Meninges & CSF Flashcards
Two layers of dura mater
Meningeal and periosteal
Where does periosteal layer end?
Foramen magnum
Where in the brain is CSF?
subarachnoid space
Through what structures does CSF enter venous sinuses?
Arachnoid villi/granulations
What veins cross arachnoid, subdural, and meningeal dura to empty into sinuses?
Subdural bridging veins
Where should you perform a lumbar puncture for adults and children?
Under L3 - adults
Under L4 - children
What is the epidural space used for? What structure do you cross?
Epidural block - anesthesia
Ligamentum flavum
4 functions of CSF
- Buoyancy to brain
- Dampens effects of trauma
- Stable ionic env
- Removes metabolites from brain ECF
What color is normal CSF? Glucose level? Protein level? Cells?
Clear - low protein and glucose, acellular
What structure makes CSF? What type of endothelium does it have?
Choroid plexus - fenestrated, leaky capillary endothelium
What enzyme is needed for CSF production?
Carbonic anhydrase
What cells have cilia to move CSF along?
Ependymal cells
Trace flow of CSF starting from choroid plexus.
Choroid plexus –> lateral ventricles –> foramina of Monro –> third ventricle –> cerebral aqueduct of Sylvisu –> fourth ventricle –> foramina of Luschkas and Magendie –> cisterna magna –> spinal cord and brain –> arachnoid villi –> venous system
Inflammation or infection of meninges
Symptoms?
Meningitis
Headache, fever, neck stiffness, photophobia, encephalopathy
Benign, slow growing, asymptomatic tumor of meninges
Meningioma
Lens-shaped bleed often caused by damage to MMA due to trauma
Crosses cranial sutures?
Epidural bleed
Can’t cross
Crescent-shaped bleed often caused by trauma to bridging veins
Crosses cranial sutures?
Subdural bleed
Can cross sutures, but not midline
Diffuse bleed commonly caused by trauma or aneurysmal rupture
Subarachnoid bleed
Blocked CSF flow
What are the two types?
Hydrocephalus
Non-communicating (obstructive)
Communicating (impaired absorption)
What are symptoms of increased intracranial pressure (ICP)?
Headache, vomiting, Cushing’s reflex, bradycardia, HTN, papilledema
What can cause ICP (increased intracranial pressure)?
Diffuse or focal edema in brain, hydrocephalus, meningitis, bleeds, tumors, abscesses
What does increased protein levels in CSF indicate?
Infection or inflammation (Abs from GBS or MS for example)
What does increased white cells and decreased glucose in CSF indicate?
Infection or inflammation
Neutrophils - bac. meningitis
Lymphocytes - aseptic process
What does increased red cells in CSF indicate?
Subarachnoid hemorrhage, hemorrhagic meningitis (HSV)
