orbit


Also found in: Dictionary, Thesaurus, Legal, Acronyms, Idioms, Encyclopedia, Wikipedia.
Related to orbit: Priceline

orbit

 [or´bit]
1. the bony cavity containing the eyeball and its associated muscles, vessels, and nerves; the ethmoid, frontal, lacrimal, nasal, palatine, sphenoid, and zygomatic bones and the maxilla contribute to its formation.
2. the path of an electron around the nucleus of an atom. adj., adj or´bital.

or·bit

(ōr'bit), [TA]
The bony cavity containing the eyeball and its adnexa; it is formed of parts of seven bones: the frontal, maxillary, sphenoid, lacrimal, zygomatic, ethmoid, and palatine.
Synonym(s): orbita [TA], eye socket

orbit

/or·bit/ (or´bit) the bony cavity containing the eyeball and its associated muscles, vessels, and nerves.or´bital

orbit

(ôr′bĭt)

orbit

[ôr′bit]
Etymology: L, orbita, wheel track
one of a pair of bony, conical cavities in the skull that accommodate the eyeballs and associated structures, such as the eye muscles, nerves, and blood vessels. The medial walls of the orbits are approximately parallel with each other and with the middle line, but the lateral walls diverge widely. The roof of each orbit is formed by the orbital plate of the frontal bone and the small wing of the sphenoid bones. The openings that communicate with each orbit are the optic foramen, the superior and the inferior orbital fissures, the supraorbital foramen, the infraorbital canal, the anterior and posterior ethmoidal foramina, the zygomatic foramen, and the canal for the nasolacrimal duct. orbital, adj.
enlarge picture
Bones of the orbit

ORBIT

Cardiology A clinical trial Oral Glycoprotein IIb/IIIa receptor Blockade to Inhibit Thrombosis

or·bit

(ōr'bit) [TA]
The bony cavity containing the eyeball and its adnexa; it is formed of parts of the frontal, maxillary, sphenoid, lacrimal, zygomatic, ethmoid, and palatine bones.
Synonym(s): orbita [TA] , orbital cavity.

orbit

The bony cavern in the skull that contains the eyeball and OPTIC NERVE, the muscles that move the eye, the LACRIMAL GLAND, a quantity of fat and various arteries, veins and nerves.

orbit

the body cavity or socket in the vertebrate skull containing the eyeball.

Orbit

The cavity in the skull containing the eye-ball; formed from seven bones: frontal, maxillary, sphenoid, lacrimal, zygomatic, ethmoid, and palatine.

orbit,

n hollow space where the eyeball and its muscles, nerves, and blood vessels are located.
Enlarge picture
Orbit.

orbit 

A rigid bony cavity in the skull which contains an eyeball, orbital fat, the extraocular muscles, the optic nerve, nerves and blood vessels, lacrimal system and fibrous tissue of various kinds. This packing serves to keep the eyeball reasonably well fixed in place as it rotates. The orbital cavity has the approximate form of a pyramid. The walls of the orbital cavity are formed by seven bones. The medial wall of the orbit consists of: (1) the frontal process of the maxilla (maxillary); (2) the lacrimal bone; (3) the lamina papyracea of the ethmoid; and (4) a small part of the body of the sphenoid. The floor of the orbit consists of: (1) the orbital plate of the maxilla; (2) the orbital surface of the zygomatic (malar) bone and (3) the orbital process of the palatine bone. The lateral wall of the orbit consists of (1) the orbital surface of the greater wing of the sphenoid, and (2) the orbital surface of the zygomatic. The roof of the orbit is made up mainly by the frontal bone and behind this by the lesser wing of the sphenoid. The orbit is lined with a membrane of tissue called the periorbita (or orbital periosteum) which extends to the orbital margin (anterior rim of the orbit) where it becomes continuous with the periosteum covering the facial bones. The periorbita is loosely attached to the bones except at sutures, foramina and the orbital margin where it is firmly attached. The bones are much thicker at the margin (rim) than they are along the walls of the orbital cavity. There are many apertures and gaps in the orbit through which blood vessels and nerves pass (see Table O4). See orbital axis; optic canal; inferior orbital fissure; superior orbital fissure; orbital fracture; cavernous haemangioma; lamina papyracea.
Table O3 Bones forming the walls of the orbit
roofmedial wall
1. frontal1. maxilla
2. lesser wing of sphenoid2. lacrimal
3. ethmoid
4. sphenoid
floorlateral wall
1. maxilla1. greater wing of sphenoid
2. zygomatic
3. palatine2. zygomatic

