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519 Cards in this Set

  • Front
  • Back
What is the #1 neurological disease?
Stroke
What does the central nervous system consist of?
Brain stem, spinal cord, cerebellum, and diencephalon
What is the primary responsibility of the CNS?
Survival
Where is visual information processed?
Occipital lobe
Where is auditory information processed?
Temporal lobe
Where is cognitive or "personality" information processed?
Frontal lobe
Where is memory information processed?
Temporal lobe
Where is the motor information processed?
Frontal lobe
Where is the major relay station for all sensory information?
Thalamus
What do neurons consist of?
Cell bodies, axons, dendrites
What is the site of action in a neuron?
The dendritic spines
What are sensory neuron?
Afferent
What are motor neurons?
Efferent
What are interneurons?
95% of neurons; integrate sensory and motor; doing all the work
Where are the lower motor neurons?
They leave the brain and spinal cord through peripheal neurons and go to muscles
Where are the upper motor neurons?
They go to the spinal cord
What neurons does Polio virus affect?
Lower motor neurons
What neurons does Lou Gerig's disease affect?
Upper and lower motor neurons
What are the conduit for the information to enter our CNS?
Sensory neurons; afferents
What are the conduit for the output from our CNS?
Motor neurons; efferents
What kinds of neurons does the dorsal root ganglia contain?
Pseudounipolar
What are the two types of interneurons?
Projection and local interneurons
What are glial cells in the CNS?
Astrocytes, oligodendrites, and microglial cells
What do astrocytes do?
Maintain homeostasis; major source of growth factor
What do oligodendrocites do?
Myelination in the CNS; inhibit growth
What do microglial cells do?
Process is unknown
What are the glial cells in the PNS?
Schwann and satellite cells
Where are Schwann cells?
myelinating and unmyelinating
Where are Satellite cells?
next to cell bodies of peripheral sensory neurons
What are the three parts of the brainstem?
Medulla, pons, and midbrain
Rostral end.....
The front of the brain
Caudal end....
the back of the brain
Fasiculis Gracilis....
carrying sensory info from leg; below t6
Fasiculis cuneatus.....
above t6
Gray matter.....
Cell bodies
White matter....
myelinated axons
What are faniculi?
Chunks of white matter
What are roots composed of?
Rootlets
Ventral....
Motor
Dorsal....
Sensory
What does the forebrain consist of?
Telencephalon and Diencephalon
What does the diencephalon contain?
Thalamus and hypothalamus
Where is the 3rd ventricle located?
Diencephalon
Central sulcus also called.....
Rolando
Lateral sulcus also called....
Sylvian fissure
What does the central sulcus separate?
Frontal from parietal lobe
What does the lateral sulcus separate?
Frontal from temporal lobe and parietal from temporal lobe
What does the paracentral lobule consist of?
The precentral and postcentral gyrus
Where is the motor cortex located?
The precentral gyrus
Where is the somatosensory cortex located?
The postcentral gyrus
Where is the calcarine sulcus located?
In the occipital lobe; visual cortex
What is the gyrus called within the limbic lobe?
The singulate gyrus
What does the limbic lobe control?
Emotions and memory
What are the 3 gyri located in the temporal lobe?
Superior, middle and inferior temporal gyrus
What does the inferior temporal gyrus do?
Face recognition
What sits in the superior temporal gyrus?
Auditory cortex
What are the 3 gyri located in the frontal lobe?
Superior, middle, and inferior frontal gyrus
What are the parts of the inferior frontal gyrus?
Pars opercularis, pars triangularis, and pars orbitalis
What special thing is located in the pars opercularis and pars triangularis?
Brocca's area
What does Brocca's area control?
Speech and language
What does the postcentral gyrus map?
The face, arm and trunk
What does the paracentral lobule map?
The legs and feet
What kind of information do the caliculi receive?
Sensory information
What does the superior caliculi receive?
Visual info
What does the inferior caliculi receive?
Auditory info
What area of the brain is cranial nerve II located?
Diencepahlon
What area of the brain is cranial nerve III located?
Midbrain
What is the only cranial nerve that comes off the doral side of the brain?
Trochlear nerve (IV)
Where is cranial nerve XII located?
Between the olive and the pyramid in the medulla
Where do IX, X, XI, and XII exit?
The medulla
Where do V, VI, VII, VIII exit?
Pons
Where are the colliculi located?
Midbrain
What are the peduncles?
Major pathways connecting the cortex, cerebellum, and the brain stem
What is the facial colliculus?
fiber bundles of cranial nerve VII
What do the neural crest cells give rise to?
The majority of the cells in the peripheal nervous system
What are specific examples of things neural crest cells give rise to?
