Cranial Bones

Cranial Bones

1. Frontal

   • supraorbital margin "ridge" - ridge on top of eye socket. Can break blood vessels here forming black eye
   • Supraorbital foramen - small hole on ridge for nerves and blood vessels
   • Orbital surface - forms top of eye socket
   • frontal sinuses - cavities of air cells in bone. Located in bridge of nose by forehead and eyebrows.

2. Parietal

   • Superior temporal line
   • inferior temporal line

3. Temporal

   • zygomatic process - forms half of cheek bone and joins with temporal process on zygomatic bone
   • mastoid process - bump behind your ear. Sternocleidomastoid attachment point. Has air cells (sinus) that connect with middle ear.
   • styloid process - very pointy downwards. Attachment point for many ligaments and muscles.
   • external acoustic meatus - large hole that opens to external ear canal and ends at ear drum.
   • Internal acoustic meatus - visible in sagittal view. Where nerve for balance exits
   • Mandibular fossa - jaw joint under zygomatic process.
   • Stylomastoid foramen - Facial nerve CN 7 near mastoid and styloid process.
   • Jugular Fossa (foramen) - jugular vessel passing. Forms Jugular foramen when joined with occipital bone.
   • carotid canal - anterior to jugular fossa. Where INTERNAL carotid artery enters brain.
   • Petrous portion - houses inner ear structures for hearing and balance. Vestibular cochlear nerve CN 8 passes.

4. Occipital

   • Foramen magnum - large hole that connects spinal cord and brain stem
   • occipital condyle - articulates with 1st cervical vertebrae. Helps to nod head
   • External occipital protuberance - bump on the back of your head. Ligament attaches here to 7th cervical vertebrae to hold head upright.
   • Nuchal lines - trapezius muscle attachment
   • Hypoglossal canal - under the occipital condyle. Allows passage of CN 12 to control tongue.

5. Sphenoid

   • sphenoidal sinus
   • superior orbital fissure - hole lateral to sphenoidal sinus. Allows passage for 3 ocular CN nerves.
   • optic canal - CN2
   • cella tursica - saddle for brain on interior surface of bone
   • foramen rotundum - listed anterior to posterior
   • foramen ovale
   • foramen spinosum
   • Greater/lesser wings

6. Ethmoid

   • Christa Galli - forms nasal cavity and orbit of eye. Connects to "seat belt" of brain.
   • foramina - lots of foramen in cribiform plate. Olfactory nerves CN1 and ocular CN2 pass.
   • lateral masses - contains ethnoid sinuses (side of your nose)
   • nasal concha - forms turbulentia that create turbulence in air to help mucus trap dust ect.
   • perpendicular plate - nasal septum (divide bone into 2 cavities).

7. Sutures

   • Lambdoid: occipital and parietal bones. Sutural bones grow in gap.
   • Coronal - parietal and frontal bone
   • sagittal - parietal bone suture
   • Sqamous - parietal and temporal bone