Lecture 7 - Ventricular and dura venous systems Flashcards
What are the 4 types of hemorrhage in the neurocranium that can compromise brain functions?
Intraparenchymal
subarachnoid
Epidural
Subdural
What is the worst kind of hemorrhage?
Epidural - MEDICAL EMERGENCY
What are the three layers of meninges?
1 - dura mater
2 - arachnoid mater
3 - pia mater
What are the arachnoid trabeculae?
columns connecting arachnoid mater to pia mater
- spider web-like
What are the two layers of the dura mater?
- periosteal (around the bone, is a membrane that covers the cranium)
- meningeal (continuous to dura mater, covers our spinal cord from dural sac)
What is the most outer layer of the brain? (cannot be seperated from it)
pia mater
- PART OF THE BRAIN
What is the epidural space?
between bone and periosteal
Does the epidural space exist normally?
NO - only when we have bleeding, pushes it away
- between the periosteal matter and neurocranium
Where is the subdural space?
between the meningeal dura and arachnoid mater
- DOESNT EXIST NORMALLY
What is the subarachnoid space?
between the arachnoid and pia mater
- FILLED WITH CSF
Where is the falx cerebri?
in the longitudinal fissure
- separates 2 hemispheres of the cerebrum
Where is the falx cerebelli?
in the groove posterior to the cerebellum
Where is the tentorium cerebelli?
In the transverse fissure
Where is the diaphragma sellae?
sealing the sella turcica, separates pituitary gland from hypothalamus
What 2 meningeal foldings are in the sagittal plane?
- falx cerebri
- falx cerebelli
What 2 meningeal foldings are in the transverse plane?
- tentorium cerebelli
- diaphragm sellae
Where is the superior sagittal sinus?
the superior border of the falx cerebri
Where is the inferior sagittal sinus?
the inferior border of the falx cerebri
What vein does the ISS run with?
the great cerebral vein
What forms the straight sinus?
the ISS and great cerebral vein flow together
What forms the confluence of sinuses?
the SSS, straight sinus, and occipital sinus flow together
What does the occipital sinus run in?
the falx cerebelli
What is the transverse sinus?
runs to either side horizontally in the lateral border of straight sinus and tentorium cerebelli and periosteal dura mater, descends into posterior cranial fossa through jugular foramen
What is the sigmoid sinus?
shaped like S, formed internal jugular vein
What surrounds the sellae tursica?
cavernous sinus
Where is the dangerous triangle?
around nose, upper lip
What is dangerous about the dangerous triangle?
the venous blood flows to the cavernous sinus which will spread the infection to the cranium
What can happen with an infection on the scalp?
the emissary veins take venous blood from the scalp to the SSS
Which meninge has somatosensory innervation?
ONLY the dura mater
What is the dura mater innervated by?
most parts by the trigeminal nerve divisions
V1 - ophthalmic provides MOST of the somatosensory innervation
What area will a craniotomy be performed in?
the area of sparse innervation in the dura mater
What is the posterior cranial fossa dura innervated by?
C2/C3 - sensory divisions ascend through vagus nerve (CN X) or glossopharyngeal nerve (CN IX) that goes into posterior cranial fossa
Why is it important that C2/C3 innervates the posterior cranial fossa dura?
cervicogenic headaches with neck problems!
If a patient suffers from a right PCA ischemic stroke, which signs/symptoms will the patient most likely present?
PCA supplies inferior temporal lobe and occipital lobe
- left visual fields
- Memory
> most impacted
What area of the brain can cause a silent/lacunar stroke?
the thalamus, which is supplied by the PCA
How are the lateral and 3rd ventricles formed?
invasion of blood vessels through parenchymal structures, blood vesseal cause expansion of choroid plexus, which forms 2 lateral and one 3rd ventricle
What connects the 2 lateral and 3rd ventricle?
the foramen of monro
What creates the 4th ventricle?
the posterior alar plate of the brainstem opens and expands
What is BBB?
blood brain barrier
Why is the BBB important?
blood vessels don’t have direct contact with our brain tissues, separates vascular system from brain structures
What are the main functions CSF?
