The greater wing of the sphenoid bone is a broad, curved plate of bone that forms most of the back wall of each eye socket and a large part of the floor beneath the brain’s temporal lobe. It sits on either side of the sphenoid’s central body, stretching outward and upward like the wings of a bat, and it is pierced by several openings that channel critical nerves and blood vessels between the brain and the face.1PubMed. Anatomy and Diseases of the Greater Wings of the Sphenoid Bone Despite being buried deep in the skull, this structure shows up in an impressive range of clinical scenarios, from temple fractures to orbital tumors to rare genetic conditions that cause the bone to fail to form at all.
Where It Sits and What It Touches
The sphenoid bone as a whole is sometimes compared to a butterfly or a wasp viewed head-on, with a compact central body and paired wings on each side. The greater wings are the larger pair. Each one sweeps laterally from the body and contributes to three different regions of the skull at once. On the inside, the smooth, concave upper surface cradles the temporal lobe of the brain, forming the front and middle parts of the middle cranial fossa. On the outside, the bone’s lateral face is the flat area you can feel at your temple, just behind the eye. And facing forward, its orbital surface makes up nearly all of the back wall of the eye socket.2PubMed. Anatomy and Diseases of the Greater Wings of the Sphenoid Bone
This three-way contribution matters because it means a single pathology affecting the greater wing can produce symptoms in the brain, the eye, and the face simultaneously. A tumor growing within the bone, for instance, can push into the orbit from behind while also compressing the temporal lobe from below.
The Pterion and Why It Matters
At the temple, the greater wing meets three other bones: the frontal bone of the forehead, the parietal bone on the side of the skull, and the squamous part of the temporal bone. These four bones converge in an H-shaped junction of sutures called the pterion.3PubMed Central. Analysis of the Variations in the Morphology, Topography of the Pterion, and Their Implications in Neurosurgery The pterion is one of the thinnest spots on the entire skull, which is why a blow to the temple can be so dangerous. Running just beneath it is a groove for the middle meningeal artery, the main blood supply to the outer membrane covering the brain. A fracture at the pterion can tear that artery and lead to an epidural hematoma, a life-threatening bleed between the skull and the brain’s protective lining.
Cadaveric studies have measured the distance from the center of the pterion to the groove for the middle meningeal artery at roughly 12 mm on average, though the distance varies depending on the pterion’s shape.4International Journal of Drug Delivery Technology. Morphometric study of pterion and its relation with middle meningeal artery in dry human skulls Some pterion configurations bring the artery closer to the surface, which increases the surgical risk during craniotomies performed in this area.5PubMed. Surgical anatomy of the pterion and its relationship to the middle meningeal artery in optimizing pterional craniotomies Neurosurgeons performing a pterional craniotomy, one of the most common approaches for accessing aneurysms and tumors at the skull base, rely on detailed knowledge of these measurements to avoid injuring the artery during the bone cut.
Openings in the Greater Wing
One of the most functionally important features of the greater wing is the set of foramina, or openings, that punch through it. Each transmits specific nerves and blood vessels between the interior of the skull and the structures of the face, jaw, and orbit. Three of these openings are especially significant.
- Foramen rotundum: This opening sits near the front of the greater wing at the floor of the middle cranial fossa. The maxillary nerve, the second major branch of the trigeminal nerve, passes through it on its way to supply sensation to the midface, upper teeth, and palate.6The Egyptian Journal of Otolaryngology. Radiological anatomy of foramen rotundum and its surgical implications Recent work suggests this opening often behaves more like a short canal than a simple hole, with measurable depth and considerable variability from person to person and even from one side of the skull to the other.7PubMed Central. Foramen rotundum versus canal of the maxillary verve
- Foramen ovale: Located in the posterior part of the greater wing, this larger, oval-shaped opening transmits the mandibular nerve, the third branch of the trigeminal, which controls the muscles of chewing and provides sensation to the lower jaw.8PubMed Central. An Anatomical Study on the Foramen Ovale and the Foramen Spinosum It is also the access point for a needle procedure used to treat trigeminal neuralgia, a condition involving severe facial pain.
- Foramen spinosum: Sitting just behind and to the side of the foramen ovale, this small opening carries the middle meningeal artery into the skull to supply the meninges. Its proximity to the foramen ovale is another reason the posterior greater wing is a high-stakes zone during surgery.
