SPHENOID BONE ANATOMY
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What is the sphenoid bone?
- Complex cranial bone located at skull base
- Functions as central wedge uniting cranial and facial skeletons
- Articulations:
- Vomer
- Ethmoid
- Frontal
- Occipital
- Parietal
- Temporal
- Zygomatic
- Palatine
Sphenoid Bone - Articulations, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
Structural Components
- Central body
- Two greater wings
- Two lesser wings
- Two pterygoid processes
BODY OF SPHENOID
Body of Sphenoid Bone, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
What is the body of the sphenoid?
- Hollow cuboid-shaped central portion
Superior Surface Features
What are the superior surface features of the sphenoid body?
What is the sphenoidal yoke?
- Sphenoidal Yoke — elevated midline region
- Site where lesser wings converge
What is the limbus of the sphenoid?
- Limbus of Sphenoid — posterior boundary of yoke
What is the chiasmatic sulcus?
- Chiasmatic Sulcus — horizontal groove
- Located posterior to limbus
- Accommodates optic chiasm
What is the sella turcica?
- Sella Turcica — saddle-shaped depression
- Houses pituitary gland
What is the hypophysial fossa?
- Hypophysial Fossa — deepest portion of sella turcica
What is the tuberculum sellae?
- Tuberculum Sellae — anterior boundary of sella turcica
What are the middle clinoid processes?
- Middle Clinoid Processes — flank tuberculum sellae bilaterally
What is the dorsum sellae?
- Dorsum Sellae — posterior wall of sella turcica
- Bears posterior clinoid processes superiorly
- Provides dural attachment sites
What is the carotid sulcus?
- Carotid Sulcus — broad lateral groove
- Lodges internal carotid artery
- Contains cavernous sinus
What is the sphenoidal lingula?
- Sphenoidal Lingula — bony ridge
- Marks lateral margin of carotid sulcus
Body of Sphenoid - Anterior Surface, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
Anterior Surface Features
What are the anterior surface features of the sphenoid body?
What is the sphenoidal crest?
- Sphenoidal Crest — vertical midline ridge
- Articulates with perpendicular plate of ethmoid
What is the sphenoidal rostrum?
- Sphenoidal Rostrum — inferior extension of crest
- Articulates with vomer
Sphenoidal Sinuses
What are the sphenoidal sinuses?
- Two irregular cavities within body
- Separated by thin bony septum
- Open into nasal cavity via apertures beside crest
What are the sphenoidal conchae?
- Sphenoidal Conchae — thin curved bony plates
- Form part of nasal cavity roof
- Contribute to sinus walls
LESSER WING
Lesser Wing of Sphenoid, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
What is the lesser wing of the sphenoid?
- Thin triangular plates extending laterally
- Project from superior anterior part of body
- Contributions:
- Floor of anterior cranial fossa
- Posterior part of orbital roof
What is the optic canal?
- Optic Canal — located at wing base
- Transmits optic nerve
- Transmits ophthalmic artery
What are the anterior clinoid processes?
- Anterior Clinoid Processes — arise from posterior border medially
- Serve as tentorium cerebelli attachment
- Tentorium separates cerebrum from cerebellum
GREATER WING
Greater Wing of Sphenoid, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
What is the greater wing of the sphenoid?
- Strong curved extensions from lateral body
- Contributions:
- Middle cranial fossa floor
- Lateral skull wall
- Orbital lateral wall
Foramina
What is the foramen rotundum?
- Foramen Rotundum — transmits maxillary nerve
What is the foramen ovale?
- Foramen Ovale — transmits mandibular nerve
- Also transmits accessory meningeal artery
What is the foramen spinosum?
- Foramen Spinosum — transmits middle meningeal artery
What is the sphenoidal emissary foramen?
- Sphenoidal Emissary Foramen — occasionally present
- Transmits emissary veins
What is the foramen petrosum?
- Foramen Petrosum — occasionally present
- Transmits lesser petrosal nerve
What is the spine of the sphenoid?
- Spine of Sphenoid — lateral to foramen spinosum
- Provides ligament attachment
What is the sulcus of the auditory tube?
- Sulcus of Auditory Tube — along posterior margin laterally
- Provides attachment for cartilaginous auditory tube
Greater Wing - Surfaces and Margins, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
Surfaces
What is the temporal surface of the greater wing?
- Lateral Surface — divided by infratemporal crest
- Temporal Surface — superior portion
- Forms part of temporal fossa
- Temporal Surface — superior portion
What is the infratemporal surface of the greater wing?
- Infratemporal Surface — inferior portion of lateral surface
- Forms part of infratemporal fossa
What is the orbital surface of the greater wing?
- Orbital Surface — smooth
- Forms lateral orbital wall
What is the cerebral surface of the greater wing?
- Cerebral Surface — superior aspect
- Forms middle cranial fossa floor
Margins and Articulations
What is the zygomatic margin of the greater wing?
- Zygomatic Margin — articulates with zygomatic bone
What is the frontal margin of the greater wing?
- Frontal Margin — articulates with frontal bone
What is the parietal margin of the greater wing?
- Parietal Margin — articulates with parietal bone
What is the squamosal margin of the greater wing?
- Squamosal Margin — articulates with temporal bone
PTERYGOID PROCESS
Pterygoid Process, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
What is the pterygoid process?
- Extend inferiorly from body-greater wing junction
- Plates fused anteriorly
What is the lateral pterygoid plate?
- Lateral Pterygoid Plate
- Lateral surface — lateral pterygoid muscle attachment
- Medial surface — medial pterygoid muscle attachment
What is the medial pterygoid plate?
- Medial Pterygoid Plate
- Contributes to nasal cavity
What is the pterygoid hamulus?
- Pterygoid Hamulus — hook-like inferior projection of medial pterygoid plate
- Acts as pulley for tensor veli palatini tendon
What is the pterygoid notch?
- Pterygoid Notch — separates plates inferiorly
What is the pterygoid fossa?
- Pterygoid Fossa — between medial and lateral plates
- Accommodates soft palate muscles
Pterygoid Process - Posterior View, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
Posterior Features
What is the scaphoid fossa?
- Scaphoid Fossa — superior to pterygoid fossa
- Tensor veli palatini attachment site
What is the pterygospinous process?
- Pterygospinous Process — pointed projection
- Located on posterior border of lateral plate
- May ossify to form ligament
What is the pterygoid canal?
- Pterygoid Canal — traverses process base
- Transmits nerve of pterygoid canal
- Transmits artery of pterygoid canal
VAGINAL PROCESS
Vaginal Process of Sphenoid, Preview from the app. Download 3D OSTEOLOGY for full 3D control—multiple views, x-ray mode, and unlimited zoom.
What is the vaginal process?
- Small bony projections flanking sphenoidal rostrum
- Articulations:
- Sphenoidal process of palatine bone
- Ala of vomer
Associated Canals
What is the palatovaginal canal?
- Palatovaginal Canal — formed with palatine bone
- Derived from palatovaginal groove
- Transmits pharyngeal nerve
- Transmits pharyngeal vessels
What is the vomerovaginal canal?
- Vomerovaginal Canal — formed with vomer
- Derived from vomerovaginal groove
BIBLIOGRAPHY
1. Henry G, Warren HL. Osteology. In: Anatomy of the Human Body. 20th ed. Philadelphia: Lea & Febiger; 1918. p. 129–97.