Unit 2 Central Nervous System
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Unit 2 Central Nervous System
Unit 2 CNS
(shows lighter on CT)
(shows darker on CT)
three major parts of the brain:
parts of the brain stem
components of forebrain
components of midbrain
stemlike portion that connects the cerebrum to the pons and cerebelum
connects forebrain to hindbrain
components of hindbrain
largest part of the brain.
longitudinal fissures (R&L hemispheres with ventricles)
contains hypothalamus and thalamus.
composed of structures located near midline of the brain
contains pituitary gland (inferiorly) (aka hypophysis cerebri)
largest part of
transverse sulci gives it a sauliflower look.
tissue b/w sulci or fissures of cerebellum
median constricted area the serperates the hemispheres of the cerebellum
seperates the cerebellum from cerebrum
of the cerebrum divides it into right and left hemispheres
connects the cerebral hemisphere.
main nerve fiber of cerebrum.
each cerebrum hemisphere has a
that contain CSF and surrounds the 3rd ventricle
slender, elongated structure.
inner part is a gray cellular substance. (shaped like "H" when cut transversely)
white fibrous substance surrounds the "H"
spinal cord connects to medulla oblongata at the level of
spinal cord extends to the space of the
1st or 2nd lumbar vertebrae
the pointed area where the cord ends
fibrous strand that extends from the conus medullaris and attaches the cord to the upper coccygeal segment
pairs of spinal nerves are transmitted thru the intervertebral and sacral foramina
nerves below the termination of the spinal cord that extend inferiorly thru the vertebral canal
(resembles a horses tail)
lower portion of the dura that extends below the spinal cord to the level of S2 that encloses the cauda equina
protective membranes that cover brain and spinal cord
inner sheath "tender mother"
adheres closely to the underlying brain and cord structure
delicate central sheath
resembles a spider web
hard "tough mother"
fibrous outermost protective sheath of the spinal cord
adheres to bone
two layers of dura:
outer layer of dura
lines the cranial bones serving as periosteum
inner layer of dura
spaces for venous sinuses which are large venous blood vessels
b/w the dura and the vertebral periosteum
b/w dura and arachnoid
b/w arachnoid and pia
filled with CSF
communicates with ventricles
contained in the ventricles of the brain and the subarachnoid space.
water cushion protecting the brain and spinal cord from physical injury.
coats the spinal cord in nutrients.
CSF can increase and decrease with shrinking or expanding of
network of capillaries located in the ventricles
widened areas of the subarachnoid space.
filled with CSF
widest space of the subarachnoid space.
triangular in shape and at the post-sup part of the subarachnoid space b/w the base od the cerebellum and dorsal surface of the medulla oblongata
allow communication fo the subarachnoid space and ventricles
foramen of magendie
foramen of lusckka
bleeding b/w dura and skull
bleeding b/w dura and arachnoid
four partitions of the dura
R & L tentorium
runs through the interhemispheric fissure and provides support for the cerebral hemispherers
seperates the occipital lobe of the cerebrum from the cerebellum
seperates the two cerebelli hemispheres
name the portions of the ventricles:
body- central portion
anterior- frontal horn
posterior- occipital horn
inferior- temporal horn
the 3rd ventricle is
in shape while the 4th ventricle is
the pointed end of the 4th ventricle is continuous with the
central canal of the medulla oblongata
connects each lateral ventricle to the 3rd ventricle
"foramen of monroe"
the 3rd ventricle also communicates with the 4th ventricle through the
cerebral aqueduct of "acqueduct of sylvius"
acqueduct of sylvius
median and lateral aperatures (magendie and lyscka)
remainder of aubarachnoid space
radiographic examination of the CNS structures within the vertebral canal such as spinal chord and nerve root branches
in myelography an intrathecal injection is made and
contrast is put into the
space and the spinal chord and nerve roots are outlined
non ionic water soluble inert (non reactive)
what are the two areas that can be punctured for myelography
L2-L3 or L3-L4 interspace
name 3 non ionic agents used in myelography
how much contrast is used for c-spine myelography?
C&L 9-12 cc's water soluble
T 25-30 cc oil and 12 cc water soluble
contraindications to myelogram
blood in the CSF
increased intracranial pressure
previous lumbar puncture performed within 2 weeks of current
steps to myelogram
explain the details of the exam to the pt
1 hour before exam, sedative is given
pt should be well hydrated
use aseptic technique
the head must be extended while the patient in the trendelenburg position to
prevent contrast from flowing into the ventricles
steps to cervical puncture myelography
pt seated prone with head flexed to place the external occipital protuberence in line with the spinous processes
clean skin with antiseptic
SPINAL NEEDLE INSERTED INTO CISTERNAE MAGNA
when needle is inplace position table to prevent contrast from entering the ventricles
remove needle and extend neck
centering for a cervical myelography
vertical or horizontal ray may be used
center to C5
routine images for lumbar myelography
AP or PA
x table with grid
conus projections for conus medullaris:
AP centered to T12 L1
images followed by CT
explain post myelogram patient care
pt's head and shoulders elevated 30-45 degrees
remain in recovery for 4-8 hours and rest for several hours
plenty of fluids
exam of the puncture site before departure
CT myelography is done to:
done to visualize size, shape, and position of the spinal cord and nerve roots
radiologic examination of individual intervertebral disks
routine for a CT head
gantry angle 20-25 degrees to OML
lowest slice, upper cervical/foramen magnum and the roof of the orbits are seen.