The lesser wings of the sphenoid 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 ig. 1 In some animals, they remain as separate bones called orbitosphenoids.

Structure

The main features of the lesser wing are the optic canal, the anterior clinoid process, and the superior 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 The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements o ...

, the trochlear nerve, and the abducent nerve, the three branches of the ophthalmic division of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

, some filaments from the cavernous plexus of the sympathetic nervous system, the orbital branch of the

middle meningeal artery The middle meningeal artery (') is typically the third branch of the maxillary artery#First portion, first portion of the maxillary artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum t ...

, a recurrent branch from the

lacrimal artery The lacrimal artery is an artery of the Orbit (anatomy), orbit. It is a branch of the ophthalmic artery. It accompanies the lacrimal nerve along the upper border of the lateral rectus muscle, travelling forward to reach the lacrimal gland. It sup ...

to the dura mater, and the ophthalmic 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 the tentorium 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 the

internal carotid artery The internal carotid artery is an artery in the neck which supplies the anterior cerebral artery, anterior and middle cerebral artery, middle cerebral circulation. In human anatomy, the internal and external carotid artery, external carotid ari ...

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 the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

and ophthalmic artery.

Additional images

File:Gray190.png, The skull from the front. File:Slide22hhhh.JPG, Lesser wing of sphenoid bone File:Slide7jjjj.JPG, Lesser wing of sphenoid bone File:Slide2mmmm.JPG, Lesser wing of sphenoid bone File:Slide8pppp.JPG, Lesser wing of sphenoid bone

References

External links

* {{Authority control Bones of the head and neck