Ch. 7 Axial Skeleton: Cranial Bones

Question 1

What does the axial skeleton include? How many bones total? Functions?

Answer 1

Skull, hyoid, vertebral column, thoracic cage
80 bones
Fxn: support head, neck, trunk; protect brain, spinal cord, thoracic organs

Question 2

Define foramen (foramina)

Answer 2

A hole in a bone (typically for nerves or blood vessels)

ex: foramen magnum, infraorbital inforamen

Question 3

Define fossa (fossae)

Answer 3

Depression in a bone

ex: mandibular fossa, lacrimal fossa

Question 4

Define process

Answer 4

Projection from bone, narrow or wide, protrudes from surrounding bone
ex: styloid or mastoid process

Question 5

Define meatus

Answer 5

Hole or tube-like structure

ex: auditory meatus

Question 6

Define canal

Answer 6

Groove or tube-like structure

ex: optic canal

Question 7

How many bones are in the skull? What type of bones?

Answer 7

28 bones

“Flat” bones (formed via intramembranous ossification)

Question 8

What are the 2 subdivisions of the skull?

Answer 8

Cranial and Facial

Question 9

Cranial bone functions (2)?

Answer 9

protect brain

provide attachment sites for some head/neck muscles

Question 10

Facial bone functions (4)?

Answer 10

form framework of face
openings for passage of air and food
hold teeth
anchor muscles of face

Question 11

In general, what are sutures?

Answer 11

interlocking, immovable joints that unite the bones of the skull

Question 12

Specifically, what are the 4 sutures of the skull? Where are they each located?

Answer 12

1. Coronal suture
   - -articulation between frontal and parietals
2. Squamous suture
   - -articulation between temporal and parietals
3. Lambdoid suture
   - -articulation between occipital and parietals
4. Saggital suture
   - -articulation between L and R parietals

Question 13

Skull terminology: What are the vault and base?

Answer 13

Vault: superior, lateral, and posterior bones of the skull (includes forehead)
–aka calvarium
Base: inferior part of cranium

Question 14

Name the 8 bones that make up the cranium

Answer 14

Frontal
Occipital
Sphenoid
Ethmoid
2 Parietals (L and R)
2 Temporals (L and R)

Question 15

Frontal Bone

Answer 15

forehead

The smooth medial part of the frontal bone between the superciliary arches is the glabella (in between your eyebrows)

Question 16

Parietal Bones

Answer 16

Paired (L and R)

Makes up most of the superior part of skull, extends posteriorly and laterally

Note saggital and lambdoid sutures

Question 17

Temporal Bones

Answer 17

Paired (L and R)
House opening to ear, base of cheekbone
3 main regions: petrous, tympanic, and squamous
Petrous is best seen internally, contains middle and inner ear cavities
External Acoustic Meatus (EAM): opening in tympanic region leading to middle and inner ear

Note mastoid process and styloid process

Question 18

Occipital Bone

Answer 18

Posterior to Cranium and cranial base

Foramen magnum: large opening in occipital bone that allows spinal cord to pass and connect w/ brain
–occipital condyles are region where skull articulates w/ vertebral column

Question 19

Temporomandibular Joint (jaw joint…TMJ)

Answer 19

Condylar process of lower jaw fits into depression in temporal bone (mandibular fossa)

Creates the TMJ

Question 20

Middle Ear Cavity (inside temporal cavity)

Answer 20

3 ear ossicles in middle ear: malleus, incus, and stapes (listed lateral to medial)

Malleus=hammer, Incus=anvil, Stapes=stirrup

Sound waves cause vibrations that are transmitted to inner ear

Question 21

Sphenoid

Answer 21

Large and wing-shaped (“gothic butterfly”)

Sella Turcica: bony depression that holds the pituitary gland

Sphenoid is the only cranial bone that articulates w/ every other cranial bone

Question 22

Ethmoid Bone and Nasal Cavity

Answer 22

Anterior to sphenoid is ethmoid
Ethmoid takes up most area between nasal cavity and orbits
Forms boundaries of nasal cavity, also separates nasal cavity from brain

Question 23

Ethmoid: Cribriform Plate and Crista Galli

Answer 23

Cribriform plate: helps form roof of nasal cavities; foramina allow passage of olfactory nerves to brain
–located superiorly

Crista Galli: attaches to cribriform plate; separates nasal cavity from brain, site of attachment for dura mater (brain membrane)
–located anteriorly

Question 24

Nasal Cavity in Saggital Section

Answer 24

Lateral walls of nasal cavity make up nasal bones, nasal conchae (supper, middle, inferior), frontal process of maxillae, perpendicular plate of palatines

Floor of nasal cavity: hard palate. Formed by palatine process of maxillae, horizontal plate of palatine.

Question 25

Paranasal Sinuses/Paranasal Cavity

Answer 25

Sinuses are found in the frontal bone, maxillary bone, ethmoid, and sphenoid