2) Osteology and Radiology Flashcards
What can the cranium be split up into?
Neurocranium - housing brain
Viscerocranium - facial skeleton
What does the neurocranium consist of?
Calvaria (roof) and base of skull
What bones form the calvarium?
Frontal, occipital and two parietal bones
What bones form the cranial base?
Frontal, sphenoid, ethmoid, occipital, parietal and temporal bones
How are the bones of the calvaria arranged?
And why?
Tri lamina arrangement, two layers of compact bone separated by layer of spongy bone (diploe)
Conveys strength without adding significant weight
Give examples of bones in the facial skeleton:
Zygomatic, maxilla, mandible,. lacrimal, nasal, sphenoid, vomer and palatine bone
What are the two types of joint in the skull?
Give an example of each
Immobile: joined by fibrous tissue e.g. sutures
Mobile: only one, temporomandibular joint
Give examples of sutures in the skull:
Coronal: between parietal and frontal
Squamous: temporal and parietal
Sagittal: between parietal bones
Lambdoid: between parital and occipital
What happens to the sutures as we age?
Ossify
What are fontanelles?
Membranous areas of unfused skull in babies
What is the function of fontanelles?
Allow for brain growth and flexibility eases passage through birth canal
What are the names of the fused anterior and posterior fontanelles?
Bregma
Lambda
What is the significance of sunken fontanelles?
Dehydration or malnutrition
What is the significance of bulging fontanelles?
Raised intracranial pressure or meningitis
What is the significance of enlarged fontanelles?
Premature birth or Down’s syndrome
What is the pterion?
Lateral aspect of skull where temporal, parietal, frontal and sphenoid bones meet. Thinnest part of skull
What can a fracture at the pterion lead to?
Injury of anterior branch of middle meningeal artery causing extradural haematoma
Why is it called an extradural haematoma?
Blood vessels run between periosteum and dura mater so dura is pushed away from bone by blood and pressure exerted on brain
What are the 3 areas of the cranial floor?
Anterior, middle and posterior floor
What allows neurovascular structures to pass into cranial compartment?
Foramina of cranial floor
What causes skull fractures?
Severe trauma, blows/impact injury
What are the consequences of skull fractures?
Damage underlying brain, blood vessels or cause intracranial haematoma
What is the primary investigation used in suspected skull fractures?
CT scan
What causes basilar skull fractures?
Force transmitted through vertebral column
What suggestive signs of a basilar skull fracture?
Battle’s sign - bruising of mastoid process
Raccoon eyes - bilateral bruising around eyes
Haemotympanum - blood behind ear drum
CSF leakage from nose and ear
What are the complications of basilar skull fractures?
Meningeal tears
Cranial nerve palsies
Meningitis
What causes facial skeleton fractures?
Road traffic collisions, fights and falls
What bones of the facial skeleton are commonly fractured?
Nasal, zygomatic and mandible
If a patient has a suspected neck injury, what should be done?
Spinal immobilisation
What investigations can confirm a spinal fracture in adults and children?
CT in adult
X-ray/MRI in children
What is a Jefferson’s fracture and what causes it?
Burst fracture of C1, combination of anterior and posterior arch fractures. Caused by axial compression
What is a Hangman’s fracture and what causes it?
Bilateral fracture of posterior arch of C2 and disruption of C2/3 junction. Caused by hyperextension of neck
What are the complications of Hangman’s fractures?
May extend to transverse foramen and damage vertebral arteries
C2 may displace causing spinal cord damage
What are vertebral crush fractures and what causes them?
Fractures of vertebral bodies causes by osteoporosis, hyperflexion and various others
What degenerative disease can affect the spine?
Osteoarthritis -> cervical spondylosis
What are the features of cervical spondylosis?
Osteophytes Facet joint hypertrophy Disc herniation Disc space narrowing Sclerosis of end plates
What is cervical spondylotic radiculopathy and what can it lead to?
Nerve root impingement
Dermatomal arm pain +/- mild weakness and sensory loss
What is cervical spondylotic myelopathy and what can it lead to?
Spinal cord compression
Loss of function and fine motor skills in upper limb
