Osteology of Skull, Hyoid & Cervical Spine

Question 1

how are bones of the skull joined

Answer 1

by fibrous joints called sutures

Question 2

where is movement in the cranial skull

Answer 2

only at the temporomandibular joint and the atlanto-occipital joint

Question 3

2 types of bones forming the skull

Answer 3

1. flat & irregular bones
2. pneumatised bones

Question 4

flat & irregular bones

Answer 4

formed by intramembranous ossification & endochondral ossification respectively

Question 5

pneumatised bones

Answer 5

bones with air cells / sinuses to reduce weight in the skull & add resonance to the voice

Question 6

examples of pneumatised bones

Answer 6

frontal, temporal, sphenoid and ethmoid bones

Question 7

2 divisions of the skull

Answer 7

1. neurocranium
2. viscerocranium (facial skeleton)

Question 8

neurocranium bones (8)

Answer 8

frontal
2x parietal
occipital
sphenoid
2x temporal
ethmoid

Question 9

viscerocranium bones (14)

Answer 9

2x palatine
2x lacrimal
2x nasal
2x zygomatic
vomer
2x inferior nasal concha
2x maxilla
mandible

Question 10

main features of viscerocranium

Answer 10

zygomatic arch, mandible & infratemporal fossa

Question 11

zygomatic arch

Answer 11

formed via the temporal process of the zygomatic bone and the zygomatic process of the temporal bone

Question 12

infratemporal fossa

Answer 12

found deep to zygomatic arch, communicates to he temporal fossa superiorly, contains muscular & neurovascular structures

Question 13

main features of neurocranium

Answer 13

external acoustic meatus, styloid & mastoid processes, temporal fossa

Question 14

borders of the temporal fossa

Answer 14

superior border - superior temporal line
posterior border - inferior temporal line
anterior border - frontal process of zygomatic bone & zygomatic process of frontal bone
inferior border - infratemporal crest, deep to zygomatic arch
floor - pterion

Question 15

vertex

Answer 15

most superior point of the neurocranium

Question 16

bregma

Answer 16

junction of the coronal and sagittal sutures

Question 17

lambda

Answer 17

where the lambdoid and sagittal sutures join

Question 18

inion

Answer 18

most prominent point of the external occipital protuberance

Question 19

asterion

Answer 19

a star shaped junction of 3 sutures between the occipital, parietal and temporal bones

Question 20

pterion

Answer 20

H shaped junction of sutures (frontal, parietal, temporal and greater wing of sphenoid) that overlies the anterior branch of the middle meningeal artery

Question 21

anterior fontanelle

Answer 21

diamond shaped, at site of bregma, fuses at around 18 months

Question 22

posterior fontanelle

Answer 22

triangular in shape, at site of future lambda, fuses before the first year

Question 23

what is the piriform arperture

Answer 23

this is the anterior nasal opening in the cranium

Question 24

what passes through supraorbital foramen

Answer 24

CN V1 the ophthalmic branch of trigeminal nerve

Question 25

what passes through the infraorbital foramen

Answer 25

CN V2 the maxillary branch of the trigeminal

Question 26

where does CN V2 exit interiorly in the skull

Answer 26

foramen rotundum

Question 27

what passes through the mental foramen

Answer 27

CN V3 the mandibular division of the trigeminal nerve

Question 28

how does CN V3 exit the cranium

Answer 28

through the foramen spinosum

Question 29

function of the vomer

Answer 29

contributes to the bony part of the nasal septum which separates the anterior nasal apertures & posterior nasal apertures (choanae)

Question 30

what canals are in the temporal bone

Answer 30

- carotid canal for internal carotid artery - jugular foramen for internal jugular vein (just posterior to the carotid canal)

Question 31

what opening is present in the occipital bone

Answer 31

foramen magnum for spinal cord, meninges, vertebral & spinal arteries, spinal root of accessory nerve CN XI

Question 32

what travels through the foramen spinosum other than CNV3

Answer 32

middle meningeal artery & vein

Question 33

purpose of ligamentum nuchae

Answer 33

to attach external occipital protuberance & foramen magnum to spinal processes of the cervical vertebrae (continuous with supraspinous ligament)

Question 34

function of ligamentum nuchae

Answer 34

to support head & resist flexion as well as an attachment point for some muscles

Question 35

what is present in cervical vertebrae only compared to other vertebrae

Answer 35

presence of foramina transversaria

Question 36

how does articulation occur in the cervical vertebrae

Answer 36

via articular facets with the superior facet articulating with the inferior facet of the preceding vertebrae

Question 37

site of attachment of ligamentum nuchae

Answer 37

spinous process

Question 38

when is the spinous process bifid / not bifid

Answer 38

bifid C2-C6 non bifid C7

Question 39

other names of C1 and C2

Answer 39

C1 = atlas C2 = axis

Question 40

main feature of C2

Answer 40

dens / odontoid process

Question 41

function of odontoid process

Answer 41

acts as an axis for the atlas and atlanto-occipital joint

Question 42

what does C1 have instead of a body

Answer 42

an anterior arch with an articular facet for the dens of C2

Question 43

what is missing at the atlanto-axial joint

Answer 43

between C1 and C2 there is no intervertebral disc

Question 44

function of atlanto-occipital joint

Answer 44

allows flexion & extension (nodding)

Question 45

function of lateral atlanto-axial joint

Answer 45

allows rotation of head from side to side

Question 46

where is the hyoid bone found

Answer 46

C3 level in anterior neck

Question 47

why is the hyoid bone unique

Answer 47

does not articulate with any skeletal elements in heck & neck and can be palpated

Question 48

what keeps the hyoid bone in place

Answer 48

muscles and ligaments with connections to mandible, styloid process, thyroid cartilage, manubrium & scapulae

Question 49

purpose of hyoid bone

Answer 49

connects oral cavity with the pharynx posteriorly, the larynx inferiorly and helps to keep the airway open

Question 50

lesser horn of hyoid purpose

Answer 50

forms site of attachment for stylohyoid ligament which connects the hyoid to the styloid process of the skull