Dorsal root ganglia, sympathetic ganglia, parasympathetic ganglia, adrenal medulla, enteric nervous system
What are the 3 bulges in the neural tube?
Prosencephalon, mesencephalon, and rhombencephalon
What does the prosencephalon give rise to?
Telencephalon and Diencephalon
What does the telencephalon give rise to?
Cerebral hemispheres and basal ganglia
What does the diencephalon give rise to?
Thalamus, Hypothalamus, and Retina
What does the mesencephalon contain?
Midbrain and cerebral aqueduct
What does the rhombencepahlon give rise to?
Metencephalon and Myelencephalon
What does the mesencephalon give rise to?
Cerebellum and Pons
What does the myelencephalon give rise to?
Medulla
Which ventricle forms a diamond shape?
4th ventricle
What happens when the anterior neuropore fails to close?
Anencephaly
What happens when the posterior neuropore fails to close?
Spina bifida
What is the sulcus limitans?
Divides the spinal cord into the dorsal/sensory ALAR plate and the ventral/motor BASAL plate
What does the ALAR plate do?
Sensory
What do the neural crest cells give rise to?
The majority of the cells in the peripheal nervous system
What are specific examples of things neural crest cells give rise to?
Dorsal root ganglia, sympathetic ganglia, parasympathetic ganglia, adrenal medulla, enteric nervous system
What are the 3 bulges in the neural tube?
Prosencephalon, mesencephalon, and rhombencephalon
What does the prosencephalon give rise to?
Telencephalon and Diencephalon
What does the telencephalon give rise to?
Cerebral hemispheres and basal ganglia
What does the diencephalon give rise to?
Thalamus, Hypothalamus, and Retina
What does the mesencephalon contain?
Midbrain and cerebral aqueduct
What does the rhombencepahlon give rise to?
Metencephalon and Myelencephalon
What does the mesencephalon give rise to?
Cerebellum and Pons
What does the myelencephalon give rise to?
Medulla
Which ventricle forms a diamond shape?
4th ventricle
What happens when the anterior neuropore fails to close?
Anencephaly
What happens when the posterior neuropore fails to close?
Spina bifida
What is the sulcus limitans?
Divides the spinal cord into the dorsal/sensory ALAR plate and the ventral/motor BASAL plate
What does the ALAR plate do?
Sensory
What do the neural crest cells give rise to?
The majority of the cells in the peripheal nervous system
What are specific examples of things neural crest cells give rise to?
Dorsal root ganglia, sympathetic ganglia, parasympathetic ganglia, adrenal medulla, enteric nervous system
What are the 3 bulges in the neural tube?
Prosencephalon, mesencephalon, and rhombencephalon
What does the prosencephalon give rise to?
Telencephalon and Diencephalon
What does the telencephalon give rise to?
Cerebral hemispheres and basal ganglia
What does the diencephalon give rise to?
Thalamus, Hypothalamus, and Retina
What does the mesencephalon contain?
Midbrain and cerebral aqueduct
What does the rhombencepahlon give rise to?
Metencephalon and Myelencephalon
What does the mesencephalon give rise to?
Cerebellum and Pons
What does the myelencephalon give rise to?
Medulla
Which ventricle forms a diamond shape?
4th ventricle
What happens when the anterior neuropore fails to close?
Anencephaly
What happens when the posterior neuropore fails to close?
Spina bifida
What is the sulcus limitans?
Divides the spinal cord into the dorsal/sensory ALAR plate and the ventral/motor BASAL plate
What does the ALAR plate do?
Sensory
What does the BASAL plate do?
Motor
Where do lower motor neurons synapse?
On muscle
In the 4th ventricle, what causes the walls to spread apart?
The pontine flexure
What is the result of the pontine flexure?
The dorsal-ventral arrangement of sensory and motor areas become arranged laterally-medially.
In the medulla, which is most medial (motor or sensory)?
Motor is the most medial
In the medulla, which is most lateral (motor or sensory)?
Sensory is the most lateral
How do you tell if a cerebral hemisphere is mature?
If it has gyri it is mature; if it is smooth it is immature
Where are neurons born?
Ventricular zone
How many cell layers extend out from the ventriclar zone?
6
The oldest neuron is located in which cell layer?
6th
When does migration in the cortex peak?
Between the 11th and 15th week of gestation
When do the majority of cells complete migration in the cortex?
By the 24th week
What is a disorder of neuronal proliferation and/or survival?
Microcephaly
What is microcephaly?
Small head; brain doesn't achieve normal size
What is a disorder of neuronal migration?