The foramen rotundum deserves extra mention because nasopharyngeal cancers and other skull-base malignancies can invade through it, using the channel as a corridor from the back of the nose into the middle cranial fossa.9The Egyptian Journal of Otolaryngology. Radiological anatomy of foramen rotundum and its surgical implications Radiologists evaluating these tumors look carefully at the foramen rotundum on imaging for signs of widening or bony erosion, which indicate the cancer has spread along the nerve pathway.
Anatomical variants in these openings are more common than many clinicians realize. Case reports have documented a doubled foramen rotundum, where the maxillary nerve splits into two trunks separated by a thin plate of bone within the greater wing before reuniting on the other side.10PubMed. Doubled foramen rotundum and maxillary nerve fenestration Variants like these can complicate procedures that rely on passing instruments through or near the foramen.
The Superior Orbital Fissure
Between the greater wing and its smaller neighbor, the lesser wing of the sphenoid, is a narrow, comma-shaped gap called the superior orbital fissure. This slit sits at the very back of the eye socket and serves as the main corridor for the nerves that move the eye. The oculomotor, trochlear, and abducens nerves (cranial nerves III, IV, and VI) all pass through it, as does the ophthalmic branch of the trigeminal nerve, which carries sensation from the forehead and upper eyelid.11PubMed. Microsurgical anatomy of the superior orbital fissure
When something compresses or injures these nerves within the fissure, the result is superior orbital fissure syndrome: the eye becomes paralyzed, the upper eyelid droops, and sensation over the forehead is lost. A displaced fracture of the greater wing can push bone fragments directly into the fissure, producing this syndrome. One reported case involved a teenager whose sphenoid wing fracture initially caused only limited eye movement, but by five days after the injury, progressive swelling had compressed the nerves enough to cause complete paralysis of all eye movements.12PubMed Central. Successful Decompression and Reduction of Displaced Sphenoid Wing Fracture into the Superior Orbital Fissure Causing Complete Ophthalmoplegia Secondary to Compression of Cranial Nerves III, IV, and VI Surgical decompression of the fissure can reverse the nerve damage if it is performed before the compression becomes permanent.
How the Greater Wing Develops
The sphenoid bone is one of the most developmentally complicated bones in the body. It does not form from a single piece of cartilage or a single center of bone growth. Instead, it arises from multiple cartilaginous precursors and forms through two different processes: endochondral ossification, where cartilage is gradually replaced by bone, and intramembranous ossification, where bone forms directly within a membrane of connective tissue without a cartilage stage.13PubMed Central. The Developing Human Sphenoid Bone: Linking Embryological Development to Adult Morphology
The greater wing is predominantly a product of intramembranous ossification. Studies of human embryos and fetuses have shown that most of the greater wing, including the parts containing the foramen rotundum and foramen ovale, originates from membranous bones that develop in connection with cartilaginous precursors at the skull base.14PubMed Central. Association between the developing sphenoid and adult morphology This dual origin helps explain why the greater wing can be affected by such a range of developmental conditions. A problem in cartilage-to-bone conversion at the skull base can distort the wing’s inner surface, while a problem in membrane bone formation can affect the flat, shield-like outer portions.
The signaling pathways that guide this development are still being mapped. Research in mouse models has shown that disrupting Wnt/beta-catenin signaling, a molecular pathway important in many tissues throughout the body, delays the maturation of cartilage cells at the growth plates of the skull base.15PubMed. Wnt/beta-catenin signaling regulates cranial base development and growth Separately, loss of Sonic Hedgehog signaling in mice produces a persistent hole in the sphenoid body, premature closure of growth plates within the sphenoid, and a shortened skull base overall.16PubMed Central. Impact of Sonic Hedgehog-dependent sphenoid bone defect on craniofacial growth These findings are from animal models and cannot be mapped directly onto human disease, but they underscore how sensitive the sphenoid is to disruptions during early development.
Sphenoid Wing Dysplasia and Neurofibromatosis
One of the most recognizable conditions involving the greater wing is sphenoid wing dysplasia, in which the bone fails to develop fully or is partially absent. This leaves a gap between the brain and the eye socket. In severe cases, the temporal lobe can herniate forward through the defect and push the eye outward, producing a pulsating bulge of the eyeball that moves with each heartbeat. This dramatic sign, called pulsatile exophthalmos, occurs because the brain’s normal pulsations are no longer blocked by solid bone.
