| orbital axis | The line from the centre of the optic foramen (apex of orbit) extending anteriorly, laterally, and inferiorly to the middle of the orbital opening. (05 Mar 2000) |
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| orbital branch of middle meningeal artery | <anatomy, artery> Branch of middle meningeal artery traversing superior orbital fissure and running toward lacrimal gland. See: anastomotic branch of middle meningeal artery to lacrimal artery. Synonym: ramus orbitalis arteriae meningeae mediae. (05 Mar 2000) |
| orbital branch of pterygopalatine ganglion | Branches of pterygopalatine ganglion traversing inferior orbital fissure, distributed in orbit to periorbita and mucosa of ethmoidal and sphenoidal sinuses. Synonym: ramus orbitalis ganglii pterygopalatini. (05 Mar 2000) |
| orbital cavity | 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) |
| orbital decompression | Removal of a portion of the bony orbit, usually superior (Naffziger operation), lateral (Kronlein operation), or inferior (Ogura operation). (05 Mar 2000) |
| orbital diseases | Diseases of the bony orbit and contents except the eyeball. (12 Dec 1998) |
| orbital eminence 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 exenteration | Removal of the entire contents of the orbit. (05 Mar 2000) |
| orbital fasciae | The fascial layers in the orbit consisting of periorbita, septum orbitale, fascia muscularis musculorum bulbi, and vagina bulbi. Synonym: fasciae orbitales. (05 Mar 2000) |
| orbital fractures | Fractures of the bones in the orbit, which include parts of the frontal, ethmoidal, lacrimal, and sphenoid bones and the maxilla and zygoma. (12 Dec 1998) |
| orbital gyri | A number of small, irregular convolutions occupying the concave inferior surface of each frontal lobe of the cerebrum. Synonym: gyri orbitales. (05 Mar 2000) |
| orbital hernia | Displacement of orbital fat through a defect in the orbital septum or Tenon's capsule into the subcutaneous tissues of the eyelid or subconjunctivally. (05 Mar 2000) |
| orbital implant | The glass, plastic, or metal device placed in the muscle cone after enucleation of an eye. (05 Mar 2000) |
| orbital index | Relation of the height of the orbit to its width: (orbital height × 100)/orbital width. (05 Mar 2000) |
| orbital lamina of ethmoid bone | A thin plate of ethmoid bone forming part of the medial wall of the orbit and the lateral wall for the ethmoidal labyrinth. Synonym: lamina orbitalis ossis ethmoidalis, lamina papyracea, orbital lamina of ethmoid bone, orbital layer of ethmoid bone, orbital plate, paper plate, papyraceous plate. (05 Mar 2000) |