S2) Osteology and Radiology of the Skull and Cervical Spine Flashcards
Identify the following structures on an X-Ray of the cervical vertebrae:
- C1-C7 vertebrae
- Vertebral body
- Spinous processes
- Facet joints
- Lamina
- Pedicle
Identify the types of osteological features of skull bones
- Fossae: shallow depressions
- Canal: bony tunnel
- Foramina: round holes
- Fissures: narrow slits
The bones of the skull can be broadly divided into two groups.
Identify them
- Neurocranium (8 bones)
- Viscerocranium (14 bones)
Describe the function and components of the neurocranium
- Function: encase and protect the brain
- Components:
I. Calvaria
II. Cranial floor
III. Cranial cavity
Describe the development of the neurocranium
- Calvaria begin as membranes i.e. intramembranous ossification
- Cranial floor begin as cartilage i.e. endochondral ossification
Describe the function and components of the viscerocranium
- Contents: facial skeleton and the jaw
- Function: surrounds oral cavity, pharynx and upper respiratory passages
Describe the development of the viscerocranium
- Bones begin as membranes or cartilage and ossify
- Most structures develop from the pharyngeal arches (1&2)
Why are there foramina, fissures and canals in the neurocranium?
- To allow the neurocranium to communicate with other structures of the head and neck
- To allow passage of blood vessels and cranial nerves
Three ‘bowl‐shaped’ depressions form the cranial floor.
Identify them and describe their osteological features
Anterior, middle and posterior cranial fossae – each fossae has series of foramina, fissures and/or canals
What is the significance of the trilaminar arrangement of the bones of cavaria?
Confers protective strength without adding significant weight
What are sutures?
Sutures are fibrous joints which are found at intersections between bones
Identify the names of the most important sutures
Describe the features of the bones forming a suture joint
Edges of bones forming suture joint are ‘serrated’ to prevent slippage and movement
Describe the development of suture joints
- Growth at sutures stops around puberty
- Then are gradually obliterated from inside → outside
What are fontanelles?
Fontanelles are large areas of unossified membranous gaps between flat bones of calvaria
What is the function of fontanelles?
- Allow for alteration of the skull size and shape during childbirth
- Permit growth of infant brain
When do the fontanelles fuse?
Fontanelles fuse in early infancy:
- Anterior: ~18 months ‐ 2 years
- Posterior: ~1 ‐ 3 months
What is the early fusion of fontanelles called?
Craniosyntosis is the early fusion of fontanelles and sutures
Why is the anterior fontanelle clinically useful when examining babies?
Inspection and gentle palpation of anterior fontanelle can be used to assess intracranial pressure and state of hydration
What is required to fracture a skull?
Why are the incidence in skull fractures varied?
- Significant trauma and force required to fracture skull
- Thickness of cranial bones varies, resistance to fracture therefore varies
What is the main concern with regards to skull fractures?
Skull fractures are associated with higher incidence of intracranial pathology (injury to brain, blood vessels, cranial nerves) and neurological deficits
Can one still have an intracranial injury without a skull fracture?
How do we confirm this?
Yes, CT scanning should be performed in all patients with known or suspected skull fractures to identify any intracranial injuries
Identify and describe the two main fracture types
- Linear fractures: fracture passes full thickness of skull, fairly straight, involve no bone displacement
- Depressed fractures: fragment is displaced inwards towards the brain
What are fractures involving the cranial base called?
Basilar skull fractures
