Meningeal CSF Flashcards
What composes the leptomeninges?
Pia + Arachnoid
What are the fibers of the ARACHNOID that extend onto the brain & attack to PIA?
TRABECULAE
What are the 3 meningeal coverings?
- Dura
- Arachnoid (forms the barrrier to not let anything from DURA into cranial cavity)
- PIA
What meningeal layer:
- Provides mechanical strength
- Has no spaces on either side
- contains VENOUS SINUSES
- Has its own blood supply
- Pain sensitive
DURA
What innervates the dura?
Front = TRIGEMINAL N.
Back of Skull = Cervical Nerves (C1, C2)
What part of the dura separates the left & right hemisphere? Which part of the dura houses the Cerebellum?
- Falx Cerebri
2. Tentorium Cerebelli
What is found within the Tentorial Notch?
BRAINSTEM
- how brainstem connects with brain
Where does CSF drain into?Through what structure of the Arachnoid Mater?
- VENOUS sinuses
2. Arachnoid VIlli
How would a skin infection enter through the sinus pathways?
EMISSARY VEINS
What is the first barrier? Second?
Arachnoid
Pia
What suspends the brain?
Arachnoid Trabeculae
Where do cerebral arteries and veins travel?
Where is this space found?
SUBARACHNOID SPACE
- space found between ARACHNOID & Pia and is filled with CSF
What covers the surface of the brain?
PIA MATER
- abuts against astrocyte feet at surface of CNS
Where in the body is the PIA covering thickened? What are these 2 places in this region called?
- SPINAL CORD
2a. Denticulate Ligament
- anchor spinal cord to arachnoid
2b. Filum Terminale
- ancor spinal cord to spinal dural sheath
Where is the inner layer of cranial dura continuous with the spinal dural sheath?
FORAMEN MAGNUM
Where is there an epidural
space? Where does the spinal dura & arachnoid end?
SPINE
- outside vertebral bodies & cranial cavity
- between periosteum & dura
2. END AT L1/L2
What connects the Lateral Ventricles to the 3rd Ventricle? The 3rd ventricle to the 4th?
- Interventricular Foramen (Foramen of Monroe)
2. Cerebral Aqueduct
Where does the 3rd ventricle open? Cerebral Aqueduct? 4th?
- THalamus
- Midbrain
- CEREBELLUM
How does CSF exit the 4th ventricle?
2 Lateral and 1 median Aperture
- Foramen of Luschka
- Foramen of Magendie
What are the 3 places CSF is made? What absorbs it in these locations?
- CHOROID PLEXU (main)
- Capillaries
- Metabolic
ALL absorbed by ARACHNOID VILLA
What is the Blood-CSF barrier? What are the 3 main components?
CHOROID PLEXUS
- Pia
- Capillary - fenestrated*
= vascular** - CHOROID EPITHELIUM
- ependymal cells w/ tight junctions
What type of cells line the ventricles?
EPENDYMAL CELLS (choroid epithelium) w/ TIGHT JUNCTIONS*
- water transported ACTIVELY
What is found outside the pia?
Subarachnoid space
What are the 3 areas Choroid Plexus is made?
- Lateral Ventricle
- 3rd Ventricle
- 4th Ventricle
- requires EPENDYMAL cells to be close to pia
What is the step by step route of CSF? (5 steps)
- made in CHOROID PLEXUS of the VENTRICLES
- exits via Foramen of Luschka + Foramen of Magendie (median & lateral)
- move into CISTERNs
- through TENTORIAL NOTCH
- through ARACHNOID VILLI into Dural VENOUS SINUS
Where does CSF end up? How?
VENOUS SINUSES
- through ARACHNOID VILLI
What 2 areas is the ependyma close to the pia?
Transverse Cerebellar FISSURE
& LATERAL VENTRICLES
What are the 5 main functions of CSF?
- MECHANICAL SUPPORT (buoyancy)
- Buffering system
- COmmunication w/ extracellular fluid
- Sink for substances to be absorbed/reabsorbed
- SPREAD OF
“neuroactive” HORMONES
= a TRANSPORT SYSTEM
What is the pathological state of excessive CSF accumulation in ventricles or subarachnoid spaces?
HYDROCEPHALUS
What is Hydrocephalus usually determined by?
Hydrostatic Pressure
insufficient absorption; classical hypothesis
What are the 2 main circumventricular organs? Which is secretory and which is sensory?
- Area Postrema = SENSORY
2. Neurohypophysis = SECRETORY
What makes Circumventricular Organs unique?
Lack a blood brain barrier
= NO TIGHT JUNCTIONS
(made of neurons, glia, ependymal cells, leptomeningeal, and vascular elements)
What specialized cells overly the ependymal cells in CIRCUMVENTRICULAR organs?
Tanycytes
- barrier between organ & ventricular CSF
What are the common areas of meningeal bleeding/ abnormal spaces?
- Epidural
- Subdural
- Subarachnoid (aneurisms*)
- Intraparenchymal (in brain)
- Intraventricular
What is the term for bleeding within the brain itself?
Intraparenchymal/ Intracerebral
What is brain herniation?
develop a mass inside cavity and squeeze out CSF
- due to tumor, hemorrhage, traumatic brain injury
= INCREASE IN INTRACRANIAL PRESSURE
What are common areas of herniation?
- Transtentorial Hematoma
- Subfalcine (falx pushed by hemisphere)
- Epidural Hematoma (dura pushed away from skull)
Laceration of which artery is the cause for an EPIDURAL HEMATOMA?
Middle Meningeal Artery
