General Survey of the Skull

How many bones are in the skull?

14 facial

8 cranial

22 total

How are the cranial bones classified?

flat bones

How are the facial bones classified?

irregular bones

What is the function of the cranial bones?

protect the brain

What is the function of the facial bones?

provide structure and shape to the face

List the cranial bones (and whether they are paired or individual)

• frontal (1)

• parietal (2)

• occipital (1)

• temporal (2)

• sphenoid (1)

• ethmoid (1)

What is the most anterior cranial bone?

frontal bone

The frontal bone makes up the ___

forehead and superior orbits

The parietal bone makes up the ___

majority of the superior aspect of the cranium

What is the most posterior cranial bone?

occipital bone

Which bone contains the foramen magnum?

occipital

The temporal bone makes up the ___

area by the ear

Where does the sphenoid bone sit?

in the middle floor of the skull

The sphenoid bone forms the ___

orbits and posterior nasal cavity

The ethmoid bone lies within the ___

frontal bone

The ethmoid bone forms the ___

orbits and nasal cavity walls

Facial bones can also be called ___

visceral cranium

Explain the shape and location of the nasal bones

• 2 small oblong bones

• placed side by side at the middle and upper part of the face

Explain the location of the maxilla

2 bones that join at midline just above the teeth

The maxilla forms the ___

upper jaw

The maxilla houses the ___

upper teeth

The zygomatic bones form the ___

cheekbones

Explain the size and location of the lacrimal bones

• 2 of the smallest and most fragile bones of the face

• at the front part of the medial wall of the orbit (located between the maxilla and ethmoid)

Which bone contains our tear ducts?

lacrimal bones

Explain the location of the palatine bones

2 bones situated at the back part of the nasal cavity between the maxilla and sphenoid

The palatine bones form the ___

roof of the mouth and part of the orbit

Explain the shape, location, and function of the inferior nasal conchae

• 2 bones

• scroll-like appearance

• inferior, lateral aspect of nose

• cleans and filters air

Explain the location and function of the vomer

• single bone

• helps to form the nasal septum

• located in the MSP posterior to the palatine

What is the largest moveable facial bone?

mandible

What is the articulation between the mandible and temporal bone?

TMJ joint

diarthrodial, synovial, condylar

The mandible forms the ___

lower jaw

What makes up the calvaria?

• frontal

• occipital

• parietals

What is the most superior part of the skull called?

vertex

What makes up the skull floor?

• ethmoid

• sphenoid

• temporals

List the fossa of the cranial floor

1. anterior (frontal/ethmoid)

2. middle (sphenoid/temporal)

3. posterior (occipital/base of skull)

What are the measurements of the skull?

• 6 inches side to side

• 7 inches front to back

• 9 inches top to bottom (including mandible)

How are skull bones formed?

• intramembranous ossification

  • formed by a thin membranes made up of embryonic connective tissue arranged in sheets like layers

• flat bones have a 4 step process:

  • ossification center appears in fibrous connective tissue membrane

  • bone matrix is secreted

  • trabecula and periosteum form

  • formation of compact bone

Explain diploe

bones of the cranium are composed of 2 plates of compact bone separated by an inner layer of spongy tissue called diploe

What are the 4 sutures of the skull?

• coronal (between frontal and parietal)

• sagittal (between parietals)

• lambdoidal (between occipital and parietal)

• squamosal (between temporal and parietal)

Skull sutures are classified as ___

fibrous, synarthrodial

What are the functions of fontaneles?

• fetal skull can compress as it passes through birth canal

• rapid growth of the brain during infancy

Explain the anterior fontanele

• bregma

• where parietals and frontal bone meet

• at vertex

• closes at 18-24 months

Explain the posterior fontanele

• lambda

• where parietals and occipital bone meet

• closes at 2-6 months

Explain the sphenoid fontanele

• pterion

• parietal, sphenoid, and temporal bones

• closes at 3 months

Explain the mastoid fontanele

• asterion

• occipital, parietal, and temporal bones

• closes at 12 months

What is squamous?

the flat part of a bone

What is lateral/outer canthus?

where your eyelids unite laterally

What is medial/inner canthus?

where your eyelids unite medially

What is TEA?

Top of Ear Attachment (where top of ear attaches to skull)

What is EAM?

External Auditory Meatus (the ear hole)

What are radiographic baselines?

lines that start at the EAM and go anterior toward the face

What is the MML?

mentomeatal line

chin to EAM

What is the LML?

lips meatal line

lips to EAM

What is the AML?

acanthiomeatal line

point just under nose to EAM

What is the IOML?

infraorbitomeatal line

below eyes to EAM

What is the OML?

outer canthus to EAM

What is the GML?

glabellomeatal line

glabella to EAM