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122 Cards in this Set

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Is the autonomic nervous system considered to be a part of the CNS or PNS?
PNS
Explain the location of spinal nerves in relation to their corresponding vertebral levels in the upper and lower spinal cord.
Upper spinal cord - levels correspond closely to vertebral levels
Lower spinal cord - levels are higher than vertebral levels
What neuronal contents are found in gray matter?
neuronal somata, dendrites, axonal processes, glial cells
What neuronal contents are found in white matter?
pathways (tracts, fasciculi) containing myelinated axons and glial cells
In the brain where is gray matter located in respects to white matter?
gray matter is located outside (white matter is found deep to gray matter)
In the spinal cord where is gray matter found compared to white matter?
Gray matter is located centrally - gray matter is found deep to white matter
define and give an example of a multipolar neuron
(one axon, multiple dendrites)
interneurons
define and give an example of a bipolar neuron
(one axon, one dendrite)
retinal ganglion cells, olfactory neurons
define and give an example of a pseudounipolar neuron
(one axon)
Dorsal root ganglion
What is the RER of neurons called? More specifically, where is this RER found?
Nissl substance
found in dendrites and NEVER in axons
free ribosomes are very characteristic of neurons. How are they arranged in the neuron?
arranged in polyribosomal rosettes of 5-6 ribosomes forming a central core.
This is a prominent organelle in many types of neurons. It is found in the cell body, dendrites, and within the axons.
SER - occupies the space between the RER
This organelle has Nissl bodies clustered on either side of it. It functions in protein glycosylation / modification
Golgi apparatus
This neuron "part" contains acid phosphatases and is involved with degradation of either internal or phagocytosed materials.
lysosomes. (note: peroxisomes are not very numerous in neurons)
What are lipofuscin granules?
the "wear and tear" pigment: tend to accumulate in the neuronal cytoplasm with age.
Where are mitochondria found in the neuron?
found in all parts of the neuron
neuronal mitochondria are in constant motion: they travel between stacks of ER in "roads" called __________.
plasmastrassen
Cilia - where found in neurons, function?
cilia are sometimes found in neurons. Function ill-defined. (may be vestigal)
Which one (axons or dendrites) appear to taper from the cell body outwards?
dendrites taper (axons stay the same)
Where in the dendrite are most synapses found?
on dendritic spines
dendritic spines are dynamic and can change shape in response to chronic stimulation. Why would they want to do this?
1. To increase surface area for synaptic contact
2. To alter the physioelectrical properties of the dendritic surface.
Dendrites can alter their size and shape in response to chronic stimulation. How do they do this?
By filopodeous outgrowth (dendritic branch will extend)
There are two kinds of axons (classified on how far they project). What are they called, what is the difference and which are myelinated?
1. local circuit neurons - project locally, unmyelinated
2. projection neurons - project across long distances, myelinated
What is the function of the axon hillock?
Site of integration (summation) of all the incoming stimuli to the neuron. This is where the neuron "decides" wether to fire an AP or not.
Which part of the axon does not contain RER or a Golgi apparatus?
The axon cylinder
Define axoplasmic flow - elaborate on the directions of flow.
flow/transport of molecules throughout the axon. Flow can be anterograde (forward/away from cell body) or retrograde (backward/towards cell body)
Fast axonal transport relies on microtubules and their associated motor proteins called ___________.
Kinesins
What would stimulate structural change in an axon?
How is this mediated? (which cell part)
chronic stimulation, learning and memory, response to some forms of injury
mediated via axonal growth cones
Two molecular signals that the filopodia of growth cones look for are?
N-CAM (cell adhesion molecule) &
NGF (neurotrophic agent - neuronal growth factor)
What are the three types of synapses?
1. chemical
2. electrical
3. neuromuscular
chemical synapses release ______, _________ or _______ into the synaptic cleft.
chemical signals
neurotransmitters
neuromodulators
A chemical synapse that releases a neuromodulator acts via which mechanism?
second messenger system response
What exactly is an electrical synapse?
A gap junction that allows direct communication between adjacent cells. (Uses ions, Na+, K+, Ca++)
Of chemical and electrical synapses: which one is unidirectional? Which one is bidirectional?
unidirectional - chemical
bidirectional - electronic
in the neuromuscular junction the neurotransmitter is always _______ and it is always ________ (+) or (-).
acetylcholine
excitatory (+)
neurotransmitter receptors embedded in the postsynaptic membrane are usually what type of receptor/channel?
usually chemically - gated ion channels
Which is more abundant in the CNS - neurons or glial cells?
glial cells (~10 times more)
Are astrocytes and oligodendrocytes classified as microglia or macroglia?
macroglia
Where are protoplasmic astrocytes located?
In the gray matter of the CNS
Where are fibrous astrocytes located?
In the white matter
The functions of astrocytes are many. If summarized, what would you say they are?
