What is an alisphenoid?

Name the bones that compose the orbit of the eye?

The bones that form the orbit of the eye are the ethmoid, lacrimal, maxilla, frontal, sphenoid, zygoma, palatine The orbits are pyramidal, bony cavities in the facial skeleton with their bases (orbital openings) directed anterolaterally and their apices, posteromedially. The orbits contain and protect the eyeballs and their muscles, nerves, and vessels, together with most of the lacrimal apparatus. All space in the orbits not occupied by structures is filled with orbital fat. The fat forms a matrix in which the structures of the orbit are embedded. The orbit has a base, four walls, and an apex: The superior wall (roof) is approximately horizontal and is formed mainly by the orbital part of the frontal bone, which separates the orbital cavity from the anterior cranial fossa. Near the apex of the orbit, the superior wall is formed by the lesser wing of the sphenoid. Anterolaterally the lacrimal gland occupies the fossa for the lacrimal gland (lacrimal fossa) in the orbital part of the frontal bone. The medial wall is formed by the ethmoid bone, along with contributions from the frontal, lacrimal, and sphenoid bones. Anteriorly, the medial wall is indented by the lacrimal groove and fossa for the lacrimal sac. The bone forming the medial wall is paper thin, and the ethmoid air cells are often visible through the bone of a dried cranium. The lateral wall is formed by the frontal process of the zygomatic bone and the greater wing of the sphenoid. This is the strongest and thickest wall, which is important because it is most exposed and vulnerable to direct trauma. Its posterior part separates the orbit from the temporal lobes of the brain and middle cranial fossae. The inferior wall (floor) is formed mainly by the maxilla and partly by the zygomatic and palatine bones. The thin inferior wall is shared by the orbit superiorly and the maxillary sinus inferiorly. It slants inferiorly from the apex to the inferior orbital margin. The inferior wall is demarcated from the lateral wall by the inferior orbital fissure. The apex of the orbit is at the optic canal in the lesser wing of the sphenoid, just medial to the superior orbital fissure. The bones forming the orbit are lined with periorbita (periosteum of the orbit). The periorbita is continuous at the optic canal and superior orbital fissure with the periosteal layer of dura mater. The periorbita is also continuous over the orbital margins and through the inferior orbital fissure with the periosteum covering the external surface of the cranium (pericranium) and with the orbital septa at the orbital margins, with the fascial sheaths of the extraocular muscles, and with orbital fascia that forms the fascial sheath of the eyeball.

What is an alisphenoid?

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Name the bones that compose the orbit of the eye?

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