Ostelogy Of Skull Flashcards
What kind of ossification do flat bones from from
Intramembranous ossification ( no cartilage precursor)
- mesenchymal cells differentiate directly into odontoblasts which then becomes bone there is no cartilage precursor involved.
Irregular bones form from which kind of ossification ?
Endochondral ossification
- mesenchymal cells differentiate into chondroblasts which lay down hyaline cartilage which is then replaced by bone.
Define Pneumatised bones and why do they exist?
These are bones which air spaces ( air cells or sinuses). We have these to reduce the weight of our skull and provide resonances our voice.
How many bones are present in the skull excluding the ossicles of the ear
22
What two processes form the zygomatic arch?
Temporal process of zygomatic bone and the zygomatic process of the temporal bone
Name the superior and posterior borders of the temporal fossa
Superior and inferior temporal lines
Anterior border of the temporal fossa
Frontal process of zygomatic bone and zygomatic process of frontal Bone
Inferior border of temporal bone
Infra-temporal crest deep. To. Zygomatic arch
What is the Nasion?
Where the frontal nasal and internal sutures meet
Where would you find the glabella
Smooth part of the frontal bone between the eyebrows
Name the star shaped junction where 3 sutures between the occipital, parietal and temporal bones meet
Asterion
The name of the junction between the lamboid and saggitall sutures
Lambda
The junction of the coronal and saggital sutures is
Bregma
The inion is what
The most prominent part of the occipital tuberance
What is the Pterion
Represents the junction of the 4 skull bones ( greater wing of the sphenoid, frontal, parietal and sphenoid)
What is the significance of trauma to the pterion
Structurally weak and it overlies the anterior branch of the middle meningeal artery, so trauma can lead to a epidural haematoma
What is a sutural bone and where are they most common
It is a small island of bone within a coronal suture ( usually in lamboid) - highlights the way the skull grows and expands allowing for development/ birthing
Where does the nuchal ligament attach
The inferior nuchal line ( part of occipital bone)
What is a suture in the skull and why would it ever move
It is a type of fibrous joint, that is a synarthrosis. However it will allow for minimal movement for biomedical protection so to Absorb force
What is a synarthosis
Joint where no movement occurs
Fontaelles?
Flat bones are separated by fibrous membranes that fuse in post natal life. ( will have until about 18mnths-2 years).
Posterior - close in first year
Initially to allow for moving of cranial shape to facilitate birth and then to allow post natal growth
What passes the jugular foramen
The internal jugular vein as well as CN9,10,11
What is special about foramen lacerum?
This is an artefact of dry bone because in life it is closed by cartilage because internal carotid artery and carotid plexus pass it .
What does the ligamentum nuchae do
Attaches external occipital protuberance and foramen magnum to spinous process of cervical vertebrae
Supports head and resists flexion
What is the suprasinous ligament.
Strong fibrous cord which connects C7 to L3/4
What are the typical cervical vertebrae
C3-C6
What is the function of the Foramen Transversarium
Cervical vertebrae are the only ones with this feature, this is where the vertebral artery passes.
Not usually in C7 as is too small
How does C7 attach to ligamenutm nuchae
Non bifed spinous process
What is feature of the spinous process in C2-C6 allows for greater area for muscle attachment
They are bifend
Function of dens in axis
Tooth like structure which aids in a pivot point for the atlantooccipital joint and atlas
What is the atlantooccipital joint
Articulation between atlas and occipital bone, it is a pivot joint allowing for flexion and extension.
What is the joint called between atlas and axis and what does it do
atlanto-axial joint and it is a condyloid joint, it allows for the rotation of the head ( shaking your head to say no etc) .
What do the lateral atlanto-axial joint and pivot point of dens allow for, which ligament assists this
Allows rotation of head ( side to side)
Assisted by the transverse ligament of atlas holding dens in position
What is the function of the alar ligaments
Prevent excessive rotation of head and neck by connecting dens to occipital condoyles
Where is the hyoid bone found
At the level of C3 in the neck
Does not articulate with any skeletal elements in the head and neck
What does the hyoid bone do and what does it connect
Helps keep the airway open
Connects with oral cavity with pharnyx posterioly and larynx inferiorly
What is the function of the parietal foreman
Allows for passage of emissary veins connecting superficial veins to deeper veins
What is the function of the vertical foramen
Allows for the spinal cord to pass
