| orbital sulci | A number of irregularly disposed, variable sulci dividing the inferior or orbital surface of each frontal lobe of the cerebrum into the orbital gyri. Synonym: sulci orbitales. (05 Mar 2000) |
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| orbital surface | The surface of a bone which contributes to the walls of the orbit. The NA recognises an orbital surface on the following bones: greater wing of the sphenoid bone; the maxilla; the frontal bone; the zygomatic bone. Synonym: facies orbitalis. (05 Mar 2000) |
| orbital syndrome | <syndrome> An obsolete term referring to neoplastic tissue formation involving the apex of the orbit, causing ophthalmoplegia and optic nerve atrophy. (05 Mar 2000) |
| orbital tubercle of zygomatic bone | A small elevation on the orbital surface of the zygomatic bone, just within the orbital margin, about 1 cm below the zygomaticofrontal suture; it gives attachment to the lateral check ligament, the lateral palpebral ligament, and the suspensory ligament of the eyeball. Synonym: eminentia orbitalis ossis zygomatici, orbital eminence of zygomatic bone, Whitnall's tubercle. (05 Mar 2000) |
| orbital width | The distance between the dacryon and the farthest point on the anterior edge of the outer border of the orbit (Broca), or between the latter point and the junction of the frontolacrimal suture and the posterior edge of the lacrimal groove. (05 Mar 2000) |
| tarso-orbital | Relating to the eyelids and the orbit. (05 Mar 2000) |
| zygomatico-orbital | Relating to the zygomatic bone and the orbit. (05 Mar 2000) |
| zygomatico-orbital artery | <anatomy, artery> Origin, superficial temporal, sometimes middle temporal; distribution, orbicularis oculi muscle and portions of the orbit; anastomoses, lacrimal and palpebral branches of ophthalmic. Synonym: arteria zygomatico-orbitalis. (05 Mar 2000) |
| zygomatico-orbital foramen | The common opening on the orbital surface of the zygomatic bone of the canals transmitting the zygomaticofacial and zygomaticotemporal nerves; sometimes each of these canals has a separate opening on the orbital surface. Synonym: foramen zygomatico-orbitale. (05 Mar 2000) |
| fronto-orbital area | The cerebral cortex covering the basal surface of the frontal lobes. Synonym: fronto-orbital area. (05 Mar 2000) |
| adrenal cyst | <radiology> Same characteristics as renal cysts, but less common, thick wall, septations, calcifications suggests pseudocyst (12 Dec 1998) |
| adventitious cyst | 1. An accumulation of fluid in a cystlike loculus, but without an epithelial or other membranous lining. Synonym: adventitious cyst, false cyst. 2. A cyst whose wall is formed by a host cell and not by a parasite. 3. A mass of 50 or more Toxoplasma bradyzoites, found within a host cell, frequently in the brain; formerly called a pseudocyst, but now considered a true cyst enclosed in its own membrane within the host cell that may rupture to release particles that form new cysts, and apparently is infective to another vertebrate host. See: bradyzoite. Origin: pseudo-+ G. Kystis, bladder (05 Mar 2000) |
| allantoic cyst | Cyst occurring in a persistent portion of the urachus, presenting as an extraperitoneal mass in the umbilical region. It is characterised by abdominal pain, and fever if infected. It may rupture, leading to peritonitis, or it may drain through the umbilicus. (12 Dec 1998) |
| alveolar hydatid cyst | A hydatid cyst of a multiloculate type, usually in the liver, caused by Echinococcus multilocularis, adults of which are in foxes; larvae (alveolar hydatid) are found chiefly in microtine rodents, but also among humans such as trappers and others handling pelts of infected foxes and other carnivores; growth is by exogenous budding and is not limited by an outer laminated membrane as in the hydatid cyst from E. Granulosus; necrosis, cavitation, contiguous spread, and death usually ensue. Synonym: multilocular hydatid cyst, multiloculate hydatid cyst. (05 Mar 2000) |
| aneurysmal bone cyst | <radiology> ABC, 10 - 30 yrs, 75% before skeletal maturity, sites: long bones; also, flat bones Findings: metaphyseal if unfused, metaepiphyseal after fusion, lytic, expansile, thin, continuous rim, thin internal bony strands (12 Dec 1998) |