Resources (quick overview)
Unpaired bone of skull, that contributes to both the neuro and viscerocranium:
Cranial Vault: Floor of the anterior middle cranial fossa + Posterior Boundary of the anterior cranial fossa.
Lateral Skull: contributes to pterion.
Skull base: contributes to infratemporal fossa.
- Contributes to Medial Wall of Orbit + Roof of Nose.
- the lesser wing
- the greater wing
- the body
- the pterygoid process - (this is the part that most people forget)
Cranial Vault Surfaces:
Posterior Surface - basiocciput + petrous temporal bones.
Laterally squamous temporal bone.
-anterior- frontal bone of anterior cranial fossa.
- hollowed centrally as the sphenoidal air sinuses
- superior surface is the sella turcia for the pituitary.
- anterior surface: sphenoidal crest - articulates with perpendicular plate of ethmoid.
- Inferior surface: sphenoidal rostrum - continuation of crest - articulates with vomer.
cavernous sinus laterally and laterally grooved by internal carotid artery.
Anteriorsuperiorly grooved by chiasmatic chasm.
Tuberculum Sella anteriorly.
Dorsum Selle posteriorly.
Anterior Clinoid Process - from medial part of lesser wing (but most anterior process) attachment for tentorium cerebelli.
Middle Clinoid Process - from tuberculum sellae
Posterior Clinoid Process - from dorsum sellae. - attachment for tentorium cerebelli.
The diagrama sellae is attached to the anterior and posterior clinoid processes and provides a roof for pituitary fossa.
Superior Oblique Muscle arises from the body of the sphenoid.
interclinoid and carotoclinoid ligaments.
Lesser Wing of Sphenoid
Posterior boundary of anterior Cranial Fossa
Medial end is projected back as the anterior process of the clinoid.
Base perforated by the optic canal.
Jugum: the space joining both lesser wings together.
Levator Palpebrae superioris arises from the lesser wing (at the apex of the roof)
Sphenoparietal Sinus - temporal region of the vault - edge of lesser wing of sphenoid.
Greater Wing of Sphenoid
Forms part of infratemporal fossa (with squamous part of temporal bone).
Upper head lateral pterygoid arises from infratemporal surface.
Anterior boundary is inferior orbital fissure behind maxilla.
Medial boundary - 45 degree edge with apex petrous temporal bone.
Posterior boundary - posterior end of 45 degree edge of petrous temporal bone demarcated by sphenoid spine.
Lateral boundary infratemporal crest - bone then contributes to temporal fossa. .
grooved by chorda tympani on medial spine.
sphenomandibular ligament - attaches to inferior margin of mandibular foreamen. (considered accessory ligament of temporomandibular joint.
Anterior Ligament - (from anterior process of malleus) passes through the squamotympanic fissure to the spine of the sphenoid.
Posteriomedial is the isthmus of the auditory tube. Cartilaginous part groes through groove between greater wing of sphenoid and apex petrous temporal bone.
Greater Wing Foramen
venous foramen of versalius - communicating vein pterygoid and cavernous sinus
Less commonly petrosal foreamen.
Infratemporal Crest is where temporal fossa becomes continuous with infratemporal fossa.
- common origin of extension for pterygoid plates
- descends from junction of body of sphenoid and greater wing.
- The posterior wall of the pterygopalatine Fossa.
Media pterygoid plate
1. posterior boundary nose.
2. tip (spur): pharyngobasillar fascia - superior pharyngeal constrictor are attached.
Pterygoid hamulus - u shaped lateral projection of the medial pterygoid plate:
1. fibrous band attaches - pterygomaxillary ligament (to tuberosity of the maxilla) - (bucinnator origin).
2. Pterygomaxillary ligament converts hamulus into fibroosseous canal for tensor veli palatini.
3. Pterygomandibular Raphe
Pterygoid tubercle - end of medial pterygoid plate the extends back into foreamen lacerum.
Scaphoid fossa - its the depression on the base of skull lateral to the pterygoid tubercle - from which the medial pterygoid plate arises. Tensor palati origin.
1. medial projection of the medial plate that ensheaths the body of the sphenoid and articulates with vomer.
2. The suture opens posteriorly as the vomerovaginal canal - pharyngeal branch of sphenopalatine artery.
3. Palatovaginal Canal - the more lateral canal of the two (vomerovaginal canal is medial) - pharyngeal branch of pterygopalatine "runs back hrough the canal ?recurrent?" supplies roof of nose + pharyngeal branch from 3rd part maxillary artery.
Pterygoid Canal in foramen lacerum - to pterygopalatine fossa - same line as medial pterygoid plate perforates the root of the pterygoid process. Almost same size as foreamen rotundum. Its aperture is between the lingula and pterygoid tubercle.
Pterygoid Notch - common lower border of the pterygoids, filled by triangular extremity of pyramidal process.
Lateral Pterygoid Plate attached to base of skull at anterior edge of foreamen ovale.
Lateral Surface is attachment for lower head of lateral pterygoid muscle.
Medial Surface is attachment for UPPER head of MEDIAL pterygoid muscle (both lower and lateral opposites).
Lateral Surface of the Lateral Plate is the attachment for the Lower head of the Lateral pterygoid.
Develops as presphenoid and postsphenoid (sella turcica is the divider)
Undergoes cartilaginous ossification.