- Lesser wing of sphenoid bone
Infobox Bone
Name = PAGENAME
Latin = alæ parvæ
GraySubject = 35
GrayPage = 151
Caption = Figure 1:Sphenoid bone , upper surface.
Caption2 = Figure 2:Sphenoid bone , anterior and inferior surfaces.
Width = 300
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The lesser wings of thesphenoid or orbito-sphenoids are two thin triangular plates, which arise from the upper and anterior parts of the body, and, projecting lateralward, end in sharp points [Fig. 1] .tructure
The main features of the lesser wing are the
optic canal , theanterior clinoid process , and thesuperior orbital fissure .Surfaces
The superior surface of each is flat, and supports part of the frontal lobe of the brain. The inferior surface forms the back part of the roof of the orbit, and the upper boundary of the superior orbital fissure.
This fissure is of a triangular form, and leads from the cavity of the cranium into that of the orbit: it is bounded medially by the body; above, by the small wing; below, by the medial margin of the orbital surface of the great wing; and is completed laterally by the frontal bone.
It transmits the
oculomotor nerve , thetrochlear nerve , and theabducent nerve, the three branches of the ophthalmic division of thetrigeminal nerve , some filaments from thecavernous plexus of the sympathetic nervous system, the orbital branch of themiddle meningeal artery , a recurrent branch from thelacrimal artery to thedura mater , and theophthalmic vein .Borders
The anterior border is serrated for articulation with the
frontal bone .The posterior border, smooth and rounded, is received into the lateral fissure of the brain; the medial end of this border forms the
anterior clinoid process , which gives attachment to thetentorium cerebelli ; it is sometimes joined to the middle clinoid process by a spicule of bone, and when this occurs the termination of the groove for theinternal carotid artery is converted into a foramen (carotico-clinoid).The lesser wing is connected to the body by two roots, the upper thin and flat, the lower thick and triangular; between the two roots is the
optic foramen , for the transmission of theoptic nerve andophthalmic artery .
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