Sphenoid wing dysplasia is strongly associated with neurofibromatosis type 1 (NF1), a genetic disorder caused by mutations in the neurofibromin gene. Not everyone with NF1 develops the bone defect, but when it occurs, it is often one of the disease’s more striking features. A case study documented pulsatile exophthalmos as a presenting sign of NF1, highlighting the importance of checking for the genetic condition when this unusual eye finding is discovered.17PubMed. Anatomy and Diseases of the Greater Wings of the Sphenoid Bone Management typically involves reconstructing the orbital wall with a bone graft or mesh implant to re-establish the barrier between the brain and the orbit.
Sphenoid Wing Meningiomas
Meningiomas are slow-growing tumors that arise from the membranes covering the brain. When they develop along the sphenoid wing, they tend to produce a distinctive pattern. Rather than forming a round mass, sphenoid wing meningiomas often grow flat along the bone surface in a sheet-like fashion described as “en plaque.” They also invade the bone itself, causing it to thicken and become abnormally dense, a process called hyperostosis. The thickened bone can be the most prominent feature on imaging, sometimes dwarfing the soft-tissue tumor component.18PubMed. Management of bone-invasive, hyperostotic sphenoid wing meningiomas
The clinical picture depends on which part of the wing is involved. A meningioma on the inner (medial) portion, near the superior orbital fissure, can compress the eye-movement nerves and produce double vision or a drooping eyelid early in its course. One growing on the outer (lateral) part of the wing may become quite large before causing symptoms, presenting as a painless swelling at the temple or a slowly progressive bulging of the eye as the thickened bone encroaches on the orbit. Surgical removal is challenging because the bone invasion often extends well beyond what imaging reveals, and complete resection sometimes requires removing portions of the orbital rim and reconstructing them.
An Evolutionary Footprint
The greater wing carries evolutionary information that anthropologists have used to trace relationships among human ancestors and their relatives. One useful feature is the position of the foramen ovale relative to the wing’s posterior border. In all living great ape species and in the early hominin Australopithecus afarensis, the suture line between the sphenoid and the temporal bone can split the foramen ovale, meaning the opening sits partly in one bone and partly in the other. In more recent human ancestors and in modern humans, the foramen ovale lies entirely within the greater wing of the sphenoid.19American Journal of Physical Anthropology. The posterior border of the sphenoid greater wing and its phylogenetic usefulness in human evolution
This seemingly minor difference reflects a broader reshaping of the skull base during hominin evolution. As the brain expanded and the face shortened, the greater wing expanded posteriorly, pulling the foramen ovale entirely within its territory. The shift is consistent enough to be useful in classifying fossil specimens: a skull in which the foramen ovale is split by the sphenosquamosal suture is more likely to belong to an earlier branch of the family tree.
The greater wing also has a deep evolutionary origin as a distinct bone. Comparative anatomists have traced it back to the epipterygoid, an element of the ancient jaw-support system in early vertebrates. The epipterygoid was part of the palatoquadrate cartilage, the same structure from which the mammalian upper jaw evolved, and it served as a structural bridge between the palate and the braincase.20Journal of Cleft Lip Palate and Craniofacial Anomalies. Pathologic anatomy of the soft palate, part 1: Embryology, the hard tissue platform, and evolution Over hundreds of millions of years, that strut was incorporated into the expanding sphenoid, becoming the broad wing we see today. Understanding this ancestry helps explain some otherwise puzzling features of the bone’s nerve and blood supply, which retain patterns inherited from its earlier role.
A History of Confusion
The sphenoid has a reputation as one of the hardest bones in the body to understand, and the greater wing has been part of that confusion for centuries. Because the sphenoid sits deep within the skull base, early anatomists could not access or visualize it without destroying the surrounding structures. For a long time, scholars disagreed about whether it was one bone or several, how many wings it had, and which sutures truly belonged to it. Its very name reflects this frustration: “sphenoid” comes from the Greek word for wedge, but as anatomists eventually conceded, the bone’s actual shape has little to do with a wedge.21PubMed Central. The “polymorphous” history of a polymorphous skull bone: the sphenoid
It was not until the eighteenth century that the sphenoid’s full configuration, including the distinction between greater and lesser wings, was worked out in a way that stuck. Modern imaging has largely resolved the old ambiguities, but the bone’s complexity continues to challenge students encountering it for the first time. The greater wing alone touches or articulates with at least six other skull bones, contributes to three different anatomical regions, and transmits half a dozen major neurovascular structures through its substance. For a single plate of bone, that is a remarkable amount of work.