The greater wing of the sphenoid bone, or alisphenoid, is a bony process of the

sphenoid bone The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bon ...

, positioned in the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

behind each

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

. There is one on each side, extending from the side of the

body of the sphenoid The body of the sphenoid bone, more or less cubical in shape, is hollowed out in its interior to form two large cavities, the sphenoidal sinuses, which are separated from each other by a septum. Superior surface The superior surface of the body ...

and curving upward, laterally, and backward.

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, laterally, and backward; the posterior part of each projects as a triangular process that fits into the angle between the squamous and the petrous part of the

temporal bone The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...

and presents at its apex a downward-directed process, the

spine of sphenoid bone The sphenoidal spine (Latin: "''spina angularis''") is a downwardly directed process at the apex of the great wings of the sphenoid bone that serves as the origin of the sphenomandibular ligament. Additional images File:Spine of sphenoid bone. ...

Cerebral surface

The superior or cerebral surface of each greater wing

ig. 1 IG, Ig, or ig may refer to: Companies * IG Farben, a former German industrial conglomerate * IG Group, a UK financial services company * IG Recordings, a record label formed by the Indigo Girls, an American folk/rock duo * Production I.G, a Japa ...

forms part of the middle cranial fossa; it is deeply concave, and presents depressions for the convolutions of the

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in pr ...

of the brain. It has a number of foramina (holes) in it: * The

foramen rotundum The foramen rotundum is a circular hole in the sphenoid bone of the skull. It connects the middle cranial fossa and the pterygopalatine fossa. It allows for the passage of the maxillary nerve (V2), a branch of the trigeminal nerve. Structure T ...

is a circular aperture at its anterior and medial part; it transmits the

maxillary nerve In neuroanatomy, the maxillary nerve (V) is one of the three branches or divisions of the trigeminal nerve, the fifth (CN V) cranial nerve. It comprises the principal functions of Sense, sensation from the maxilla, nasal cavity, Sinus (anatomy ...

. * The foramen ovale is behind and lateral to this; it transmits the

mandibular nerve In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth Cranial nerves, cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve (ophthalmic nerve, maxillary nerve) which ...

, the

accessory meningeal artery Accessory may refer to: * Accessory (legal term), a person who assists a criminal In anatomy * Accessory bone * Accessory breast * Accessory kidney * Accessory muscle * Accessory nucleus, in anatomy, a cranial nerve nucleus * Accessory nerve * ...

, and sometimes the

lesser petrosal nerve The lesser petrosal nerve (also known as the small superficial petrosal nerve) is the general visceral efferent (GVE) nerve conveying pre-ganglionic parasympathetic secretomotor fibers for the parotid gland from the tympanic plexus to the otic g ...

. * The

sphenoidal emissary foramen In the base of the skull, in the great wings of the sphenoid bone, medial to the foramen ovale, a small aperture, the sphenoidal emissary foramen, may occasionally be seen (it is often absent) opposite the root of the pterygoid process. When pres ...

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 In the pterygoid processes of the sphenoid, above the pterygoid fossa is a small, oval, shallow depression, the scaphoid fossa, which gives origin to the tensor veli palatini The tensor veli palatini muscle (tensor palati or tensor muscle of t ...

, and transmits a small vein from the cavernous sinus. * The

foramen spinosum The foramen spinosum is a Foramen, small open hole in the greater wing of the sphenoid bone that gives passage to the middle meningeal artery and vein, and the meningeal branch of the mandibular nerve (sometimes it passes through the Foramen ova ...

, in the posterior angle near to and in front of the spine; it is a short canal that transmits the middle meningeal vessels and a

recurrent branch Recurrent branch may refer to: * Recurrent branch of the median nerve The recurrent branch of the median nerve is the branch of the median nerve which supplies the thenar muscles. It is also occasionally referred to as the thenar branch of the med ...

from the

. * The

foramen petrosum The lesser petrosal nerve (also known as the small superficial petrosal nerve) is the general visceral efferent (GVE) nerve conveying pre-ganglionic parasympathetic secretomotor fibers for the parotid gland from the tympanic plexus to the otic g ...

