Unit III - Cranial Bone Markings

supraorbital notch or foramen: notch or small hole located along the superior margin of the orbit

frontal sinus: two large cavities located superior and medial to the orbits.

zygomatic process: anterior extension of bone, forms the posterior portion of the zygomatic arch

styloid process: projection from the inferior surface of the temporal bone

carotid canal: medial and anterior to styloid process

mandibular fossa: depression below the zygomatic process; where the mandible articulates

external acoustic (meatus) canal: opening along the external surface of the bone that is the passageway to the eardrum

internal acoustic (meatus) canal: opening along the internal surface of the bone for auditory nerves

mastoid process: large protrusion posterior and lateral to styloid process

stylomastoid foramen: small hole between mastoid process and styloid process

foramen magnum: large opening at the base of the skull

occipital condyles: prominent, rounded elevations located to the sides of the foramen magnum

hypoglossal canal: hole located in basilar part of bone superior to occipital condyle

jugular foramen: large, irregular opening along junction of occipital and temporal bone

external occipital protuberance: elevation on bottom center

greater wings: prominent wing-like lateral extension from the body of the sphenoid bone

lesser wings: small lateral extension from the body

sella turcica: depression that houses the pituitary gland

pterygoid processes (lateral and medial pterygoid plates)

optic canal: opening along junctions of lesser wing and body, passageway for optic nerve

superior orbital fissure: elongated, narrow opening that runs diagonally along the back of the orbit, between lesser and greater wings.

foramen ovale: oval hole in the greater wing (great landmark for locating other markings)

foramen spinosum

foramen lacerum

foramen rotundum

sphenoid sinus

perpendicular plate: thin vertical plate that extends down into nasal cavity

cribiform plate: horizontal plate in cranial floor and roof of nasal cavity that articulates with the frontal bone

crista galli: thin vertical plate that extends up from the cribiform plate

middle nasal conchae: thin plate that extends down in the nasal cavity, lateral to perpendicular plate

ethmoidal sinuses: a collection of small cavities located between the orbits in the lateral masses of the ethmoid bone.