C.S.F. Circulation Flashcards
csf is present in the
brain cavity subarachnoid space and central canal of spinal cord
function of csf
- acts a cushion for cns
- csf creates buoyancy
- csf acts as a reservoir regulates contents of skull
- csf nourishes cns
- removes waste products
- moves hormones around
healthy amount of csf present in the brain at one given time is
130ml
csf pressure is
60-160 mm h2o
csf is measured with a
manometer
which structures are pierced in a lumbar puncture
- skin
- subcutaneous fascia
- ligaments supraspinous
- ligament interspinous
- ligament flavum
- space outside dura matter is epidural space dura matter subdural space arachnid matter
- subarachnoid space containing csf
- pia matter is not pierced XXX
what happens if pia matter is pierced in a lumbar puncture
damage to spinal cord
how much ml can be safely drawn during a lumbar puncture
30 ml
signs of high intracranial pressure
- history of unexplained constant headache if patient wakes up with headache high csf should always be considered
- papilledema - optic nerve at the back of the eye becomes swollen. symptoms can include visual disturbances, headaches, and nausea papilldema
- csf accumulates around optic disk margined blurred don’t do lumbar puncture - projectile vomiting
- git regulating centres of medulla vagus nerve from medulla is disturbed vagus nerve controls motility of git causing projectile vomiting - progressively rising blood pressure and progressively falling pulse rate
- because vagus is stimulated vagus is a cardio inhibitor heart rate is reduced heart rate goes down blood pressure goes up struggles to pump ischaemia develops in cns which triggers immense sympathetic overflow which constricts many vessels in body raising body up ischemic brain is important to save
is optic nerve really a nerve or a tract of cns
optic nerve is technically not a nerve its a cns tract proof is that its covered in meninges and its myelinated by oligodendrocytes and not schwann cells
csf lumbar puncture needle is pushed up towards
navel umbilicus
circulation of csf
- csf circulates from the two lateral ventricles through the foramen of monro (inter ventricular foramen) to the third ventricle
- down the aqueduct of sylvius
- to the fourth ventricle
- and into subarachoiud space via median foramen magendie (most pass through this) but also foramen lusaka on either side of fourth ventricle
spaces form openings in the subarachnoid space an anatomic space in the meninges of the brain the space separates two of the meninges the arachnoid mater and the pia mater and are filled with cerebrospinal fluid
cisterns
how many cisterns are there in the cns and there names
- chiasmatic
- interpenduncular
- pontine
- superior
- cerebellomedullary
inter ventricular foramen
the foramen of monro
how much csf is secreted per min and per day
0.5ml per min and 720 ml per day
increases intracranial pressure
- coughing and crying increases the pressure by decreasing absorption of csf
- compression of internal jugular vein
pressure is highest and lowest on csf when
siting and lateral recumbent
weight if brain in and out of csf
- brain weighs: 1400 g
- but in csf it weighs: 50g
csf collection happens at these two spots
- cisternal puncture : between occipital and atlas cistern magna
- lumbar : subarachnoid space in lumbar region between L3-4
connects lateral ventricle to third ventricle
foramen monro
what is the terminal ventricle
is located at the end of the spine it is a little dilated also a dead end
ventricle that lies between the thalami is the
third ventricle
the ventricle of the telencephalon
the lateral ventricles
the ventricle of the diencephalon
third ventricle
the ventricle of the midbrain aka mesencephalon
cerebral aqueduct
the two expanded ends from the third ventricle and the central cavity make which ventricle
the fourth ventricle
where is the fourth ventricle located
located on the posterior aspect of pons and upper medulla and anterior to cerebellum
tube connecting third and fourth ventricle is called
cerebral aqueduct
the ventricle for pons medulla and cerebellum aka rhombencephalon
fourth ventricle
where is csf formed
within the ventricles by chorid plexuses
all cavities within cns are lined with which type of cells
ependymal cells
glucose ratio from cns to blood is
cns glucose level is 2/3 of the blood
epithelial cells covering choroid plexuses have a specialised pump for
sodium (they actively secret sodium attracting chlorine)
in csf how are sodium and chlorine exchanged
sodium is actively pushed by sodium pumps whilst chloride is passively pushed
transported in reverse from csf to blood is
potassium (naturally low in csf)
foramen between fourth ventricle and the subarachnoid space at the cerebellopontine angle (pontine cistern/ cerebellopontine cistern)
foramen of luschka
foramen located on posterior aspect of the fourth ventricle creates cerebellomedullary cistern
foramen magendie (median foramen median aperture)
drains csf
dural venous sinuses lined with epithelial cells
cavity where the arachnoid extends across between the two temporal lobes it encloses the cerebral peduncles and the structures contained in the interpeduncular fossa, and contains the arterial circle of Willis.
interpeduncular cistern
cavity subarachnoid cistern of the subarachnoid space between the splenium of the corpus callosum and the superior surface of the cerebellum it extends between the layers of the tela choroidea of the third ventricle and contains the great cerebral vein and the pineal gland
superior cistern
is formed as the interpeduncular cistern extends forward across the optic chiasm and onto the upper surface of the corpus callosum
chiasmatic cistern
large area in subarachnoid space between medulla and cerebellum
cistern magna
pressure of csf is at 10-18 cm H20
lateral recumbent position
pressure of csf is at 13 cm H20
lying position
pressure of csf is at 30 cm H20
sitting position
ph of csf
7.28 -7.32
noncommunicating (internal) hydrocephalus
obstruction of any foramen
communicating (external) hydrocephalus
blockage of arachnoid villi
gait instability urinary incontinence dementia symptoms of
normal pressure hydrocephalus
hydrocephalous ex vacuo is due to
brain atrophy
congenital hydrocephalus includes
- aqueduct stenosis narrowing of aqueduct
- brain extends to spinal cord
- dandy walker malformation no cerebellar vermis
tapping on the skull near the junction of the frontal temporal and parietal bones yielding resonant sound
macewan sign a result of hydrocephalus in children
sign hydrocephalus in children
- failure of upward gaze: due to pressure on the tectal plate through the supra pineal recess imitation of upward gaze is of supranuclear origin
- macewen sign
- unsteady gait
- large head: sutures are closed, but chronic increased icp will lead to progressive macrocephaly.
- unilateral or bilateral sixth nerve palsy is secondary to increased icp
ophthalmologic sign in young children resulting from upward-gaze paresis eyes appear driven downward, the sclera may be seen between the upper eyelid and the iris, and part of the lower pupil may be covered by the lower eyelid
setting-sun sign of hydrocephalus
visual impairment seen in adults with hydrocephalus
- Parinaud’s syndrome inability to move the eyes up and down caused by compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF)
drug of choice for hydrocephalus
acetazolamide and frusemide
foramen monro blocked
leads to asymmetrical enlargement
cerebral aqueduct blocked
symmetrical enlargement
symptoms of hydrocephalus ex vacu where the brain shrinks
urinary incontinuence - wet
gait - wobbly
dementia - whacky
queckenstedt sign
pressing on internal jugular vein test
