Osteology of skull, hyoid & cervical spine

Question 1

what is the most complex bony structure in the body?

Answer 1

The skull
- made up of 23 separate bones

Question 2

what are the functions of the skull?

Answer 2

• houses & protects the brain, brain stem, cranial nerves & vasculature
• protects the 5 organs of special sense
• provides attatchment for muscles
• provides framework for the head

Question 3

what are the 5 special senses?

Answer 3

• olfaction (smell)
• vision
• taste
• vestibular function
• auditory function

Question 4

what is the atlanto-occipital joint?

Answer 4

joint at base of skull & cervical spine

Question 5

what type of bones is the skull composed of?

Answer 5

• flat bones
• irregular bones
• pneumatised bones

Question 6

what is the difference between flat and irregular bones?

Answer 6

FLAT BONES
- formed by intramembranous ossification

IRREGULAR BONES
- formed by endochondral ossification

Question 7

what are pneumatised bones?

Answer 7

bones with air spaces (air cells or sinuses)

Question 8

what are examples of pneumatised bones?

Answer 8

• frontal bone
• temporal bone
• sphenoid bone
• ethmoid bone

Question 9

what are the functions of pneumatised bones in the skull?

Answer 9

• reduce weight of skull
• add resonance to our voice

Question 10

what are the developmental divisions of the skull?

Answer 10

Neurocranium
- portion of skull that protects the brain & organs of special sense
Viscerocranium
- facial skeleton (relating to the digestive & respiratory systems)

Question 11

what is the Norma Frontalis?

Answer 11

the anterior view of the skull

Question 12

what is the Norma Lateralis?

Answer 12

the lateral (side) view of the skull

Question 13

what is the Norma Occipitalis?

Answer 13

the posterior view of the skull

Question 14

what is the Norma Basalis?

Answer 14

the inferior view of the skull

Question 15

what is the Norma Verticalis?

Answer 15

the superior view of the skull

Question 16

What bones make up the Neurocranium?

Answer 16

• Frontal
• Parietal x2
• Occipital
• Sphenoid
• Temporal x2
• Ethmoid

Question 17

what bones make up the Viscerocranium?

Answer 17

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

Question 18

what is the zygomatic arch?

Answer 18

arch formed between the temporal process of the zygomatic bone and the zygomatic process of the temporal bone

Question 19

what is the external acoustic meatus?

Answer 19

the ear canal!

Question 20

What is the temporal fossa?

Answer 20

an area on the side of the cranium from which the temporal muscle arises

Question 21

What are the anterior borders of the temporal fossa?

Answer 21

• frontal process of zygomatic bone
• zygomatic process of frontal bone

Question 22

what is the inferior border of the temporal fossa?

Answer 22

• infratemporal crest deep to zygomatic arch

Question 23

What is the Vertex?

Answer 23

superior point of the neurocranium and is centred in the middle

Answer 24

junction of the sagittal & coronal suture (where they meet)

Question 25

what is the Lambda?

Answer 25

junction of the lambdoid and sagittal sutures

Question 26

what is the Inion?

Answer 26

most prominent point of the external occipital protuberance

Question 27

what is the Asterion?

Answer 27

star shaped junction between the occipital, parietal and temporal bones

Question 28

What is the nasion?

Answer 28

where the frontonasal and internasal sutures meet

Question 29

what is the Glabella?

Answer 29

- a smooth part of frontal bone superior to the root of the nose - the most anterior projecting part of the forehead

Question 30

What is the Pterion?

Answer 30

- H-shaped junction of sutures (where the frontal, parietal, temporal & greater wing of sphenoid meet)

Question 31

What is interesting about the Pterion?

Answer 31

structurally weak point of the skull

Question 32

Why is an injury to the pterion clinically relevant?

Answer 32

- vulnerable to injury as structurally weak - overlies the anterior branch of middle meningeal artery - if pterion fractures this artery may rupture

Question 33

what can trauma to the pterion lead to?

Answer 33

rupture of the anterior branch of middle meningeal artery which can cause an extramural haematoma (bleed between skull & dura)

Question 34

How can the surface anatomy of the Pterion be described?

Answer 34

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

Question 35

what are Wormian bones?

Answer 35

irregularly shaped small bones found along sutures that occur naturally - most commonly seen on lambdoid sutures

Question 36

What are sutures?

Answer 36

a type of fibrous joint (bound together by Sharpey’s fibres)

Question 37

What are fontanelles?

Answer 37

fibrous membranes that fuse in post-natal life - allow for moulding of cranial shape during birth

Question 38

what is the Vomer bone?

Answer 38

forms the posterior inferior part of nasal septum

Question 39

what passes through the carotid canal?

Answer 39

Interior carotid artery

Question 40

what passes through the Jugular foramen?

Answer 40

- inferior petrosal sinus - sigmoid sinus - posterior meningeal artery - cranial nerves IX, X and XI (glossopharyngeal, vagus and accessory)

Question 41

what passes through the foramen magnum?

Answer 41

- medulla oblongata - venous plexus

Question 42

What passes through the Foramen Spinosum?

Answer 42

- middle meningeal artery - middle meningeal vein - meningeal branch of the mandibular division of trigeminal nerve CNV3

Question 43

how many cervical vertebrae are there?

Answer 43

7 cervical vertebrae - C1 to C7

Question 44

What vertebrae are considered atypical?

Answer 44

C1, C2 and C7

Question 45

What vertebrae are considered typical?

Answer 45

C3 to C6

Question 46

what is vertebrae C1 also known as?

Answer 46

Atlas

Question 47

What are the characteristics of vertebrae C1?

Answer 47

- no body - no spinous process - has an anterior arch and a posterior arch - facets articulate with occipital condyle of skull or dens

Question 48

what is vertebrae C2 also known as?

Answer 48

Axis

Question 49

what are the characteristics of vertebrae C2?

Answer 49

- dens (odontoid process) located on bodies superior surface - spinous process is large and bifid

Question 50

what is characteristic of vertebrae C7?

Answer 50

long spinous process that is NOT bifid

Question 51

what is the function of Alar ligaments?

Answer 51

prevent excessive rotation of head & neck, also connect dens to occipital condyles

Question 52

what is the Hyoid bone?

Answer 52

U-shaped bone found at C3 level in anterior neck - does NOT articulate with any other skeletal elements - suspended by muscles & ligaments

Question 53

How many vertebrae are in the cervical spine?

Answer 53

7

Question 54

What structures does the ligamentum nuchae attach to?

Answer 54

attaches external occipital protuberance & foramen magnum to the spinous processes of clinical vertebrae (to C7)

Question 55

what is the function of the ligamentum nuchae?

Answer 55

supports head & resists flexion, attachment point for muscles