Structure of the bone body (Corpus)
The body of the sphenoid bone resembles a cube. Inside it lie air-filled cavities — the sphenoidal sinuses (Sinus sphenoidalis). They are separated by the septum of sphenoidal sinuses (Septum sinuum sphenoidalium). On the anterior wall, these sinuses open via special apertures, next to which lie the sphenoidal conchae (Conchae sphenoidales).
Each surface of the body has its own anatomical features:
- Posterior surface fuses with the basilar part of the occipital bone. Initially, this junction is a synchondrosis (cartilaginous), which transforms into a synostosis (bony) with age.
- Lateral surfaces bear the carotid grooves (Sulcus caroticus), which are posteriorly bounded by the sphenoidal lingula (Lingula sphenoidalis).
- Anterior surface forms the sphenoidal crest (Crista sphenoidalis) along the midline. Inferiorly, it smoothly transitions into the sphenoidal rostrum (Rostrum sphenoidale).
- Superior surface faces the cranial cavity. In its center lies the famous sella turcica (Sella turcica), in the depression of which — the hypophysial fossa (Fossa hypophysialis) — the hypophysis (pituitary gland) rests. Anteriorly, the sella is bounded by the tuberculum sellae (Tuberculum sellae) with the middle clinoid processes, and posteriorly by the dorsum sellae (Dorsum sellae), from which the posterior clinoid processes extend. Anterior to the sella runs the prechiasmatic sulcus (Sulcus prechiasmaticus), followed by the jugum sphenoidale (Jugum sphenoidale).
Lesser wings (Alae minores)
The lesser wings project laterally from the body of the bone on both sides. Their superior surfaces face the cranial cavity (contributing to the formation of the anterior cranial fossa), while the inferior surfaces form the superior wall of the orbit — the orbital surface (Facies orbitalis).
Posteriorly and closer to the center, the lesser wings end in the anterior clinoid processes (Processus clinoidei anteriores). At the very base of each lesser wing runs the optic canal (Canalis opticus). The space remaining between the lesser and greater wings forms a crucial structure — the superior orbital fissure (Fissura orbitalis superior).
Greater wings (Alae majores)
The greater wings are characterized by a complex spatial organization. Each wing has five surfaces:
- Cerebral surface (Facies cerebralis) — faces the middle cranial fossa.
- Orbital surface (Facies orbitalis) — forms the lateral wall of the orbit.
- Temporal surface (Facies temporalis).
- Infratemporalis surface (Facies infratemporalis) — separated from the temporal surface by the infratemporal crest (Crista infratemporalis).
- Maxillary surface (Facies maxillaris) — forms the upper wall of the pterygopalatine fossa.
The wing articulates with adjacent bones via four margins: zygomatic, frontal, parietal, and squamous.
On the cerebral surface, just below the superior orbital fissure, lies a series of foramina:
- Foramen rotundum (Foramen rotundum). Next to it, an inconstant emissary sphenoidal foramen (Foramen venosum) is sometimes found.
- Slightly lateral and posterior lies the foramen ovale (Foramen ovale).
- Further laterally and posteriorly is the foramen spinosum (Foramen spinosum).
- As an anatomical variant, the foramen petrosum (Foramen petrosum) may be located between them.
On the infratemporal surface, the posterior border of the wing forms the spine of the sphenoid bone (Spina ossis sphenoidalis). The sulcus for the auditory tube (Sulcus tubae auditivae) runs along the same area.
Pterygoid process (Processus pterygoideus)
This paired process projects vertically downwards from the body of the bone. It is formed by two laminae fused anteriorly: the lateral lamina (Lamina lateralis) and the medial lamina (Lamina medialis).
The posterior margin of the lateral lamina bears the pterygospinous process (Processus pterygo spinosus). The medial lamina curves inferiorly, forming the pterygoid hamulus (Hamulus pterygoidei), on which the sulcus for the hamulus is noticeable.
