Frontal, Parietal, Occipital, & Temporal Bones

The frontal bone forms the ___

forehead and part of the vertex (calvaria) of the skull

Metopic suture

where the 2 frontal bones meet (they fuse into 1 bone early in life)

What are the 3 parts of the frontal bone?

1. squamous part (forehead)

2. orbital part

3. nasal part

Frontal eminence

2 round prominences on the squamous part of the frontal bone (one on each side of the midline)

Supraorbital margins

ridges of bone that form the superior borders of the circular opening into each orbit

Supraciliary arches

above the supraorbital margin (the part covered by the eyebrows)

Supraorbital notch/foramen

groove or hole located toward the medial end of each supraorbital margin (transmits nerves to the face)

Nasion

landmark between the supraorbital margins

(top of the nose)

Glabella

landmark between the supraciliary arches

(bump between forehead and nose)

Frontal sinus

air filled asymmetric cavity in the frontal bone

What are the features of the squamous part of the frontal bone?

frontal eminence, supraorbital margin, supraciliary arches, supraorbital notches/foramen

Orbital plates

2 flat plates of bone that form the roof of each orbit

a part of the frontal bone

Ethmoidal notch

gap between the medial borders of the 2 orbital plates

What are the features of the orbital part of the frontal bone?

orbital plates and ethmoidal notch

Where is the nasal part of the frontal bone?

extends down the midline between supraorbital margins

Frontal nasal spine

a pointed process that extends down from the nasal part of the frontal bone

Parietal eminence

rounded prominences of the lateral surface of the parietal bones

What gives our skull its greatest transverse diameter?

parietal eminences

The ___ bone forms the base of the cranium

occipital

Foramen magnum

large opening in the inferior part of the occipital bone (where the medulla oblongata joins the spinal cord)

Squamous part of the occipital bone

external occipital protuberance OR inion

Lateral parts of the occipital bone

2 oval shaped regions located on the inferior surfaces of each side of the foramen magnum

Occipital condyles

oval shaped prominences located on the inferior surface (articulates with C1)

Condylar canals/fossa

fossae posterior to the occipital condyles

Hypoglossal canals

fossae anterior to the occipital condyles (passageway for the 12th cranial nerve)

Basilar part (of occipital bone)

part sloping up from occipital bone, anterior portion of foramen magnum (where basilar artery sits)

Clivus

sloping portion between sphenoid bone and basilar part of the occipital bone

The ___ bone contains the organs of hearing

temporal

What are the 3 parts of the temporal bone?

1. squamous part

2. petrous part

3. tympanic part

Mastoid process

contains the mastoid air cells and acts as a buffer in the inner ear in case the Eustachian tube malfunctions (large process)

Styloid process

thin process anterior and medial to the mastoid process

Squamous part of the temporal bone

flat part above the ear

Zygomatic process of the temporal bone

slender process that extends forward and meets the zygoma bone to form the zygomatic arch

Petrous part of the temporal bone

“petrous pyramid”

shaped like a pyramid/wedge and houses the parts of the ear that hear

What foramen are contained in the petrous part of the temporal bone?

• jugular

• carotid

• internal auditory meatus

• foramen lacerum

Explain the location and function of the jugular foramen

• opening in the suture between the occipital and petrous portion

• transmits internal jugular vein and cranial nerves 9, 10, and 11

What is the function of the carotid foramen?

transmits internal carotid artery

Explain the location and function of the foramen lacerum

• at the articulation of temporal, sphenoid, and occipital bones

• pharyngeal artery passes through

Explain the 3 skull shapes

• mesocephalic

  • 45-47^o from MSP

  • normal

• brachiocephalic

  • 54^o from MSP

  • short head - coronal craniostenosis

• dolichocephalic

  • 40^o from MSP

  • long head - sagittal craniostenosis

Explain the tympanic part of the temporal bone

forms the anterior and inferior walls of the EAM (also helps to form the mandibular fossa)

Explain the mandibular fossa (including joint classification)

• depression on temporal bone in front of EAM

• condyle of the mandible fits into this to form the TMJ

• condylar/ellipsoidal

What is shown in green?

orbital plates

What is shown in red?

parietal eminence

What is shown in red?

inion (external occipital protuberance)

What is shown in green?

occipital condyles

What canal/foramen is the rod going through?

hypoglossal canal

What is shown in red?

the basilar part of the occipital bone (potentially part of the clivus as well)

What is shown in green?

mastoid process

What is shown in green?

carotid canal

What is shown in green?

jugular foramen

What is shown in green?

foramen lacerum