Lecture 3 Flashcards
sinus
opening of layers to filled with venous blood
Where falx cerebri and tentorium cerebelli meet forms
traiangluar notch opening (tentorial notch)
Structure sits in tentorial notch
midbrain
Structures below tentorial notch
pons, medulla, spinal cord
Function of tentorial notch
allow brainstem structures through middle of brain
Identify this structure
falx cerebri
Identify this structure
tentorium cerebelli
Identify this structure
Superior sagittal sinus
Identify this structure
falx cerebri
Identify this structure
transverse sinus
Identify potential sites o for injury (brainstem)
Can be damaged if displaced by swelling or tumor- soft brainstem pushed against tentorial notch can cause injury
Describe herniation
Severe displacement of CNS structures
describe causes of herniation
additional volume e.g. blood tumours, the soft meterial of the brain moves (brain/brainstem), if pushed into another cpmpartment-> herniation
Subfalcine hernation
herniation below the falx cerebri
Uncal hernation
uncus of the brain moves into the tentorium cerebelli
Identify this herniation
Subfalcine herniation
Identify this herniation
central herniation
Identify this herniation
uncal transtentorial herniation
Identify this herniation
tonsilar herniation
Describe arachnoid layer and loaction
middle layer of meninges, thin wispy (spider like) adheres to inner surface of dura (meningeal layer)
Arachnoid granulation/villi
regions where arachnoid mater push through dura
Identify this layer
Arachnoid mater
Describe pia mater and location
Innermost layer of menigies, adhers to surface of brain- follows gyri and sulci (like shrink wrap)
Identify this layer
Pia mater
Identify the two potential spaces
epidural space, subdural space
Location of epidural space
between inner surface of skull and the dura- above dura
Describe location of sub-dural space
Between meningeal layer of Dura and arachnoid (below meningeal and above arachnoid)
Identify an actual space
Sub arachnoid space
Describe location of subarachnoid space
Between arachnoid and pia mater- contains CSF
Describe trabeculae
Beams of connective tissue holding subarachnoid space, filled with CSF and arterial veins
Forms sagittal sinus
Divergence of dural layers at falx cerebri
Hematoma
Collection of blood
Describe epidural hematoma and cause
Middle meningeal artery runs between dura and skull (artery running through epidural space). Common cause of injury is fracture to temporal bone of skull which can cut meningeal artery. Fracture causes damage to arteries. If arteries bleed into epidural space it can pull pariosteal layer from skull.
Identify this artery
Middle meningeal artery
Identify this space
Epidural space
Three features of epidural hematoma
- Arterial bleed is fast spreading
- Lens shaped appearance- bows inwards
- Can cross the midline- if in superior region
Identify this hematoma
Epidural hematoma
Identify this hematoma
Epidural hematoma
Consequences of epidural hematoma
large epidural hematoma-> increase in intracraneal pressure- displacement (e.g. of brain and ventricle) and possible herniation. Can lead to death, immediate surgery to correct
Describe subdural hematoma and cause
Bridging veins pass through arachnoid and meningeal layer of dura and drain into dural sinuses in subdural space. Common cause of injury is high accelerations or deccelerations (e.g. blow to head, car accident) leading to a shearing between layers and tearing of vessels. Tension on bridging veins, if get torn or ripped bleeding into sinus and start to form in subdural space, pulling arachnoid mater away
Describe features of subdural hematoma
- venous bleed- slow- can develop over a period of time before symptime are prominant
- Crescent shaped- arachnoid not not tighly adhered to meningeal layer-> arachnoid pulls aways more and blood extends through subarachnoid space
- Does not cross the midline- because of falx cerebri- blood enters interhemishpheric fissure
Identify this hematoma
Sub-dural hematoma
Identify this hematoma
Sub-dural hematoma
Consequences of sub-dural hematoma
overtime get displacement and possible herniation
Identify the two types of sub-dural hematoma
chronic subdural hematoma, acute subdural hematoma
Differential acute and chronic subdural hematoma
Acute- blood is hyperdense, therefore brighter on CT scan, associated with major trauma with higher accelerations, accidents, falls
**Chronic- **blood begins to liquify and is less dense, therfore less bright on CT, no major trauma usually in older patients where there is brain shinkage which cause pull/tear on bridging veins, bleeding slow until symptomes aride harder to identify
Identify this type of subdural hematoma
Acute subdural hematoma
Identify this type of subdural hematoma
Chronic subdural hematoma
Describe subarachnoid hematoma and cause
Damage to arteries and veins in subarachnoid space. Common cause of injury:
**nontraumatic- ** rupture of an arterial aneurism- arterial wall bursts and arterial blood into subarachnoid space
**Traumatic **- contusion or other brain injury causing bleeding e.g. car accident, head injury
Describe the movement of CSF into sinuses
CSF flows through granulations into sinuses and enters blood stream- one way movement into sinuses from subarachnoid space. Have turnover of CSF
Describe consequences of subarachnoid hematoma
blood can block, clog granulations- cause increase in CSF increasing pressure in the brain. Significant injury, 25% of people die immediately, some survival if rapidly dealt with
Characteristics of subarachnoid hematoma
- blood widespead across entire space/brain, blood can be seen into fissures
Identify this hematoma
Subarachnoid hematoma
Identify three sites of hematoma
-epidural hematoma
-subdural hematoma
-subarachnoid hematoma
Transtentorial herniation
herniation through tentorial notch
Central herniation
herniation centrally and downward
