Flashcards in Lab Section 2 Deck (45):
what structures comprise the basal ganglia?
the caudate, putamen, globus pallidus, substantia nigra and subthalamic nucleus
what 7 structures are part of the limbic system?
anterior cingulate gyrus, orbital and medial prefrontal gyri, ventral parts of the basal ganglia, the hippocampus, the amygdala and parts of the thalamus that project to these regions
where is the choroid plexus located with regard to the lateral ventricles?
located lateral to the ventricles, following the "c" shape around from the anterior horn to the inferior horn
where are the foramina of luschka and megendie located?
leuschka: two foramina located on either side of the widest parts of the fourth ventricle laterally
megendie: one foramen at the tip of the diamond of the fourth ventricle; projecting out under the cerebellum
where does the cerebral aqueduct pass through?
through the midbrain anterior to the colliculi (tectum)
what structure forms the roof of the anterior horn and body of the lateral ventricles?
the corpus callosum
what structure forms the lateral border or "floor" of the anterior horn of the lateral ventricles?
the caudate nucleus
what structure forms a hollow on the ventral medial surface of the inferior horn?
what are the lateral borders of the third ventricle?
the thalamus and hypothalamus (anteriorly)
what produces the hole in the third ventricle?
the interthalamic adhesion (massa intermedia)
where does the posterior horn extend to normally?
the calcarine sulcus
what structures surround the cerebral aqueduct?
posteriorly: tectum of the midbrain
anteriorly: tegmentum of the midbrain
describe the borders of the fourth ventricle.
the cerebellum lies posteriorly to the ventricle (posteriorly) and forms the "roof" while the tegmentum of the pons forms the floor of the ventricle anteriorly
what three specializations characterizes the endothelial cells of the blood brain barrier?
tight junctions between cells, high number of mitochondria and few endocytotic vesicles for intracellular transport
what three ways can entry into the brain be achieved?
diffusion of lipid soluble substances, facilitative and energy dependent transport of certain whater soluble substances and by ion channels
which cells contain reverse pumps to move hydrophobic molecules into the blood?
astroglia (have processes that encase brain capillaries
which whole cells can migrate across a healthy blood brain barrier?
macrophages and lymphocytes
which regions of the CNS do not contain a blood brain barrier?
areas that sense fluctuations in the blood to regulate them
what are three causes of breakdown of the blood brain barrier?
brain tumors, bacterial invasion and ischemia
what is the mechanism of damage to the blood brain barrier in ischemia?
stroke damages the Na/K pumps and causes the cells to fill with water. this results in brain edema and increased intracranial pressure
T or F: CSF steady state is the same as blood plasma
describe the choroid plexus.
specialized capillary network surrounded by cuboidal or columnar epithelium
after the fourth ventricle, where does the CSF go?
some of it travels down the central canal of the spinal cord
the rest exits the foramina of luschka and magendie
where does the CSF flow outside of the ventricles? where does it end up going to?
in the subarachnoid space
ends up in the dural sinuses where the arachnoid villi absorb it
where are common places for blockage to occur in obstructive hydrocephalus?
in the intraventricular foramen, the cerebral aqueduct or at the outlet of the fourth ventricle
what is the pathology of communicating hydrocephalus?
there is no blockage of flow but there is disease in the arachnoid villi and absorption is limited
what is papilledema and what is it caused by?
the retinal vessels are engorged and the optic nerve is dilated
caused by increased intracranial pressure
what are 7 symptoms of increased intracranial pressure?
nausea, vomiting, decreased consciousness, headache, cognitive impairment, impaired vision and sixth nerve palsy
why is the composition of CSF clinically significant?
different cellular components may be indicative of stroke or infection. Differing protein composition could result from blood brain barrier breakdown or immunoglobulins
what are the three types of deep white matter tracts and what do they do?
association (between areas of same hemisphere) commissural (between homologous areas of both hemispheres)
projection (connect areas of cortex to lower areas of neuraxis)
what are the four long association fiber tracts?
the superior longitudinal fasciculus (arcuate fasciculus), inferior longitudinal fasciculus, uncinate fasciculus and the cingulum
what areas are connected by the superior longitudinal fasciculus and where is it located?
located deep to the lateral cortex, connects all of the lobes
notably connects broca's motor speech area, werniche's area and the auditory cortex
where is the inferior longitudinal fasciculus located and what does it connect?
deep to the fusiform gyrus
connects the occipital lobe and temporal lobe
where is the uncinate fasciculus located and what does it connect? what is it hypothesized to be involved with?
runs deep to the limen insulae (anterior border of the insula)
connects the frontal and temporal cortices
involved with memory representation of reward and punishment
where is the cingulum and what does it connect? what is it hypothesized to be involved with?
runs deep to the cingulate gyrus
connects gyri of the limbic system (subcallosal, cingulate, parahippocampal and uncas)
may be involved in learning to avoid painful stimuli
where is the hippocampal commissure located and what does it connect?
located between the splenium of the corpus callosum and the posterior part of the thalamus
where the fornices contact each other--interconnects the two hippocampi
what areas does the posterior commissure connect and what is it involved with?
connects the two sides of the rostral midbrain
involved with the pupillary light reflex and is necessary to mediate upward gaze
what are the projection fibers from the cerebral hemispheres called collectively?
the corona radiata
what is the corona radiata called as it passes medially to the lenticulate nucleus?
the internal capsule
where do many of the projection fibers go from the internal capsule?
to the crus cerebri
what types of fibers are contained within the crus cerebri? where are they located in the internal capsule
corticospinal fibers, corticobulbar fibers and corticopontine fibers
mostly located in the posterior limb
what is the pathway of corticopontine fibers?
they travel from the motor cortex to the pontine nuclei. These then project to the contralateral cerebellar hemisphere
from the striatum, where does information project to?
to the globus pallidus that then sends information to the thalamus that projects to motor areas of the cortex
at what level can you see the hypothalamus on the horizontal sections?
around the anterior commissure