- buoyance
- insulation
- waste diffusion
What do ependymal cells do?
form tight junctions, extract nutrients/ions from plasma, secrete out CSF
What is CSF NOT good for?
nutrition
- doesn’t provide nutrients to brain structures, astrocytes wrap around capillaries and extract nutrients directly from blood vessels
What does foramen of Monro connect?
the lateral ventricle(s) and 3rd ventricle
“bird head”
What is another term for foramen of monro?
interventricular foramen
What lobe contains the anterior horn of the lateral ventricle?
the frontal/limbic lobe
What lobe contains the body of the lateral ventricle?
frontal/limbic lobe
What lobe contains the atrium of the ventricles?
parietal and limbic lobes
What lobe contains the occipital horn of the lateral ventricle?
occipital lobe
What does the cerebral aqueduct connect?
the 3rd ventricle connects to the 4th ventricle through here
- in the midbrain
What is the lateral aperture also known as?
the foramen of luschka
What is the medial aperture also known as?
foramen of magendie
What lobe contains the temporal horn of lateral ventricle?
temporal lobe
What is the interpeduncular cistern?
anterior to the midbrain, have descending tracts in anterior midbrain in the cerebral peduncle, for which this is named
What is the quadrigeminal cistern?
posterior to midbrain, 2 superior and 2 inferior colliculi, 4 total (quad) which gives this its name
What is the pontine cistern?
a container near the pons
What is the cisterna magna?
close to foramen magnum
What can an enlarged cistern indicate?
atrophied brainstem/cerebellum
What happens to CSF during systole?
ventricles push CSF into subarachnoid space
- from rostral to caudal subarachnoid space
What happens to CSF during diastole?
heart relaxes, CSF pulled into subarachnoid space to the ventricles
- from caudal to rostral subarachnoid space
Where are the major dural venous sinuses locate din the meningeal foldings?
- Falx cerebri: SSS and ISS
- Falx cerebelli: occipital sinus
- Tentorium cereblli: Straight sinus and transverse sinus
What is hydrocephalus?
CSF drainage blocked
- increased CSF pressure: above 7-15mmHg
What happens with hydrocephalus if foramen of Monro is blocked?
the lateral ventricle on the side of the blockage will expand, affect that side of the brains functions
What happens with hyrdrocephalus if the cerebral aqueduct is blocked?
the 2 lateral ventricles and the 3rd ventricle will lead to all 3 being blocked
What happens with hydrocephalus if the formen of luschka and madgendie are blocked?
all 4 ventricles will be enlarged
What happens if global function is compromised with hydrocephalus?
a ventriculoperitoneal shunt is required
What is a ventriculoperitoneal shunt?
a shunt from the ventricles to the peritoneum in abdominal cavity, drains extra amount of CSF directly into peritoneal cavity.
What is normal pressure hydrocephalus (NPH)?
- hydrocephalus with pressure still 7-15mmHg
- Age-related
- tons of possible causes
What are the NPH triads?
three “Ws”
- Wacky (lost thickness of cerebral cortex, many brain functions compromised)
- Wet (incontinence)
- Wobbly (ataxia, gait apraxia)
How does CSF drain to venous sinuses?
- active transportation and secretion
- passive diffusion fenestration along the endothelia
How can CSF be actively transported and secreted?
- endothelial cells will swallow CSF, get out from “other side”
How can CSF drain through passive diffusion?
- endothelia form junctions but small gaps(fenestration). Because of the gaps, CSF can get out purely based on pressure as in diastole. Pressure of the CSF is higher than pressure of the venous blood in SSS
What is an epidural hemorrhage?
mainly meningeal artery disruption: convex hematoma
- bc of artery has much higher pressure, pushes the periosteal dura mater off, causes biconcave bleeding (LEMON)
What is the pterion?
weakest point around the neurocranium
Where can an epidural hemorrhage occur more?
under the calvaria part (sutures, external occipital protuberance, superior nucal line)
What will generally happen with an epidural hemorrhage?
pt will lose consciousness for a short duration, recover and act normally, then pass out again
- by the time they pass out again = too late
What is a subdural hemorrhage?
- intradural hemorrhage
- bridging vein disruption: concave
- BANANA
- shaking baby syndrome
- will cause a severe HA
How does cerebrospinal fluid drain out of the ventricular system during systole?
- out of ventricles
- from rostral to caudal in the subarachnoid space
Which typical signs/symptoms will a patient with normal pressure hydrocephalus present with?
3 w’s
- wacky: impaired cognition
- wet: incontinence
- wobbly: ataxia
What percentage of blood supply for the whole body goes to the brain?
20%