, a small occasional opening, between the foramen spinosum and foramen ovale, for transmission of the

Lateral surface

The lateral surface

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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 The temporal fossa is a fossa (shallow depression) on the side of the skull bounded by the temporal lines above, and the zygomatic arch below. Its floor is formed by the outer surfaces of four bones of the skull. The fossa is filled by the te ...

, and gives attachment to the

temporalis In anatomy, the temporalis muscle, also known as the temporal muscle, is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head that fills the temporal fossa, superior to the zygomatic ...

; * the inferior infratemporal surface, smaller in size and concave, enters into the formation of the

infratemporal fossa The infratemporal fossa is an irregularly shaped cavity that is a part of the skull. It is situated below and medial to the zygomatic arch. It is not fully enclosed by bone in all directions. It contains superficial muscles, including the lower ...

, and, together with the infratemporal crest, serves as an attachment to the

lateral pterygoid muscle The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of mastication. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid n ...

. It is pierced by the foramen ovale and

, and at its posterior part is the sphenoidal spine, which is frequently grooved on its medial surface for the

chorda tympani nerve Chorda tympani is a branch of the facial nerve that carries gustatory (taste) sensory innervation from the front of the tongue and parasympathetic ( secretomotor) innervation to the submandibular and sublingual salivary glands. Chorda tympani ...

. To the sphenoidal spine are attached the

sphenomandibular ligament The sphenomandibular ligament (internal lateral ligament) is one of the three ligaments of the temporomandibular joint. It is situated medially to - and generally separate from - the articular capsule of the joint. Superiorly, it is attached to th ...

and the

tensor veli palatini The tensor veli palatini muscle (tensor palati or tensor muscle of the velum palatinum) is a thin, triangular muscle of the head that tenses the soft palate and opens the Eustachian tube to equalise pressure in the middle ear. Structure The te ...

muscle. Medial to the anterior extremity of the infratemporal crest is a triangular process that serves to increase the attachment of the

; extending downward and medialward from this process on to the front part of the lateral pterygoid plate is a ridge that forms the anterior limit of the infratemporal surface, and, in the articulated skull, the posterior boundary of the

pterygomaxillary fissure The pterygomaxillary fissure is a fissure of the human skull. It is vertical, and descends at right angles from the medial end of the inferior orbital fissure. It is a triangular interval, formed by the divergence of the maxilla from the pterygoi ...

Orbital surface

The orbital surface of the great wing

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 In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...

. * Its inferior rounded border forms the postero-lateral boundary of the

inferior orbital fissure The inferior orbital fissure is a gap between the Greater wing of sphenoid bone, greater wing of sphenoid bone, and the maxilla. It connects the Orbit (anatomy), orbit (anteriorly) with the infratemporal fossa and pterygopalatine fossa (posterio ...

. * Its medial sharp margin forms the lower boundary of the

superior orbital fissure The superior orbital fissure is a foramen or cleft of the skull between the lesser and greater wings of the sphenoid bone. It gives passage to multiple structures, including the oculomotor nerve, trochlear nerve, ophthalmic nerve, abducens nerve ...

and has projecting from about its center a little tubercle that gives attachment to the inferior head of the

lateral rectus The lateral rectus muscle is a muscle on the lateral side of the eye in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifi ...

muscle; at the upper part of this margin is a notch for the transmission of a recurrent branch of 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 ...

. * Its lateral margin is serrated and articulates with the

zygomatic bone In the human skull, the zygomatic bone (from ), also called cheekbone or malar bone, is a paired irregular bone, situated at the upper and lateral part of the face and forming part of the lateral wall and floor of the orbit, of the temporal fos ...

