Greater wing of sphenoid bone
4380012
106595518
2007-02-08T16:08:44Z
Arcadian
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{{Infobox Bone |
Name = Greater wing of sphenoid bone |
Latin = ala major ossis sphenoidalis |
GraySubject = 35 |
GrayPage = 149 |
Image = Gray145.png |
Caption = Figure 1: [[Sphenoid bone]], upper surface. |
Image2 = Gray146.png |
Caption2 = Figure 2: [[Sphenoid bone]], anterior and inferior surfaces. |
Width = 300 |
MusclesOrigins = |
MusclesInsertions = |
Articulations = |
MeshName = |
MeshNumber = |
DorlandsPre = a_21 |
DorlandsSuf = 12118035 |
}}
<!-- Editing note: the substructures (listed in Terminologia Anatomica) belonging to this structure are in bold where they are defined-->
The '''greater wing of the sphenoid bone''', or '''ali-sphenoid''', is a bony process of the [[sphenoid bone]]; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backwards.
==Structure==
The greater wings of the sphenoid are two strong processes of bone, which arise from the sides of the body, and are curved upward, lateralward, and backward; the posterior part of each projects as a triangular process which fits into the angle between the squamous and the petrous part of the [[temporal bone]] and presents at its apex a downwardly directed process, the [[spine of sphenoid bone]].
==== Cerebral surface ====
The '''superior''' or '''cerebral surface''' of each greater wing [Fig. 1] forms part of the middle cranial fossa; it is deeply concave, and presents depressions for the convolutions of the [[temporal lobe]] of the brain. It has a number of foramina (holes) in it:
* The [[foramen rotundum]] is a circular aperture at its anterior and medial part; it transmits the [[maxillary nerve]].
* The [[foramen ovale (skull)|foramen ovale]] is behind and lateral to this; it transmits the [[mandibular nerve]], the [[accessory meningeal artery]], and sometimes the [[lesser petrosal nerve]].
* The [[sphenoidal emissary foramen]] is occasionally present; it is a small aperture medial to the foramen ovale, opposite the root of the pterygoid process; it opens below near the [[scaphoid fossa]], and transmits a small vein from the cavernous sinus.
* The [[foramen spinosum]], in the posterior angle near to and in front of the spine; it is a short canal which transmits the [[middle meningeal vessels]] and a [[recurrent branch]] from the [[mandibular nerve]].
==== Lateral surface ====
The '''lateral surface''' [Fig. 2] is convex, and divided by a transverse ridge, the '''infratemporal crest''', into two portions.
* The superior '''temporal surface''', convex from above downward, concave from before backward, forms a part of the [[temporal fossa]], and gives attachment to the [[temporalis]];
* the inferior '''infratemporal surface''', smaller in size and concave, enters into the formation of the [[infratemporal fossa]], and, together with the infratemporal crest, serves as an attachment to the [[lateral pterygoid muscle]].
It is pierced by the [[foramen ovale]] and [[foramen spinosum]], and at its posterior part is the [[sphenoidal spine]], which is frequently grooved on its medial surface for the [[chorda tympani nerve]].
To the sphenoidal spine are attached the [[sphenomandibular ligament]] and the [[tensor veli palatini]] muscle.
Medial to the anterior extremity of the infratemporal crest is a triangular process which serves to increase the attachment of the [[lateral pterygoid muscle]]; extending downward and medialward from this process on to the front part of the lateral pterygoid plate is a ridge which forms the anterior limit of the infratemporal surface, and, in the articulated skull, the posterior boundary of the [[pterygomaxillary fissure]].
==== Orbital surface ====
The '''orbital surface''' of the great wing [Fig. 2], smooth, and quadrilateral in shape, is directed forward and medially and forms the posterior part of the lateral wall of the orbit.
* Its upper serrated edge articulates with the orbital plate of the [[frontal bone]].
* Its inferior rounded border forms the postero-lateral boundary of the [[inferior orbital fissure]].
* Its medial sharp margin forms the lower boundary of the [[superior orbital fissure]] and has projecting from about its center a little tubercle which gives attachment to the inferior head of the [[lateral rectus]] muscle; at the upper part of this margin is a notch for the transmission of a recurrent branch of the [[lacrimal artery]].
* Its lateral margin is serrated and articulates with the [[zygomatic bone]].
* Below the medial end of the superior orbital fissure is a grooved surface, which forms the posterior wall of the [[pterygopalatine fossa]], and is pierced by the [[foramen rotundum]].
=== Margin ===
Commencing from behind [Fig. 2], that portion of the circumference of the great wing which extends from the body to the spine is irregular.
* Its ''medial half'' forms the anterior boundary of the [[foramen lacerum]], and presents the posterior aperture of the [[pterygoid canal]] for the passage of the corresponding nerve and artery.
* Its ''lateral half'' articulates, by means of a [[synchondrosis]], with the petrous portion of the temporal, and between the two bones on the under surface of the skull, is a furrow, the '''sulcus of the auditory tube''', for the lodgement of the cartilaginous part of the [[auditory tube]].
In front of the spine the circumference presents a concave, serrated edge, bevelled at the expense of the inner table below, and of the outer table above, for articulation with the squamous part of the [[temporal bone]].
At the tip of the great wing is a triangular portion, bevelled at the expense of the internal surface, for articulation with the sphenoidal angle of the [[parietal bone]]; this region is named the [[pterion]].
Medial to this is a triangular, serrated surface, for articulation with the [[frontal bone]]; this surface is continuous medially with the sharp edge that forms the lower boundary of the [[superior orbital fissure]], and laterally with the serrated margin for articulation with the [[zygomatic bone]].
==Additional images==
<gallery>
Image:Orbital_bones.png|The seven bones which articulate to form the orbit.
Image:Gray187.png|Base of skull. Inferior surface.
Image:Gray189.png|Left infratemporal fossa.
Image:Gray190.png|The skull from the front.
Image:Gray310.png|Articulation of the mandible. Medial aspect.
Image:Gray889.png|Muscles of the right orbit.
</gallery>
==External links==
* {{RocheLexicon|34256.000-1}}
* {{RocheLexicon|34257.000-1}}
{{Gray's}}
{{Skull}}