Skull

Question 1

What can the neurocranium be divided into?

Answer 1

Calvaria and cranial base

Question 2

What bones make up the anterior skull view?

Answer 2

-frontal (forehead)
-nasal (R/L on top of nasal cavity)
-maxilla (involved in eye socket, nasal cavity, and oral cavity/roof of mouth)
-zygomatic (part of eye socket and zygomatic arch/cheek bone)
-mandible (jaw)

Question 3

What are the landmarks of the frontal bone?

Answer 3

-supraorbital foramen (hole above eye socket that allows nerve to pass sensory info to forehead/top of head)

-nasion (junction between R/L nasal bones and frontal bone)

-glabella (smooth surface above the nasion)

Question 4

What is the landmark of the maxilla?

Answer 4

-infraorbital foramen (hole below eye socket that allows a nerve to spread sensory info to maxillary/mid region of the face)

Question 5

What are the landmarks of the mandible?

Answer 5

-mental foramen (hole on mandible which allows a nerve to spread sensory info to the jaw)

-mental protruberance (bony prominence in front of lower jaw, chin)

Question 6

What bones make up the lateral skull view?

Answer 6

-frontal-parietal-occipital-sphenoid (keystone of the skull)-temporal
: zygomatic arch (temporal and zygomatic bone form this)
: external acoustic meatus (opening to ear)
: mastoid process (bump on bottom of temporal)
: styloid process
-zygomatic
:zygomatic arch

Question 7

What is the temporal fossa?

Answer 7

Landmark of lateral skull: depression/hollow located above zygomatic arch

Question 8

What is the pterion?

Answer 8

Landmark of lateral skull: meeting/junction of the temporal, frontal, parietal and sphenoid

Question 9

What is the squamous suture?

Answer 9

Landmark of lateral skull: meeting/junction between the temporal and parietal bones

Question 10

What is the coronal suture?

Answer 10

Landmark of lateral skull: meeting/junction between frontal and parietal bones

Question 11

What is the lambdoid suture?

Answer 11

Landmark of lateral and superior skull: meeting/junction between the occipital and parietal bones

Question 12

What bones make up the superior skull view?

Answer 12

-parietal bones
-frontal bone
-occipital bone

Question 13

What is the sagittal suture?

Answer 13

Landmark of the superior skull: meeting/junction between the right and left parietal bones

Question 14

What is the coronal suture?

Answer 14

Landmark of superior skull: meeting/junction between the frontal and parietal bones

Question 15

What is the bregma?

Answer 15

Landmark of superior skull: meeting/junction of the coronal and sagittal sutures

Question 16

What is the lambda?

Answer 16

Landmark of superior skull: meeting/junction of the sagittal and lambdoid sutures

Question 17

What bones make up the inferior view (cranial base) of the skull?

Answer 17

-occipital
-temporal
-sphenoid (keystone of the skull)
-maxilla (hard palate-more anterior)
-palatine (hard palate-more posterior)

Question 18

What are the landmarks of the occipital bone?

Answer 18

-foramen magnum (large hole where spinal cord/brainstem pass through)

-EOP (external occipital protruberance), (bump on posterior base of skull)

Question 19

What are the landmarks of the temporal bone?

Answer 19

-mastoid process
-styloid process
-external acoustic meatus

-stylomastoid foramen (opening between styloid process and mastoid process to allow cranial nerve 7 to pass to the face)

-jugular fossa/foramen (opening at junction between occipital and temporal bones for IJV/CN: 9,10,11)

-carotid canal (opening anterior to jugular fossa for ICA to supply blood supply to the brain)

Question 20

What is the clinical application associated with the pterion (meeting point of the frontal, parietal, temporal, and sphenoid bones)?

Answer 20

The middle meningeal artery lies deep (beneath) the pterion

Because the pterion is the thinnest region of the skull, it is susceptible to fracture and trauma (which may lead to epidural hematoma-bleeding/damage to the middle meningeal artery)

Question 21

What bones make up the internal view (cranial base) of the skull?

Answer 21

-anterior fossa
-middle fossa
-posterior fossa

ridges will divide the fossa in the cranial base

Question 22

What are the landmarks of the anterior fossa?

Answer 22

-lesser wing of the sphenoid bone: surface of the “ridge” between anterior and middle fossa

-cribrifrorm plate of ethmoid bone: roof of the nose or nasal cavity, contains a bunch of small openings for CN1 to pass through/dangle at the top roof of the nose to transmit smell)

Question 23

What are the landmarks of the middle fossa?

Answer 23

-greater wing of sphenoid: the sides of the “ridge” between the anterior and middle fossa

-optic canal: opening (can be found by following the lesser wing of sphenoid bone medially) which allows for CN2 (optic nerve) to pass from the brain to the eyeball/retina

-sella turcica: center of the cranial base “saddle” which holds/protects the pituitary gland

-foramen lacerum: opening filled with cartilage that acts as a floor/seal which allows CCA to run through and connect to the circle of willis

-superior orbital fissure: opening just below the lesser wing which allows CN 3,4,6 and V1 of CN5 to pass through to the eye socket (extraocular muscles), V1 of C5 will travel to the forehead using the eye socket as a pathway

-foramen rotundum: first opening posterior to the superior orbital fissure, opening for V2 of CN5 to make its way toward the maxilla/mid face

-foramen ovale: oval shaped opening for V3 of CN5 to make its way to the mandible

-foramen spinosum: small opening behind the foramen ovale which allows the middle meningeal artery to pass through

Question 24

What are the landmarks of the posterior fossa?

Answer 24

-internal acoustic meatus: located in temporal bone ridge which contains CN7 (passing through to the face) and CN8 (supplies inner ear)

-jugular foramen: opening at the junction between temporal bone and occipital bone “kidney shaped”, allows for passage of IJV/ CN9, CN10, CN11

-hypoglossal canal: on occiptal bone, horizontal oriented opening that allows for CN12 to pass through the neck into the floor of the mouth

-foramen magnum: large opening in center of skull for spine/brainstem to pass through

Question 25

What is the purpose of skull radiography?

Answer 25

Rarely used in trauma unless a CT is unavailable, but can be used to identify bone pathology or presence of metal (metallic foreign bodies) before an MRI

Question 26

What would you look for in the cortex of the skull on a lateral x-ray?

Answer 26

-overall outline of the skull looking for consistency of contour (no lumps or bumps)

-consistent bone density throughout (dense outer bone and more spongey/light inner bone/trabeculae)

Question 27

What would you look for in the sella turcica on a lateral x-ray?

Answer 27

Normal contour and no expansion in size (pituitary tumor can push the bone apart/expand)

Question 28

What other landmark other than the sella turcica and cortex can be pictured by a lateral x-ray?

Answer 28

Sinuses (frontal and maxillary)