| aperture of orbit | The somewhat quadrangular anterior entrance to the orbit which forms the base of the pyramid-shaped orbital cavity. It is bounded by the sharp supra-, infra-, and lateral orbital margins and a less obvious medial margin on each side of the upper nose. Synonym: aditus orbitae, aperture of orbit. (05 Mar 2000) |
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| apex of orbit | The posterior part of the orbit into which the optic canal opens; forms the tip of the pyramidal-shaped space. (05 Mar 2000) |
| 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) |
| 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) |
| fat body of orbit | The mass of fat contained in the orbit that contributes to the support of the eyeball. Synonym: corpus adiposum orbitae, fat body of orbit. (05 Mar 2000) |
| 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) |
| abbreviated injury scale | Classification system for assessing impact injury severity developed and published by the american association for automotive medicine. It is the system of choice for coding single injuries and is the foundation for methods assessing multiple injuries or for assessing cumulative effects of more than one injury. These include maximum ais (mais), injury severity score (iss), and probability of death score (pods). (12 Dec 1998) |
| axillary nerve injury | <neurology> A condition involving dysfunction of the axillary nerve which normally supplies the deltoid and teres minor muscles and sensation to the lateral aspect of the shoulder. This condition is a type of peripheral neuropathy that may manifest as the result of a variety of disease processes or injuries. Conditions associated with axillary nerve dysfunction include mononeuritis multiplex, fracture of the humerus, abduction injury to the shoulder, pressure to the armpit from a cast, splint or crutches. Symptoms include numbness over the outer portion of the shoulder, shoulder weakness and difficulty lifting arm or objects over your head. An EMG, nerve conduction study or muscle biopsy can be helpful in making the diagnosis. Recovery is generally spontaneous if the underlying cause can be corrected and shoulder mobility is preserved. Corticosteroid injections may be indicated in some instances. (02 Jan 1998) |