Anatomy Practical 3 Flashcards
how many layers does the scalp consist of
5 layers
name the 5 layers of the skull
- skin
- connective tissue
- aponeurosis
- loose connective tissue
- pericranium
describe the 5 layers of the skull
Skin:
thin, has many sweat & sebaceous glands, abundant arterial supply & venous drainage
Connective tissue:
thick and richly vascularised and is also well supplied with nerves
Aponeurosis:
strong tendinous sheet between muscle bellies of frontalis and occiptalis
Loose connective tissue:
sponge like has potential to distend with many spaces; allows free movement of scalp
Pericranium:
dense connective tissue, periosteum of the calvaria (Skull bones)
what skull bones make up the pterion
frontal
spehniod
parietal
temporal
what structures pass through the superior orbital fissure
oculomotor nerve (III) trochlear nerve (IV) lacrimal, frontal and nasociliary branches of ophthalmic (V1
what structures pass through the inferior oribital fissure
inferior orbital vessels
Inferior division of ophthalmic vein
what are the three layers of the meninges
dura mater
arachnoid mater
pia mater
describe the dura mater
- most outermost layer of the meninges
- dense fibrous membrane composed of a tough external layer and an inner meningeal layer
- inner layer draws away from the outer layer to form dural folds that separate different brain regions from each other
- the largest of the septa is the cerebral falx
what does the cerebral falx do
- separates the two cerebral hemispheres
- the falx becomes continous with the cerebellum tentorium
what does the cerebellum tentorium do
- the cerebellum tentorium separates the cerebllum from the occipital lobe of the cortex
- it covers the posterior fossa structures and supports the occipital and temporal lobes
what is the gap in the falx
- it contains a gap called the tentorial notch
what passes through the tentorial notch
- brainstem and blood vessels pass to enter the middle cranial fossa
what can cause herniate through the tentorial notch
Tumours that occupy this space raise the intracranial pressure and may cause herniation of the temporal lobe (uncus) through this space.
what is the pia attached to
- attached to the brain
what does the subarachnoid space contain
- a network of connective tissue strands
- blood vessels
- nerves and CSF
- they have arachnoid granulations
what type of MRI imaging are there
T1 or T2 weighting - refers to measurements of energy absorbance and release
describe T1
- T1 CSF bone air and blood are black
- fat and bone marrow are white
describe T2
- CSF, bone, air and bloid are white
- fat and bone marrow are black
what is T1 used for whereas what is T2 used for
T1 images are used to reveal soft tissue damage whereas T2 is used for visualising damage involving fluid containing structures
what is the usual cause of death of head injury
- raised intracranial pressure - either the result of brain swelling or of a haemorrhage accumulating inside the skull
what does potential disability
- damage to axons
- hypoxic-ischaemic damage
what are the two important mechanisms involved in head injury
- impact to the head
- movement of the brain
how can you classify the damage seen in head injury in a number of ways
focal or diffuse
describe a focal brain injury
- indicates pathology that can be seen on a CT or MRI scan
describe a diffuse brain injury
- diffuse brain injury refers to microscopic damage which cannot be demonstrated by any of the current imaging techniques but which clinicians diagnose because they have an unconscious patient whose scan shows very little obvious damage
describe a depressed fracture
- a fracture in which an area of the skull i driven inwards