Osteology of The Head and Neck

Question 1

What are the functions of the skull?

Answer 1

Protects the brain, brainstem, cranial nerves and vasculature
Provides attachment for muscles
Provides a framework for the head
Gives us our identity

Question 2

How are the different types of bones formed?

Answer 2

Flat - intramembranous ossification
Irregular - endochondral ossification

Question 3

What are pneumatised bones and what are their purpose?

Answer 3

Bones with air spaces (air cells or sinuses)
Reduces skull weight and adds resonance to the voice

Question 4

Give examples of pneumatised bones

Answer 4

Frontal
Temporal
Sphenoid
Ethmoid

Question 5

What does the neurocranium include?

Answer 5

Bony case of the brain, cranial meninges, with a dome-like roof - calvaria, and floor - cranial base

Question 6

What does the viscerocranium include?

Answer 6

Facial skeleton - anterior part of cranium consisting of bones surrounding the oral cavity, nasal cavity and most of the orbit

Question 7

What are the bones of the neurocranium?

Answer 7

Frontal
Parietal x2
Occipital
Sphenoid
Temporal x2
Ethmoid

Question 8

What are the bones of the viscerocranium?

Answer 8

Palatine x2
Lacrimal x2
Nasal x2
Zygomatic x2
Inferior Nasal Concha x2
Maxilla x2
Mandible
Vomer

Question 9

What are the different views of the skull

Answer 9

Lateral - Norma lateralis
Above - Norma verticalis
Below - Norma basalis
Behind - Norma occipitalis
In front - Norma frontalis

Question 10

What features of the skull can be seen laterally?

Answer 10

Neurocranium - external acoustic meatus, styloid and mastoid processes and temporal fossa
Viscerocranium - zygomatic arch, mandible and infratemporal fossa

Question 11

What are the borders of the temporal fossa?

Answer 11

Superior and posterior - superior and inferior temporal lines
Anterior - frontal process of zygomatic bone and zygomatic process of frontal bone
Inferior - infratemporal crest deep to zygomatic arch

Question 12

Give examples of landmarks in the neurocranium

Answer 12

Asterion
Inion
Lambda
Vertex
Bregma
Pterion
Glabella
Nasion

Question 13

What is the pterion?

Answer 13

H-shaped junction of sutures - frontal, parietal, temporal and greater wing of sphenoid bone
Structurally weak area of the skull and vulnerable to injury

Question 14

Why should pterion injury be taken seriously?

Answer 14

Overlies anterior branch of middle meningeal artery which if damaged can lead to extradural (epidural) hematoma

Question 15

How can the pterion be located?

Answer 15

4cm superior to midpoint of zygomatic arch
3cm posterior to frontal process of zygomatic bone

Question 16

What is the lambda?

Answer 16

The intersection of the sagittal and lambdoid suture

Question 17

What are Wormian bones and where are they found?

Answer 17

Small islands of bone that may be seen within a cranial suture
Most commonly seen in the lambdoid suture

Question 18

What are fontanelles?

Answer 18

Fibrous membranes that fuse in post natal life

Question 19

Name the different fontanelles?

Answer 19

Frontal
Parietal
Sphenoid
Mastoid

Question 20

Name the different paranasal sinuses

Answer 20

Frontal sinuses
Ethmoidal cells
Maxillary sinuses

Question 21

Give examples of landmarks found from the Norma basalis view of the skull

Answer 21

Carotid canal
Jugular foramen
Foramen magnum
Incisive fossa
Greater palatine foramen
Foramen lacerum
Foramen ovale
Foramen spinosum
Hypoglossal canal

Question 22

Where is the ligamentum nuchae found?

Answer 22

Attaches the external occipital protuberance and foramen magnum to the spinous processes of the cervical vertebrae

Question 23

What is the purpose of the ligamentum nuchae?

Answer 23

Supports the head and resists flexion
Attachment point for muscles

Question 24

Which cervical vertebrae are bifid?

Answer 24

C2 - C6

Question 25

What are the names of the atypical spinal vertebrae?

Answer 25

C1 - atlas C2 - axis C7 - vertebra prominens

Question 26

Name the features found in typical cervical vertebrae

Answer 26

Transverse process - foramen transversarium - posterior tubercle and anterior tubercle Body Spinous process Vertebral arch Vertebral foramen Lamina Articular facets

Question 27

Describe C7

Answer 27

Spinous process elongated but not bifid - site of attachment for the ligamentum nuchae Smaller foramen a transversaria as the vertebral artery does not need to pass through it

Question 28

Where does articulation occur?

Answer 28

At the articular facets where the superior facet articulates with the inferior facet of the preceding vertebra

Question 29

Describe C1

Answer 29

Has anterior and posterior arches No body Anterior arch has articular facet for the dens of C2 Has superior articular facet for occipital condyle Has transverse process and transverse foramina

Question 30

Describe C2

Answer 30

Has a body Has a bifid spinous process Has transverse process and transverse foramina Has dens or odontoid process which acts as an axis for the atlas and atlanto-occipital joint Has large superior articular facets

Question 31

Where is the atlanto-occipital joint found and what does it allow?

Answer 31

Between the skull and C1 Allows flexion and extension of the condyloid joint (nodding)

Question 32

Where is the lateral atlanto-axial joint and what does it allow?

Answer 32

Between C1 and C2 Allows rotation of head (side to side) Assisted by transverse ligament of atlas holding the dens in position

Question 33

What does the lateral atlanto-axial joint replace?

Answer 33

An intervertebral disc between C1 and C2

Question 34

What are alar ligaments?

Answer 34

Ligaments that prevent excessive rotation of the head and neck They connect the dens to the occipital condyles

Question 35

Describe the hyoid bone

Answer 35

U shaped bone found at C3 level of neck Does not articulate with any skeletal elements, suspended by muscles and ligaments Connects oral cavity with pharynx posteriorly and larynx inferiorly- helping to keep airway open Site of attachment for suprahyoid and infrahyoid muscles

Question 36

What are the purpose of the lesser horns of the hyoid bone?

Answer 36

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