Support cells for the neurons
What is the glia limitans and what makes it up?
glia limitans - shields CNS from overlying pia mater and CSF; made from the cell bodies or end feet of astrocytes
How do astrocytes contribute to the Blood-Brain-Barrier?
by forming a wall of end feet that surrounds the parenchymal side of capillary endothelium
Which one (oligodendrocytes or Schwann cells) can individually provide myelin for many different axons?
Oligodendrocytes (Schwann cells can only provide myelin for one axon)
Where are interfascicular oligodendrocytes found?
inbetween nerve fibers in the white matter
Are oligodendrocytes found in gray matter? If so, where are they found?
Yes. They are found associating with nerve fibers or forming satellite cells that associate with the neuronal perikaryon
Oligodendrocytes are found in the ____; Schwann cells are found in the _____.
O's -> CNS
S -> PNS
What is the scoop on microglia?
microglia are normally quiescent, but on occasion they can mediate neuro-immune interactions by becoming phagocytically active and demonstrating antigen presentation.
What will activate microglia?
cerebral trauma, ischemia, seizure activity, infection
Where are ependymal cells found and what is their function?
line the ventricles and central canal of spinal cord.
function - cilia produce current for directional flow of CSF.
What makes up the dura mater?
a heavy connective tissue sheet covered by a thin layer of sinple squamous epithelium.
What is the name of the space between the dura and the arachnoid?
The subdural space
How many choroid plexi do we have and where are they?
Four. One in the medial wall of each lateral ventricle; one in the third and one in the fourth ventricles.
Function of choroid plexus?
make CSF from plasma
Total volume of CSF made in the average human per day?
~400 mL
What are the ventricles embryologically derived from?
the lumen of the neural tube
What structure connects the lateral ventricles with the third ventricle?
THe foramen of Monro (interventricular foramen)
What structure connects the IIIrd ventricle with the IVth?
The cerebral aqueduct (of Sylvius)
How does the CSF exit into the subarachnoid space?
via the IVth ventricle foramina: lateral (2) - Foramen of Luschka and medial - Foramen of Magendie
Where is the vasculature that supplies the dura found?
in the subarachnoid space
What is the name of the structures that anchor the arachnoid menix to the pia mater?
arachnoid trabeculae
Which CSF cistern is used clinically to tap for CSF and at what part of the body is it at?
The Lumbar Cistern
Vertebral levels L4-5
(the spinal cord ends at L1-2)
The choroid plexus secretes about 80% of CSF. Where does the other 20% come from?
metabolic water (12%) and secretions by the ependyma of ventricles (8%)
What types of molecules are transported through the blood brain barrier?
ions and proteins
How much CSF (on average) is found in the CNS?
140 mL
What is the relationship of glucose in the CSF vs. the plasma?
CSF glucose is ~66% of plasma glucose
Is there a Na+/K+/ATPase that maintains CSF concentrations?
Yes - this pump is essential for maintaining ion concentrations in the CSF
Compare protein levels in the CSF vs. the plasma. What are the contents of CSF protein?
CSF protein is LOW compared to plasma protein.
CSF protein is mainly albumin (80%) with some gamma globulins (5-10%)
Are there red or white blood cells found in CSF?
should be no RBCs
A few WBCs are normal (0-5/mL)
High RBC levels in the CSF could indicate __________?
High WBC levels in the CSF could indicate _________?
RBCs-subarachnoid hemorrhage
WBCs-infection
Describe the circulation of CSF
from ventricles (out the 3 foramina of the IVth ventricle) into the subarachnoid space - To superior sagittal sinus and it's lacunae - enters venous circulation
What causes a movement of CSF throughout the CNS?
Pressure differences cause CSF mvmnt. (venous circulation has low pressure, SAS has higher pressure, choroid plexus has an even higher pressure)
Which type of hydrocephalus leads to increased intracranial pressure? What, in general, causes it?
communicating hydrocephalus. Caused by
increased CSF production and normal reabsorption OR normal CSF production and decreased reabsorption
Noncommunicating hydrocephalus results from blocked CSF flow. what structures could be blocked to produce this?
foramen of Monro, Luschka, cerebral aqueduct or decreased reabsorption across the arachnoid villi.
Do axons of somatic motor neurons contain synapses in the PNS?
NO. somatic motor neurons synapse in the ventral horn.
Do axons of visceral motor neurons contain synapses in the PNS?
YES. visceral motor neurons synapse, often in the sympathetic ganglion
Preganglionic sympathetics arise from what spinal cord levels?
T1-L2
Preganglionic parasympathetics arise from what spinal cord levels?
S2-4
Where do dorsal and ventral roots join to form spinal nerves?
at the intervertebral foramen
How many vertebrae?
How many pairs of spinal nerves?
33 vertebrae
31 pairs of spinal nerves
Where does C1 spinal nerve exit? What about C8?
C1 exits ABOVE the C1 vertebra pedicle
C8 exits BELOW the C7 vertebra pedicle
What is different about the C1 spinal nerve compared to the other spinal nerves?
C1 is somatic motor only. There is no DRG or dorsal root.
Where do spinal cord levels exit after C7?
Starting with spinal nerve C8, the nerves (and all spinal nerves below C8) exit below the corresponding vertebral pedicle.