. * Below the medial end of the superior orbital fissure is a grooved surface, which forms the posterior wall of the

pterygopalatine fossa In human anatomy, the pterygopalatine fossa (sphenopalatine fossa) is a fossa in the skull. A human skull contains two pterygopalatine fossae—one on the left side, and another on the right side. Each fossa is a cone-shaped paired depression dee ...

, and is pierced by the

Margin

Commencing from behind

that portion of the circumference of the great wing that extends from the body to the spine is irregular. * Its ''medial half'' forms the anterior boundary of the

foramen lacerum The foramen lacerum () is a triangular hole in the base of the skull. It is located between the sphenoid bone, the apex of the petrous part of the temporal bone, and the basilar part of the occipital bone. Structure The foramen lacerum () is a ...

, and presents the posterior aperture of the

pterygoid canal The pterygoid canal (also vidian canal) is a passage in the sphenoid bone of the skull leading from just anterior to the foramen lacerum in the middle cranial fossa to the pterygopalatine fossa. It transmits the nerve of pterygoid canal (Vidi ...

for the passage of the corresponding nerve and artery. * Its ''lateral half'' articulates, by means of a

synchondrosis A synchondrosis (or primary cartilaginous joint) is a type of cartilaginous joint where hyaline cartilage completely joins together two bones. Synchondroses are different from symphyses (secondary cartilaginous joints), which are formed of fibroca ...

, 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 The Eustachian tube (), also called the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. In adult humans, the Eustachian tube is approximately long and in diameter. It ...

. 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

. 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 The parietal bones ( ) are two bones in the skull which, when joined at a fibrous joint known as a cranial suture, form the sides and roof of the neurocranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four bord ...

; this region is named the

pterion The pterion is the region where the frontal, parietal, temporal, and sphenoid bones join. It is located on the side of the skull, just behind the temple. It is also considered to be the weakest part of the skull, which makes it clinically si ...

. Medial to this is a triangular, serrated surface, for articulation with the

; this surface is continuous medially with the sharp edge that forms the lower boundary of the

, and laterally with the serrated margin for articulation with the

Development

The greater wing of the sphenoid bone starts as a separate bone, and is still separate at birth in humans.

Function

The

assists with the formation of the base and the sides of the skull, and the floors and walls of the orbits. It is the site of attachment for most of the muscles of

mastication Chewing or mastication is the process by which food is comminution, crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods. During the mast ...

. Many foramina and fissures are located in the sphenoid that carry nerves and blood vessels of the head and neck, such as the

(with

ophthalmic nerve The ophthalmic nerve (CN V1) is a sensory nerve of the head. It is one of three divisions of the trigeminal nerve (CN V), a cranial nerve. It has three major branches which provide sensory innervation to the eye, and the skin of the upper face ...

(with

) and foramen ovale (with

Clinical significance

In patients with

neurofibromatosis type 1 Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, e ...

, malformation of the sphenoid bone wings may occur, due to aberrant cell development. This can ultimately lead to blindness if left untreated.

In other animals

In many mammals, e.g. the

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...

, the greater wing of the sphenoid bone stays through life a separate bone called the alisphenoid.

Additional images

File:Orbital_bones.png, The seven bones that articulate to form the orbit. File:Gray187.png, Base of skull. Inferior surface. File:Gray189.png, Left infratemporal fossa. File:Gray190.png, The skull from the front. File:Gray310.png, Articulation of the mandible. Medial aspect. File:Gray889.png, Muscles of the right orbit. File:Slide24hhhh.JPG, Greater wing of sphenoid bone File:Slide8jjjj.JPG, Greater wing of sphenoid bone File:Slide1mmmm.JPG, Greater wing of sphenoid bone File:Slide7nnnn.JPG, Greater wing of sphenoid bone File:Slide3pppp.JPG, Greater wing of sphenoid bone

External links

* *

References

{{Authority control Bones of the head and neck