orbit (redirected from orbiting)

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

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or·bit (ôrbt)

n.

See orbital cavity.

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Orbit

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

Mentioned in: Eye Cancer, Eye Muscle Surgery, Maxillofacial Trauma, Mucormycosis

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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.

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orbit,

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

Orbit.

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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.

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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.

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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
roof	medial wall
1. frontal	1. maxilla
2. lesser wing of sphenoid	2. lacrimal
	3. ethmoid
	4. sphenoid
floor	lateral wall
1. maxilla	1. greater wing of sphenoid
2. zygomatic
3. palatine	2. zygomatic

Table O4 Orbital apertures
aperture	location	contents
optic canal	at the apex (in lesser sphenoid)	optic nerve ophthalmic artery sympathetic nerve fibres
superior orbital fissure	at the apex (gap between greater and lesser sphenoid)	III, IV, V, VI nerves sympathetic nerve fibres ophthalmic vein recurrent lacrimal artery
inferior orbital fissure	between lateral wall and posterior part of the floor	infraorbital 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 foramen	lateral wall	zygomatic nerve and vessels
nasolacrimal canal	medial wall (maxilla/lacrimal)	nasolacrimal duct

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ORBIT

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