Ventricles and Meninges Flashcards
Clear, colorless fluid with a volume of approximately 140 mL
Cerebrospinal Fuid (CSF)
CSF is replaced
2-3 times per day
CSF is located in the subarachnoid space around the brain and in the ventricles where it is produced by the
Choroid plexus
Protects against sudden movements and maintains constant intracranial pressure
CSF
Has some antibacterial properties and controls the extracellular fluid of the brain
CSF
Allow free movement of CSF between ventricles
Ependymal cells w/ adhering junctions
Enables exchange of CSF outside of the brain
Pia matter
CSF is produced by the
Choroid plexus
The choroid plexus is located on the edges of the
Lateral ventricles, the 3rd ventricle, and the 4th ventricle
Choroidal Arteries penetrate into ventricles and form the
Choroid plexus
The choroid plexus is made up of which three components?
Endothelial wall of choroidal capillaries, scattered pial cells, and choroidal epithelium
Fenestrated and provide no barrier
Endothelial wall of the choroidal capillaries
Creates a blood-CSF barrier by tight junctions
Choroidal epithelium
Active transport, ion exchange mechanisms determines flow of molecules (e.g., Na+, K+, Cl-, Mg++, folates) through the
Choroidal epithelium
Small evaginations of arachnoid into sinus
Arachnoid Villae
Large villi are called
Arachnoid granulations
Giant vacuoles engulf
CSF materials
What are the three layers of meninges?
Dura, Arachnoid, and Pia
Made up of two layers, the periosteal and meningeal layers
-Called pachymeninges
Dura
Combined are called leptomeninges
Arachnoid and Pia Matter
Enlarged areas of subarachnoid space
Cisterns
What are the three perimesencephalic cisterns?
Interpeduncular, Quadrigeminal, and Ambient Cisterns
Where is a lumbar puncture performed in
- ) Adults
- ) Children
- ) L3-L4
2. ) L4-L5
When we measure CSF pressure. Normal pressure in the lying position is
Less than 20 cm (200mm) H2O
We want to obtain samples of CSF for which 4 things?
- ) Subarachnoid hemorrhage
- ) Infections like meningitis
- ) Guillain-Barre
- ) MS
Folds of inner dural layer between brain regions
Dural Folds
What are the 4 dural folds?
Falx cerebri, Falx cerebelli, Tentorium cerebelli, and Diaphragm Sellae
Located in between cerebral hemispheres in the longitudinal fissure
Falx cerebri
Located in between the two hemispheres of the cerebellum
Falx cerebelli
Located in between the posterior cerebral hemispheres and the cerebellum
Tantorium cerebelli
The circular fold beneatht he brain that covers the sella turcica
Diaphragm sellae
What are the three compartments formed from the dural folds?
Supratentorial, infratentorial, and posterior fossa
Meningeal irritation is called
Meningismus
Many pain receptors innervate dura, arachnoid, pia and arteries in
Subarachnoid space
Potential space between the dura and the skull
Epidural space
Potential space between the dura and arachnoid
Subdural space
Real space where the major arteries and veins are found
Subarachnoid space
There is an “actual” epidural space around the
Spinal cord
Hematoma between the skull and dura
Epidural hematoma
Hematoma between the dura and arachnoid matter
Subdural hematoma
Results from trauma to the skull. Usually from the middle meningeal artery
Epidural hematoma
15% of epidural hematomas may also be from
Sinuses
Characterized by a “lense shaped” structure on MRI
Epidural hematoma
Patients often exhibit period of lucidity before severe symptoms with an
Epidural hematoma
Due to tearing of bridging veins which often occurs during rapid accelerations
Subdural hematoma
Shows a characteristic crescent-shape on MRI
-symptoms may progress over longer periods of time
Subdural hematoma
Bleeding into the subarachnoid space usually secondary to head trauma
Subarachnoid hemorrhage
Can be from bleeding from an A-V malformation or ruptured aneurysm
Non-traumatic subarachnoid hematoma
Classic presentation is sudden-onset, severe headache (from meningeal irritation)
Subarachnoid hemorrhage
Responsible for 80% of nontraumatic subarachnoid hemorrhages
Cerebral aneurysm
Form when the vessel wall is weakened, and can burst under conditions of increased pressure
Aneurysms
Most aneurysms occur in the “anterior circulation” supplied by the
Internal carotid artery
Subarachnoid hemmorhage can also be diagnosed by the presence of blood in
CSF
Comprises the exiting fibers that will make the Optic Nerve (CN II), retinal artery and vein
Optic disk
The most important sign of increased ICP is
Papilledema
Results when a tumor in temporal lobe causes temporal lobe to herniate through tentorial Notch
Transtentorial and central herniation (Uncal herniation)
When a subdural hematoma causes the cingulate gyrus to herniate below the falx cerebri
Subfalcine herniation
When a cerebellar tumor causes the cerebellum to herniate through the foramen magnum
Tonsillar herniation
“Water in the head”
-Condition characterized by excess CSF
Hydrocephalus
Enlargement of the ventricles seen on neuroimaging with hydrocephalus
Ventriculomegaly
Ventriculomegaly is caused by increased CSF and can lead to damage to
White matter (Like corpus Callosum)
What are the two types of hydrocephalus?
- ) Communicating
2. ) Non-communicating
CSF can move from lateral ventricles to subarachnoid space but can not be drained from subarachnoid space
Comminicating Hydrocephalus
When flow of CSFis obstructed within the ventricular system and CSF can not enter subarachnoid space
Non-communicating (obstructive) Hydrocephalus
Two major signs of hydrocephalus are especially present in the morning. These are
Headache and Vomiting
The most common cause of obstructive hydrocephalus in children
Aqueductal stenosis
A patient presents with headache, mental slowing, papilledema, and difficulty in upward gaze may have
Obstructive hydrocephalus
Another common cause of obstructive hydrocephalus is
Blocked foramen of Magendie and Luschka
Congenital hindbrain anatomic anomoliesassociated with the downward displacement of the cerebellum, brainstem or craniocervicaljunction
Chiari malformations I-IV
Inferior cerebellum (tonsils) herniate through foramen magnum with
Chiari Malformation
Symptoms usually in adults, caused by compression of medulla and upper spinal cord, (2) compression of cerebellum, and (3) disruption of CSF flow through foramen magnum
Chiari malformations
Chiari malformations produce
Hydrocephalus
The most common chiari malformation
Chiari I
Less common and shows significant herniation through the foramen magnum
-usually a comorbidity of meningomyocele
Chiari II
A choroid plexus papilloma that causes the overproduction of CSF is a rare cause of
Communicating Hydrocephalus
Decreased CSF reabsorption due to arachnoid granulation damage or clogging from infection or hemorrhage is another cause of
Communicating Hydrocephalus
A treatment for chronis hydrocephalus where surgeons insert tubes that let the cerebrospinal fluid drain out of the brain into the abdomen, where the body reabsorbs it
Ventriculoperitoneal Shunting
Ventriculoperitoneal shunting prevents
Brain damage
Has the classic triad of symptoms: Gait disturbance, dementia, and urinary incontinence
Normal Pressure hydrocephalus
Shows swollen ventricles with no increased ICP or papilledema. Only in the elderly
Normal pressure hydrocephalus
Usually the first symptom of normal pressure hydrocephalus
Gait disturbance (Magnetic Gait)
Ventriculomegaly secondary to brian tissue loss
- No increase in ICP
- Not pathological
Hydrocephalus Ex Vacuo
