Osteology of the Skull, Cervical Spine & Hyoid Bone

Question 1

Describe the general structure of the skull, including its divisions

Answer 1

Skull also known as cranium, is composed of the mandible, neurocranium, & viscerocranium (with a total of 22 bones in the adult, excluding ossicles of ear) [28 with ossicles]

Question 2

What is the neurocranium?

Answer 2

Bony case of brain with a dome-like room (calvaria/skullcap) & a floor (Cranial base)

Question 3

How many bones are present in the neurocranium?
And what are they..

Answer 3

8 Bones
4 Singular Midline
- Frontal, ethmoid, sphenoid, occipital

2 Sets Bilateral
- Temporal, parietal

Question 4

What is the viscerocranium?

Answer 4

Collection of bones that make up the facial skeleton

Question 5

How many bones are present in viscerocranium?
and what are they..

Answer 5

14 (or 15) irregular bones
3 singular midline
- ethmoid, vomer, mandible

6 bilateral sets
- nasal, lacrimal, zygomatic, palatine, maxillae, inferior nasal conchae

Question 6

what are flat/smooth bones?

Answer 6

Bones formed by intramembranous ossification

Question 7

what are irregular bones?

Answer 7

Bones formed by endochondral ossification

Question 8

What are pneumatised bones?

Answer 8

bones with air spaces (air cells or sinuses)

Question 9

what is the function of pneumatised bones

Answer 9

to reduce weight & also add resonance to our voice

Question 10

What is the vertex?

Answer 10

Looking at the skull laterally, the vertex is the very top part of the skull

Question 11

What is the Pterion and whats significant about it?

Answer 11

A H-shaped junction of sutures on the side of the skull
Overlies ANTERIOR BRANCH OF MIDDLE MENINGEAL ARTERY

Structurally weak and trauma can lead to a extradural haematoma

Question 12

what is lambda?

Answer 12

the point at which the lambdoid sutures and the sagittal suture meet

Question 13

Superiorly what can be seen on the calvaria?

Answer 13

4 flat bones (2 parietal bones, 1 frontal bone, 1 occipital bone)

Question 14

What is the bregma?

Answer 14

the point at which the coronal sutures and sagittal sutures cross

Question 15

what is an inion?

Answer 15

a very small protuberance on the back of the skull near the neck

Question 16

what are sutures and their use?

Answer 16

They are a type of fibrous joint, and they limit movement from occurring

Question 17

what are fontanelles?

Answer 17

small spacing between 2 bones (fibrous membrane) where ossification has not yet completed - usually found in infants and fetus

Question 18

what are the pneumatised bones?

Answer 18

frontal bone
temporal bones
sphenoid bone
ethmoid bones

Question 19

What is the vomer and where is it?

Answer 19

small, thin, midline bone that divides the nasal cavity

can be seen looking inferiorly to the skull (just behind palatine bone)

Question 20

what is the ligamentum nuchae and what does it aid in?

Answer 20

attaches external occipital protuberance & foramen magnum to the spinous processes of the cervical vertebrae

supports head & resists flexion (also attachment point for muscles)

Question 21

what is the cervical spine?

Answer 21

7 vertebrae, concave posteriorly (curves inwards), and allows lateral flexion & rotation

Question 22

What is a typical cervical vertebrae?

Answer 22

C3-C6

Question 23

What is an atypical cervical vertebrae?

Answer 23

C7 (also has non-bifid spinous process for attachment of ligamentum nuchae)

Question 24

where is the vertebral foramen in the cervical spine and what does it enclose?

Answer 24

The large hole in the middle of a vertebral piece which the spinal cord passes through

Question 25

where is the foramen transversarium and what does it enclose?

Answer 25

vertebral artery, vein and a plexus of sympathetic nerves

Question 26

What vertebrae have a bifid spinous process?

Answer 26

C2-C6

Question 27

What is the C1 vertebrae called?

Answer 27

Atlas

Question 28

What is the C2 vertebrae called?

Answer 28

Axis

Question 29

Describe the features of the C1 vertebrae (Atlas)?

Answer 29

• No Body
• Spinous process = tubercle (small rounded)
• Has facets to articulate with occipital condyles of skull or dens(round prominence)

Question 30

Describe the features of the C2 vertebrae (Axis)?

Answer 30

Has a dens/odontoid process which makes contact with the articular facet of C1

Question 31

What is the atlanto-occipital joint and its use?

Answer 31

the joint between the occipital protuberance and the facets of C1 (atlas).

Allows flexion & extension

Question 32

what is the use of the lateral atlanto-axial joint

Answer 32

allows rotation of head (side-to-side)

Question 33

what are alar ligaments?

Answer 33

prevent excessive rotation of head & neck and they connect the dens to occipital condyles

Question 34

is there a intervertebral disc between C1 & C2?

Answer 34

No