Osteology of the head and neck Flashcards
What two components are there to the bones of the head and neck?
Cervical vertebrae Skull
Label the below image with:
- each vertebral body
- spinous processes
- lamina
- pedicles
- facet joints
- dens
- intervertebral discs
Why would you do an open mouth Xray in a supsected C spine injury?
To look at the Dens and C1 lateral masses
How many bones are in the skull?
22
What is a fossa?
Shallow depression in a bone
Whats a boney tunnel called?
A canal
How do you distinguish between a foramina and fissure?
Foramina are round holes
Fissures are slits
Which 3 suture lines are important to recognise when veiwing the skull from above and behind?
Saggital
Coronal
Lamboid
Label the bones in the image
How many bones form the neurocranium?
8 bones
What is the calvaria?
The skull cap- remember this part develpes from intramemebranous ossification
How does the cranial floor form?
Endochondral ossification
What is the viscerocranium?
The parts of the skull that do not directly encase th brain. The facial skeleton and jaw.
The pharyngeal arches (1&2) give rise to which osteological featurs of the head and neck?
Viscerocranium
Which 3 fossa are seen on the neurocranial floow?
Anterior cranial fossa for the frontal lobe
Middle cranial fossa for the temporal lobe
Posterior cranial fossa for the occipital lobe
What causes grooves in the skull?
Dural venous sinuses
What is the role of fissures, canals and foramina?
Allow structers of the cranium to communiate with the rest of the head and neck
Bones of the Calvaria have a trilaminar arrangement, please list the layers from superficial to deep.
Compact outer bone
Spongiform bone
Compact inner bone
Why is trilaminar bone arrangement in the calvaria important?
Increases strenth without massively increasing the weight
What are sutures?
Fibrous joints between bones which appear serrated to stop slippage.
When does growth at sutures stop and what happens after?
Puberty.
The suture is slowly olbiterated inside to outside
The outer table of bone is covered by what and whats tte function of the covering?
Periosteum
Lines the bone and sticks the scalp to the skull. Rememebr is adheres strongly at the suture lines but is continuus with the inner table periosteum.
What is a cephalohaematoma?
Subperiosteal bleed- note it wont cross the suture lines so it looks like a round bump on the head (commonly seen after vaginal delivery in new borns). No risk to brain as cant cross the suture lines
In a subaponeurotic bleed what is notable different to a subperiosteal bleed?
This bleed (subgaleal bleed) is not limited by the suture lines
What are frontanelles?
Large areas of memebrane between bones in newborns. They let the skull chage size and shape in delivery and will give room for brain growth in childhood.
When should frontanelles fuse and what is the name given to premature fusion?
Anterior 18/12-24/12
Posterior 1-3/12
Craniosyntosis
Why are frontanelles clinically useful?
The frontanelle is a bit convex shaped in healthy babies. The anterior one can be inspected and gently plapated to assess hydration and ICP.
What is the diploic cavity in the skull?
The area of spongiform bone in the calavaria
Where is the orbit likely to fracture (weakest parts)?
Medial and inferior borders
Which area of the temporal bone is prone to fracture because it is very thin?
Petrous part
Why do we worry about skull fractures?
Risk of intracranial injury (brain, BVS and cranial nerves)
Don’t forget the skull doesnt have to fracture for the brain to be injured. The presence of a skull fracture does increase the likelyhoof of intercranial pathology however
Any patient with a skull fracture should have what imaging to rule out intercranial injury?
Head CT
What type of skull fracture is depicted below
Depressed
What does a linear skull fracture look like?
Full thickness straight crack in the skull with no bone displacement
What clinical signs indicate basilar skull fracture?
Racoons eyes
Bruising over mastid process- Battle sign
Blood behind ear drum - Haemotymponin
What is a basilar skull fracture and what additional risks do they posses?
Cranial base fractures
Cranial nerve injuries and CSF leakage
What is the pterion and why is it important?
Thinnest part of the skull which lies just over the middle meningeal artery
What type of heamorrhage would be seen if the pterion fractured and ruptured the middle meningeal artery?
Extra dural heamorrahage
Which facial bones commonly fracture?
Nasal
Zygomatic
Mandibular