Inferiorly between the laminae is the pterygoid notch (Incisura pterygoidea). On the assembled skull, the pyramidal process of the palatine bone tightly fits into this notch, and together they form the pterygoid fossa (Fossa pterygoidea). Superior to this fossa lies the scaphoid fossa (Fossa scaphoidea).
The vaginal process (Processus vaginalis) extends from the base of the medial lamina, participating in the formation of the palatovaginal and sphenovaginal grooves. The pterygoid canal (Canalis pterygoideus) passes straight through the base of the pterygoid process.
Briefly: answers to topical questions
What passes through the foramen rotundum of the sphenoid bone?
The maxillary nerve passes from the cranial cavity into the pterygopalatine fossa through the foramen rotundum of the sphenoid bone. This structure is the second branch of the trigeminal nerve and provides sensory innervation to the tissues of the upper jaw, nose, palate, and middle facial region.
What passes through the optic canal of the sphenoid bone?
The optic nerve, ophthalmic artery, and central retinal artery pass through the optic canal of the sphenoid bone. The ophthalmic artery passes through the optic canal alongside the optic nerve, lying lateral to it.
What passes through the foramen spinosum of the sphenoid bone?
The middle meningeal artery, vein, and a branch of the mandibular nerve pass through the foramen spinosum. The middle meningeal artery enters the cranial cavity via the foramen spinosum and supplies most of the dura mater.
What passes through the superior orbital fissure?
The ophthalmic nerve, as well as the oculomotor, trochlear, and abducens cranial nerves, pass from the cranial cavity into the orbit through the superior orbital fissure. The venous and vascular structures passing through it include the superior ophthalmic vein and sometimes anterior meningeal branches from the ophthalmic artery.
Which parts of the sphenoid bone participate in forming the orbital walls?
The following parts of the sphenoid bone participate in forming the orbital walls:
- Lesser wings (Alae minores) — the inferior surface forms the superior wall of the orbit.
- Greater wings (Alae majores) — the orbital surface forms the lateral wall of the orbit.
- Body (Corpus) — the lateral surface participates in forming the medial wall of the orbit.
What passes through the pterygoid canal?
The artery of the pterygoid canal and the nerve of the pterygoid canal pass through the pterygoid canal. The artery of the pterygoid canal is a branch of the maxillary artery, and the nerve of the pterygoid canal is formed by the union of the greater and deep petrosal nerves.
What passes through the foramen ovale of the sphenoid bone?
The mandibular nerve, which is the third mixed branch of the trigeminal nerve, exits the cranial cavity through the foramen ovale. Additionally, venous connections between the pterygoid plexus and the cavernous sinus pass through the region of the foramen ovale.
The foramina of the greater wing (from anterior to posterior) are easily remembered by the mnemonic: Rotundum, Ovale, Spinosum.
Class and exam questions
Which sinuses are located in the sphenoid bone?
Paired sphenoidal sinuses (Sinus sphenoidalis) are located within the body of the bone; they belong to the pneumatic pathways and are separated by a septum.
Where is the sella turcica located and what lies within it?
The sella turcica is located on the superior surface of the body of the sphenoid bone. In its center is the hypophysial fossa, which houses the pituitary gland.
What structures form the superior orbital fissure?
It represents a space bounded superiorly by the lesser wing and inferiorly by the greater wing of the sphenoid bone.
What else to study on this topic
- Boundaries and structures of the sella turcica: processes and sulci
- Variant anatomy of the greater wing foramina (venous and petrosal)
- Participation of the greater wing surfaces in forming the cranial fossae
- Mechanism of formation of the pterygoid fossa together with the palatine bone
- Grooves of the vaginal process: palatovaginal and vomerovaginal
Study the complete topic in the Anatomy course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on the topic "Sphenoid bone" and another 1,363 pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 295 video lessons by subject
Other topics in the "Skull" section
Free video lessons: AnatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.