Lecture 5: Meninges, BBB, and CSF Flashcards
What are the meninges?
Dura mater
Arachnoid mater
Pia mater
What is the enhancement the dura mater?
Pachymeninges
What is the enhancement if the arachnoid mater and pia mater?
Leptomeninges
What is the space between the skull and dura mater?
Epidural space (potential space)
What is the epidural space like in the spine?
It is filled with fat
It is an actual space
What is the space between the dura mater and arachnoid mater?
Subdural space (potential space)
What is the space between the arachnoid mater and pia mater?
Subarachnoid space
What is found in the subarachnoid space?
CSF
What are the invaginations of dura in the brain?
Falx Cerebri
Tenorium cerebelli
What does the falx cerebri do?
Separates the two cerebral hemispheres on the dorsal half
Houses dorsal sagittal sinus
What does the tenorium cerebelli do?
Separates the cerebellum from cerebrum
What is the path of CSF?
Lateral ventricle in each cerebral cortex
Interventricular foramen
Third ventricle around interthalamic adhesion
Mesencephalic aqueduct through midbrain
Fourth ventricle between pons/medulla and cerebellum
Lateral apertures to subarachnoid space OR central canal in spinal cord
What does CSF fill?
The ventricles and subarachnoid space
Where is CSF made?
Choroid plexus of lateral and fourth ventricles
What is the choroid plexus?
Highly vascularized area of pia mater invaginate into the ventricle covered by ependymal cells
What creates the blood-CSF barrier?
Tight junction between the choroid ependymal cells
Where is CSF reabsorbed?
Arachnoid villi
What does CSF do?
Reduces effective weigh of brain by floating it
Protects from trauma
Maintains chemical environment for neurons by removing waste and providing micronutrients
Collection and analysis of cell count/type and protein count for diagnostics
Where do you collect CSF for analysis?
Cisternal or lumbar acquisition
What should the CSF look like?
Clear and colorless
What is the cell count of CSF?
Less than 5 total nucleated cell count
Mononuclear
What is the protein count of CSF?
Less than 25 mg/dl cisternal
Less than 45 mg/dl lumbar
What does it mean if the CSF is red tinged?
Xanthochromia
Previous hemorrhage
What is red tinged CSF common with?
Equine herpes 1 myeloencephalopathy
What does a high white count in CSF mean?
Meningitis, inflammation
What does high protein in CSF mean?
Meningitis, tissue damage
What happens to the ventral spinal artery become at the foramen magnum?
Basilar artery
What does the basilar artery give off?
Caudal cerebellar artery and labyrinthine artery
When the basilar artery courses rostrally, what does it branch into?
Right and left to join carotid arteries
What does the arterial blood supply in the dog form?
Arterial circle (Circle of Willis)
What makes up the Circle of Willis?
Rostral cerebral artery
Middle cerebral artery
Caudal cerebral artery
Rostral cerebellar artery
What is the blood supply to the arterial circle in the cat, sheep, and ox?
Maxillary artery to middle meningeal artery and maxillary rete
What does the maxillary artery come from?
External carotid artery
Why do you not want to use a mouth gag in cats under anesthesia?
It can hyperextend the jaw, which could cut off the blood supply from the maxillary artery leading to cortical blindness
Where is the rostral cerebral artery found?
Medial rostral cortex
Where is the middle cerebral artery found?
Lateral cortex, deep white and gray matter
Where is the caudal cerebral artery found?
Medial caudal cortex, midbrain
Where is the rostral cerebellar artery found?
Rostral cerebellum, midbrain
Where is the caudal cerebellar artery found?
Caudal cerebellum
Where is the labyrinthine artery found?
Brainstem
What is in the occipital bone for blood drainage?
Dorsal sagittal sinus and transverse sinus
What mirrors the arterial circle in blood drainage?
Cavernous sinus
What does the cavernous sinus drain into?
Maxillary, vertebral, occipital, and internal jugular veins
What does the blood brain barrier do?
Keeps blood products out of the brain/CSF
What does the blood-brain barrier limit?
Pathogen exposure in the brain
Medication exposure in the brain
What is the composure of BBB?
Tight junctions between capillary endothelial cells
Astrocytes foot processes surrounding capillaries
