- Greater wing of sphenoid bone
Infobox Bone
Name = Greater wing of sphenoid bone
Latin = ala major ossis sphenoidalis
GraySubject = 35
GrayPage = 149
Caption = Figure 1:Sphenoid bone , upper surface.
Caption2 = Figure 2:Sphenoid bone , anterior and inferior surfaces.
Width = 300
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Articulations =
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DorlandsPre = a_21
DorlandsSuf = 12118035
The greater wing of the sphenoid bone, or ali-sphenoid, is a bony process of thesphenoid bone ; there is one on each side, extending from the side of the body of the sphenoid and curving upward, laterally, and backwards.tructure
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, thespine 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:
* Theforamen rotundum is a circular aperture at its anterior and medial part; it transmits themaxillary nerve .
* The foramen ovale is behind and lateral to this; it transmits themandibular nerve , theaccessory meningeal artery , and sometimes thelesser petrosal nerve .
* Thesphenoidal 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 thescaphoid fossa , and transmits a small vein from the cavernous sinus.
* Theforamen spinosum , in the posterior angle near to and in front of the spine; it is a short canal which transmits themiddle meningeal vessels and arecurrent branch from themandibular 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 thetemporal fossa , and gives attachment to thetemporalis ;
* the inferior infratemporal surface, smaller in size and concave, enters into the formation of theinfratemporal fossa , and, together with the infratemporal crest, serves as an attachment to thelateral pterygoid muscle .It is pierced by the
foramen ovale andforamen spinosum , and at its posterior part is thesphenoidal spine , which is frequently grooved on its medial surface for thechorda tympani nerve .To the sphenoidal spine are attached the
sphenomandibular ligament and thetensor 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 thepterygomaxillary 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 thefrontal bone .
* Its inferior rounded border forms the postero-lateral boundary of theinferior orbital fissure .
* Its medial sharp margin forms the lower boundary of thesuperior orbital fissure and has projecting from about its center a little tubercle which gives attachment to the inferior head of thelateral rectus muscle; at the upper part of this margin is a notch for the transmission of a recurrent branch of thelacrimal artery .
* Its lateral margin is serrated and articulates with thezygomatic bone .
* Below the medial end of the superior orbital fissure is a grooved surface, which forms the posterior wall of thepterygopalatine fossa , and is pierced by theforamen 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 theforamen lacerum , and presents the posterior aperture of thepterygoid 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 theauditory 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 thepterion .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 thesuperior orbital fissure , and laterally with the serrated margin for articulation with thezygomatic bone .
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