Table O4 Orbital apertures
aperturelocationcontents
optic canalat the apex (in lesser sphenoid)optic nerve
ophthalmic artery
sympathetic nerve fibres
superior orbital fissureat the apex (gap between greater and lesser sphenoid)III, IV, V, VI nerves
sympathetic nerve fibres
ophthalmic vein
recurrent lacrimal artery
inferior orbital fissurebetween lateral wall and posterior part of the floorinfraorbital nerve
zygomatic nerve
branch of inferior ophthalmic vein
nerve fibres from the
pterygopalatine (sphenopalatine)
ganglion to orbital periosteum
ethmoidal foramina (anterior and post.)medial wall (frontal/ethmoidal suture)ethmoidal vessels
ethmoidal nerve/external nasal nerve
zygomatic foramenlateral wallzygomatic nerve and vessels
nasolacrimal canalmedial wall (maxilla/lacrimal)nasolacrimal duct

or·bit

(ōr'bit) [TA]
Bony cavity containing eyeball and its adnexa.

orbit,

n 1. in chemistry, refers to the movement of an electron around an atom's nucleus.
2. the bony socket that contains the eyeball and all its supporting structures.

orbit

1. the bony cavity containing the eyeball and its associated muscles, vessels and nerves; the ethmoid, frontal, lacrimal, nasal, palatine, sphenoid and zygomatic bones and the maxilla contribute to its formation.
2. the path of an electron around the nucleus of an atom.
References in classic literature ?
If this planet has any atmosphere at all, it is one of no great density, and its orbit being without our own, we can easily trace on its surface the outlines of seas and continents.
Captain Doane worked hard, pursuing the sun in its daily course through the sky, by the equation of time correcting its aberrations due to the earth's swinging around the great circle of its orbit, and charting Sumner lines innumerable, working assumed latitudes for position until his head grew dizzy.
approach to truth: the perigee of his eccentric orbit.
The air, unlit before, glows with the light of her golden crown, and her rays beam clear, whensoever bright Selene having bathed her lovely body in the waters of Ocean, and donned her far-gleaming, shining team, drives on her long-maned horses at full speed, at eventime in the mid-month: then her great orbit is full and then her beams shine brightest as she increases.
But, inasmuch as it is equally necessary to take into account the deviation which the rotary motion of the earth will impart to the shot, and as the shot cannot reach the moon until after a deviation equal to 16 radii of the earth, which, calculated upon the moon's orbit, are equal to about eleven degrees, it becomes necessary to add these eleven degrees to those which express the retardation of the moon just mentioned: that is to say, in round numbers, about sixty-four degrees.
Belfast and Maston-- that it had deviated from its course from some unknown cause, and had not reached its destination; but that it had passed near enough to be retained by the lunar attraction; that its rectilinear movement had been changed to a circular one, and that following an elliptical orbit round the star of night it had become its satellite.
As if the sun should stop when he had kindled his fires up to the splendor of a moon or a star of the sixth magnitude, and go about like a Robin Goodfellow, peeping in at every cottage window, inspiring lunatics, and tainting meats, and making darkness visible, instead of steadily increasing his genial heat and beneficence till he is of such brightness that no mortal can look him in the face, and then, and in the meanwhile too, going about the world in his own orbit, doing it good, or rather, as a truer philosophy has discovered, the world going about him getting good.
The other terror that scares us from self-trust is our consistency; a reverence for our past act or word because the eyes of others have no other data for computing our orbit than our past acts, and we are loath to disappoint them.
I seemed swinging in a mighty rhythm through orbit vastness.
Around soothsayers and astrologers hath hitherto revolved the orbit of this illusion.
The mysterious light appeared more brilliantly than before, dancing, to all appearance, up and down the lane, crossing from side to side, and moving in an orbit as eccentric as comets themselves.
First, the whales forming the margin of our lake began to crowd a little, and tumble against each other, as if lifted by half spent billows from afar; then the lake itself began faintly to heave and swell; the submarine bridal-chambers and nurseries vanished; in more and more contracting orbits the whales in the more central circles began to swim in thickening clusters.