Anatomy of Space Occupying Lesions Flashcards
Any SOL can cause a rise in?
ICP
SOL can be acute or subacute. Define these.
Acute - happens quickly e.g blood leak
Subacute - happens slower e.g growing tumour
What can ICP result in?
Herniation
What is the name of the hypothesis?
Monroe-Kellie
What does thee hypothesis state?
As the skull is a closed box, any SOL or increase involute will increase pressure
Name the 5 layers of skin of the scalp from superficial to deep.
S - skin C - connective tissue A - aponeurosis L - loose connective tissue P - pericranium
What layer contains the blood supply to the scalp?
Connective tissue
What is the pericranium?
Periosteum
Outer membrane of bone that is responsible for bone formation
What are the 2 main arteries of the scalp?
External carotid artery
Internal carotid artery
What do the main arteries of the skin of the scalp form?
Anastomosis
Describe the aponeurosis.
Tendinous layer
What muscles does the aponeurosis of the scalp join?
Frontalis muscle at the front with the occipitals muscle at the back
What is the function of sutures of the skull?
Help prevent skull fractures from spreading
What bones make up the pterion?
Frontal
Parietal
Occipital
Temporal
What is the thinnest part of the skull?
Pterion
What artery lies beneath the pterion? Why is this not good?
Middle meningeal artery
The pterion is very thin and easily fractured which may damage the artery and lead to haemorrhage
Look at slide 6
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What is meningitis?
Bacterial or viral infection of the meninges
What does the dura mater enclose?
Dural venous sinuses
What nerve supplies sensory innervation to the dura mater?
CN V
What is an important feature of the arachnoid mater. Describe this.
Arachnoid granulations
These are projections of the arachnoid mater up into the dural venous sinuses which reabsorb CSF
Where is CSF contained?
Subarachnoid space
What does dura mater adhere to?
Internal surface of the skull
What is the diaphragm sellae?
A tough sheet of dura mater which forms a roof over the pituitary fossa
What is the name of the tough sheet of dura mater that covers the cerebellum?
Tentorium cerebelli
The tentorium cerebelli has a gap to allow a structure to pass through. What is this structure?
Brainstem
What does the tentorium cerebelli attach to?
Ridges of the petrous temporal bones
Name the 3 layers of the dura mater.
Diaphragm sellae
Tentorium cerebelli
Falx cerebri
What is the location of the falx cerebri?
Sits between the centre of both right and left cerebral hemispheres
Describe the veins in the danger triangle of the face.
Thick
Valveless
What isn’t a good thing to do in the danger triangle of the face? Why?
Squeeze a spot
It can introduce bacteria into the veins which will then travel into the cavernous sinus and allow bacteria to accumulate in the cranial cavity
What is the function of the cerebral veins? Where do they drain into?
Drain venous blood from the brain into the dural venous sinus
Describe the sigmoid sinus.
‘S’ shaped sinus drains into the internal jugular vein at the jugular foramen
What is it known as when many dural venous sinuses come together?
Confluence
Describe the confluence of sinuses.
In the midline at the internal occipital protuberance which is deep to the external occipital protuberance
The vertebral arteries are a branch of what artery?
Subclavian arteries
The internal carotid arteries are a branch of what artery?
Common carotid arteries
The internal carotid artery becomes internal via the carotid canal and supplies what?
Brain
The external carotid artery stays external and supplies what?
Neck
Face
Scalp
Left/Right anterior cerebral artery supplies?
Medial cerebral hemisphere
Left/Right middle cerebral artery supplies?
Lateral cerebral hemisphere
Left/Right posterior cerebral artery supplies?
Posterior cerebral hemispheres
Visual cortex
Right vertebral + Left vertebral artery =
Basilar artery
At what level does the spinal cord end?
L2
At what level does the subarachnoid space end?
S2
Where is CSF produced?
In the choroid plexus of the ventricles
Where is CSF reabsorbed?
In the arachnoid granulations of the dural venous sinuses
What procedure is done to obtain a sample of CSF?
Lumbar puncture
What level is safe to perform a lumbar puncture?
L2-L5
L3-L4 (most common)
Outline the route of CSF.
- Secreted by choroid plexus
- Right and left lateral ventricles
- Foramen on Monroe
- 3rd ventricle
- Cerebral aquaduct
- 4th ventricle
- Subarachnoid space (or some to central canal)
- Arachnoid granulations to dural venous sinus
What is hydrocephalus?
Excess production, obstruction to flow or inadequate reabsorption leads to increased CSF
How is hydrocephalus treated? Explain this.
Ventricular peritoneal shunt
The shunt catheter is “tunnelled” beneath the skin of the neck and chest then sited within the peritoneal cavity
Describe an extra-dural haemorrhage. What vessel is affected?
Bleeding between bone and dura
Trauma to pterion
Middle meningeal artery
Describe a subdural haemorrhage. What vessel is affected?
Bleeding between dura and arachnoid
Falls in the elderly/those who drink
Cerebral veins
Describe a subarachnoid haemorrhage. What vessel is affected?
Into CSF of subarachnoid space
Ruptured CIRCLE OF WILLIS’
‘BERRY ANEURYSM’
Congenital aneurysm
Describe the stages of epidural anaesthesia.
- Catheter passed through supraspinous then infraspinous ligaments
- Then ligament flavum
- Then epidural space
What is contained within the epidural space?
Fat and veins
Describe the stages of a lumbar puncture.
- Catheter passed through supraspinous then infraspinous ligaments
- Then ligament flavum
- Then epidural space
- Dura mater
- Arachnoid mater
- Subarachnoid space
- CSF obtained
What does damage to the epidural venous plexus result in?
Epidural haematoma compressing the spinal cord or caudal equina