classical diffusion and bootstrap current. (09 Oct 1997) |
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| margin of orbit | The mostly sharp edge of the orbital opening which is the peripheral border of the base of the pyramid-shaped orbit. The superior half of the orbital rim is the supraorbital margin; the inferior half is the infraorbital margin. The frontal, maxillary, and zygomatic bones contribute to the orbital rim, which is generally strong to protect the orbital contents. Weak, potential fracture sites of the rim coincide with the sutures between the participating bones. Synonym: margin of orbit. (05 Mar 2000) |
| medial wall of orbit | The thin, rectangular wall of the orbit formed by the orbital plate of the ethmoid, lacrimal, frontal and a small part of the sphenoid bones; the fossa for the lacrimal sac lies at its anterior limit. Synonym: paries medialis orbitae. (05 Mar 2000) |
| roof of orbit | Formed by the orbital plate of the frontal bone and the lesser wing of the sphenoid bone, the optic canal opens at its posterior limit; an indentation, the fossa for the lacrimal gland, is located in the anterolateral part of the roof. Synonym: paries superior orbitae, superior wall of orbit. (05 Mar 2000) |
| superior wall of orbit | Formed by the orbital plate of the frontal bone and the lesser wing of the sphenoid bone, the optic canal opens at its posterior limit; an indentation, the fossa for the lacrimal gland, is located in the anterolateral part of the roof. Synonym: paries superior orbitae, superior wall of orbit. (05 Mar 2000) |
| inferior wall of orbit | The floor of the orbit; the shortest of the four walls of the orbit, sloping upward from the orbital margin; it is comprised of the maxilla and orbital process of the palatine bone. Synonym: paries inferior orbitae, inferior wall of orbit. (05 Mar 2000) |
| orbit | 1. <astronomy> The path described by a heavenly body in its periodical revolution around another body; as, the orbit of Jupiter, of the earth, of the moon. 2. An orb or ball. "Roll the lucid orbit of an eye." (Young) 3. <anatomy> The cavity or socket of the skull in which the eye and its appendages are situated. 4. <zoology> The skin which surrounds the eye of a bird. Origin: L. Orbita a track or rut made by a wheel, course, circuit, fr. Orbis a circle: cf. F. Orbite. See Orb. Source: Websters Dictionary (01 Mar 1998) |
| orbit evisceration | The surgical removal of the contents of the orbit. This includes the eyeball, blood vessels, muscles, fat, nerve supply, and periosteum. It should be differentiated from eye evisceration which removes the inner contents of the eye, leaving the sclera intact. (12 Dec 1998) |
| floor of orbit | The floor of the orbit; the shortest of the four walls of the orbit, sloping upward from the orbital margin; it is comprised of the maxilla and orbital process of the palatine bone. Synonym: paries inferior orbitae, inferior wall of orbit. (05 Mar 2000) |
| lateral wall of orbit | A triangular wall of the orbit formed by the zygomatic bone, the greater wing of the sphenoid bone, and a small part of the frontal bone; posteriorly it is bounded by the superior and inferior orbital fissures. Synonym: paries lateralis orbitae. (05 Mar 2000) |
| acetone body | <biochemistry> Any of the three compounds created by acetyl coenzyme A (acetoacetate, hydroxybutyrate, and acetone) which are water-soluble cellular fuels normally exported by the liver. They can build up in the blood and body tissues because of starvation, untreated diabetes mellitus, or other disorders that interfere with carbohydrate metabolism. The body rids itself of ketones mainly through urine, but it rids itself of acetone through the lungs, which gives the breath a characteristic fruity odour. If ketones build up in the body long enough, they cause serious illness and coma (see ketoacidosis.) (09 Oct 1997) |
| acute inclusion body encephalitis | The most common acute encephalitis, caused by HSV-1; affects persons of any age; preferentially involves the inferomedial portions of the temporal lobe and the orbital portions of the frontal lobes; pathologically, severe haemorrhagic necrosis is present along with, in the acute stages, intranuclear eosinophilic inclusion bodies in the neurons and glial cells. Synonym: acute inclusion body encephalitis, herpes encephalitis. (05 Mar 2000) |
| adrenal body | See adrenal gland. (12 Dec 1998) |
| alveolar body | That portion of bone in either the maxilla or the mandible which surrounds and supports the teeth. (12 Dec 1998) |
| amygdaloid body | Almond-shaped group of basal nuclei anterior to the inferior horn of the lateral ventricle of the brain, within the temporal lobe. The amygdala is part of the limbic system. (12 Dec 1998) |