What do dorsal rami innervate?
dorsal rami innervate the deep back muscles and the skin of the back of the head.
Ventral rami may have up to 3 branches:
1. Gray communicating ramus ________.
2. White communicating ramus ______.
3. Ventral ramus ________.
1. Grey communicating ramus is found in all spinal nerves
2. White comm. ramus is found from T1-L2 only.
3. Ventral ramus is a continuation to the periphery
Peripheral nerves are referred to as motor, sensory or mixed. However, what do ALL peripheral nerves have?
ALL peripheral nerves carry visceral (sympathetic) efferents and afferents.
What are the 4 cranial nerves that have autonomic components? (parasympathetic preganglionic)
CN III oculomotor
CN VII facial
CN IX glossopharyngeal
CN X vagus
Cranial nerves that are SVE provide motor innervation to which muscles?
SVE - special VISCERAL effer.
to skeletal muscles of pharyngeal arch derivation (larynx, pharynx, face, mastication)
Which CNs are SSA?
CN II - sight
CN VIII -hearing, equilibrium
Which CNs are SVA?
CN IX, VII - taste
Cn I - smell
Important cervical dermatomes:
C2
C6, C7, C8 (respectively)
C2 - EOP
C6 - thumb, C7 - middle finger, C8 - little finger
What are the six internal bones of the skull?
ethmoid, inferior nasal concha, palatine, vomer, lacrimal, ossicles
Which bone makes up a portion of both the cranial vault and the internal bones?
The ethmoid bone
When the skull cap, brain and meninges are removed the cranial fossa are exposed. What are the three cranial fossae?
anterior
middle
posterior
The foramen cecum is found in the _________ cranial fossa. What structure passes through it?
* anterior cranial fossa
* The emissary vein passes through it
Through which foramina do the posterior and anterior ethmoidal nerves and vessels pass?
anterior and posterior ethmoidal foramina
Through which foramen do the olfactory nerves (CN I) pass through?
The cribiform plate
The optic canal has what structures pass through it?
optic nerve (CN II)
Opthalminc artery
Which structures pass through the superior orbital fissure?
CNs III (oculomotor), IV (trochlear), VI (abducens), branches of V1 (opthalmic of trigeminal - frontal, nasociliary, lacrimal), superior opthalmic vein
V2, the maxillary division of the trigeminal nv. passes through which foramen?
foramen rotundum
The foramen ovale has what structures pass through it?
V3 (mandibular division of trigeminal)
What passes through the foramen spinosum?
middle meningeal artery
which foramen do the internal carotid artery and carotid nerve plexus pass through?
the carotid canal
The lesser petrosal nerve is a branch of __________.
The greater petrosal nerve is a branch of _________.
lesser petrosal -> branch of CN IX (glossopharyngeal)
greater petrosal -> branch of CN VII (facial)
what structures pass through the internal acoustic meatus?
CN VII (facial)
CN VIII (vestibulocochlear)
labrynthine artery
what structures pass through the jugular foramem?
CN IX (glossopharyngeal)
CN X (vagus)
CN XI (spinal accessory)
inferior petrosal sinus
sigmoid sinus
posterior meningeal artery
What are the two layers of the dura mater?
1. endosteal layer (bound by Sharpey's fibers to cranium)
2. menigeal layer
From what does the dura mater recieve its sensory innervation?
mainly V1, V2, V3
also CNs X and XI
what is the name of the major blood vessel that supplies the dura mater?
middle meningeal vessels
A rupture in the middle meningeal vessels will result in a ___________ hematoma.
extradural hematoma
where is the falx cerebri found?
the falx cerebri is found inbetween the cerebral hemispheres.
a rupture in the superior cervical vein would cause what type of hemorrhage?
subdural hemorrhage
a cerebral aneurism would cause what type of hemorrhage?
subarachnoid hemorrhage
the common carotid artery is a branch of the _________ artery.
brachiocephalic
Which carotid has no branches in the neck?
the internal carotid
the vertebral arteries are branches off of the ____________ artery?
subclavian
which artery of the head and neck has lots of "bends" and therefore is susceptible to emboli lodging in these bends?
the internal carotid
(bends appear as it passes through the cavernous sinus)
name the 6 arteries that contribute to the cerebral arterior circle
1. internal carotid
2. PCA 3. MCA 4. ACA
5. Ant. comm. artery
6. Post. comm. artery
the opthalmic artery is a branch of which artery?
the internal carotid
T/F: the retina has arteries.
FALSE: the retina is avascular
there are anastomotic connections between the internal and external carotids. Describe 3 of them.
1. dorsal nasal (from IC to opthalmic) and angular (from EC to facial)
2. dorsal nasal to infraorbital (EC to maxillary)
3. supraorbital (IC) and frontal (EC)
What is the common drainage point for the following veins: supraorbital, supratrochlear, dorsal nasal, pterygoid plexus, emissary, opthalmic. Clinical significance?
The canvernous sinus is the common drainage point. Bacteria that enter the cavernous sinus have easy access to the CSF -> result is meningitis