Osteology of the Skull, Cervical Spine & Hyoid Bone Flashcards
Describe the general structure of the skull, including its divisions
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]
What is the neurocranium?
Bony case of brain with a dome-like room (calvaria/skullcap) & a floor (Cranial base)
How many bones are present in the neurocranium?
And what are they..
8 Bones
4 Singular Midline
- Frontal, ethmoid, sphenoid, occipital
2 Sets Bilateral
- Temporal, parietal
What is the viscerocranium?
Collection of bones that make up the facial skeleton
How many bones are present in viscerocranium?
and what are they..
14 (or 15) irregular bones
3 singular midline
- ethmoid, vomer, mandible
6 bilateral sets
- nasal, lacrimal, zygomatic, palatine, maxillae, inferior nasal conchae
what are flat/smooth bones?
Bones formed by intramembranous ossification
what are irregular bones?
Bones formed by endochondral ossification
What are pneumatised bones?
bones with air spaces (air cells or sinuses)
what is the function of pneumatised bones
to reduce weight & also add resonance to our voice
What is the vertex?
Looking at the skull laterally, the vertex is the very top part of the skull
What is the Pterion and whats significant about it?
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
what is lambda?
the point at which the lambdoid sutures and the sagittal suture meet
Superiorly what can be seen on the calvaria?
4 flat bones (2 parietal bones, 1 frontal bone, 1 occipital bone)
What is the bregma?
the point at which the coronal sutures and sagittal sutures cross
what is an inion?
a very small protuberance on the back of the skull near the neck
what are sutures and their use?
They are a type of fibrous joint, and they limit movement from occurring
what are fontanelles?
small spacing between 2 bones (fibrous membrane) where ossification has not yet completed - usually found in infants and fetus
what are the pneumatised bones?
frontal bone
temporal bones
sphenoid bone
ethmoid bones
What is the vomer and where is it?
small, thin, midline bone that divides the nasal cavity
can be seen looking inferiorly to the skull (just behind palatine bone)
what is the ligamentum nuchae and what does it aid in?
attaches external occipital protuberance & foramen magnum to the spinous processes of the cervical vertebrae
supports head & resists flexion (also attachment point for muscles)
what is the cervical spine?
7 vertebrae, concave posteriorly (curves inwards), and allows lateral flexion & rotation
What is a typical cervical vertebrae?
C3-C6
What is an atypical cervical vertebrae?
C7 (also has non-bifid spinous process for attachment of ligamentum nuchae)
where is the vertebral foramen in the cervical spine and what does it enclose?
The large hole in the middle of a vertebral piece which the spinal cord passes through
where is the foramen transversarium and what does it enclose?
vertebral artery, vein and a plexus of sympathetic nerves
What vertebrae have a bifid spinous process?
C2-C6
What is the C1 vertebrae called?
Atlas
What is the C2 vertebrae called?
Axis
Describe the features of the C1 vertebrae (Atlas)?
- No Body
- Spinous process = tubercle (small rounded)
- Has facets to articulate with occipital condyles of skull or dens(round prominence)
Describe the features of the C2 vertebrae (Axis)?
Has a dens/odontoid process which makes contact with the articular facet of C1
What is the atlanto-occipital joint and its use?
the joint between the occipital protuberance and the facets of C1 (atlas).
Allows flexion & extension
what is the use of the lateral atlanto-axial joint
allows rotation of head (side-to-side)
what are alar ligaments?
prevent excessive rotation of head & neck and they connect the dens to occipital condyles
is there a intervertebral disc between C1 & C2?
No
