Chapter 11: Cranium, Facial Bones, and Paranasal Sinuses

How many bones are in the skull?

22

How many cranial bones?

8

How many facial bones?

14

Cranial bones are further divided into…

Calvaria and Floor

Calvaria

skull cap

Calvaria Bones

• Frontal

• Occipital

• Right Parietal

• Left Parietal

Floor Bones

• Ethmoid

• Sphenoid

• Right Temporal

• Left Temporal

How is the cranial floor divided?

There is the anterior cranial fossa, middle cranial fossa, and posterior cranial fossa.

Anterior cranial fossa

houses the frontal lobes of the cerebrum; extends from anterior frontal bone to lesser wings of sphenoid

Middle Cranial Fossa

houses temporal lobes; extends from lesser wings of sphenoid to apices of petrous ridges

Posterior Cranial Fossa

deep depression posterior to petrous ridges; protects cerebellum, pons, and medulla oblongata

Sutures

Fibrous joints that connect the bones of the skull

Cranial Sutures

• Coronal

• Lambdoidal

• Squamosal

• Sagittal

Junctions

• Asterion

• Bregma

• Lambda

• Pterion

Coronal Suture

Between frontal and parietal bones

Sagittal Suture

On top of head between two parietal bones

Squamosal

between temporal bones and parietal bones

Lambdoidal Suture

between occipital and parietal bones

Bregma

junction of coronal and sagittal sutures

Lambda

junction of sagittal and lambdoidal sutures

Pterion

junction of the parietal bone, squamosal suture, and greater wing of sphenoid

Asterion

junction of the occipital bone, parietal bone, and mastoid portion of the temporal bone

Fontanels

Areas of incomplete ossification in infant skulls

Mesocephalic

average shape of skull

Brachycephalic

Wider and shorter

Dolichocephalic

Narrower and longer

What are the 5 common positioning errors

1. Rotation

2. Tilt

3. Excessive Neck Flexion

4. Excessive Neck Extension

5. Incorrect CR Angle

Frontal Bones Landmarks

• Frontal Eminences

• Supraorbital Margins

• Supraciliary Arches

• Supraorbital Foramina

• Glabella