Lissencephaly
What is lissencephaly?
smooth brain; normal gyrations absent or reduced so brain appears smooth; cortex is thickened and has 4 layers instead of 6
What two arteries supply blood to the brain?
Internal carotid (anterior) and vertebral arteries (posterior)
What do the verterbral arteries join to form?
The basilar artery
The internal carotid and basilar arteries join to form.....
The circle of willis
What artery branches off the verterbral arteries?
The posterior inferior cerebellar artery (PICA)
Where does the anterior inferior cerebellar artery (AICA) branch from?
The basilar artery
What is the next branch off the basilar artery after the AICA?
The superior cerebellar artery
What is the next branch after the superior cerebellar artery?
The posterior cerebral artery
What branch does the posterior cerebral artery give off?
The posterior communicating artery
Where does the vertebral artery join the basilar artery?
The medulla/pons junction
What connects the anterior and posterior circulation?
The posterior communicating artery
What does the anterior cerebral artery supply?
Most of the frontal and parietal lobes and the paracentral lobule
What does the posterior cerebral artery supply?
The posterior regions of the brain; the occipital lobe which includes the visual cortex; supplies the medial and inferior temporal lobe
What supplies the bulk of the lateral surface of the brain?
The middle cerebral artery
What does the middle cerebral exit in order to supply the lateral surface of the brain?
The Sylvian fissure
If you have a stroke in the anterior cerebral artery, what will be affected?
The legs and feet on the contralateral side
If you have an infarct in the middle cerebral artery, what area will be affected?
The face and hands of the contralateral side.
What are the deep arteries branching off the MCA?
The lenticulostriate arteries
What do the lenticulostriate arteries supply?
The basal ganglia and the internal capsule
If you have an infarct in the lenticulostriate arteries, what will be affected?
The internal capsule causing total weakness on the contralateral side
What is the most common artery for stroke of the 3 major cerebral arteries?
The middle cerebral artery
What are the divisions of the MCA?
The superior, inferior, and deep
What will be affected if the infarct occurs at the most proximal part of the MCA?
All 3 divisions would be affected---a stem infarct.
What would be affected if you had an infarct in the left MCA superior division?
Right face and arm weakness (upper motor neuron type) and Broca's aphasia
What would be affected if you had an infarct in the right MCA stem?
Prfound left hemineglect, left hemiplegia, left hemianesthesia
What would be affected if there was an infarct in the ACA?
Contralateral weakness and loss of sensation in the lower extremity because of damage to the paracentral lobule
What would be affected if there was an infarct in the PCA?
Loss of one visual cortex.....a stroke in the left PCA would result in loss of visual information from the right side of each eye's visual field (a right homonymous hemianopia)
What are the regions between the ACA and the MCA and the MCA and the PCA called?
Watersheds
What happens if there is an infarct in the ACA-MCA watershed?
The "Man in a Barrell" syndrome (motor and sensory lost in the trunk region)
What area of the brain does the PICA supply?
The medulla and cerebellum
What area of the brain does the AICA supply?
The pons and cerebellum
What area of the brain does the superior cerebellar artery supply?
The midbrain and cerebellum
What area of the brain does the anterior spinal artery supply?
Parts of the medulla
What are the two major arteries that supply the spinal cord?
The anterior and posterior spinal arteries
What portion of the spinal cord does the anterior spinal artery supply?
2/3
What portion of the spinal cord does the posterior spinal artery supply?
1/3
What is a stoke?
Sudden death of brain cells due to a lack of oxygen
What is the 3rd leading cause of death in the US?
Stoke
What are the two possible forms of stoke?
Hemorrhage (20%) and infarct (80%)
What are small vessels infarcts usually called?
Lacunar infarcts
What are the 5 major signs of stroke?
Numbess or weakness or the face, arm, or leg
Confusion, trouble speaking
Trouble seeing
Trouble walking, loss of balance
Severe headache
What do all of the signs of stroke have in common?
They are all SUDDEN in onset
What can we treat patient's with if the stroke is diagnosed within 3 hours?
TPA
What is the penumbra?
Area surrounding the infarct
Are the cells in the penumbra apoptosing or necrosing?
Apotosing
Is necrosis rapid and passive or prolonged?
Rapid and passive
Does necrosis occur at high levels or low levels of excitotoxicity?
high levels
Does apoptosis occur at high levels or low levels of excitotoxicity?
Low levels
Is necrosis reversible or irreversible?
Irreversible
Is apoptosis reversible or irreversible?
Potentially reversible
What is glutamate excitotoxicity?
Major mechanism causing cell death during ischemia
What is the major excitatory neurotransmitter of the brain?
Glutamate
What glutamate receptor plays the "deadly" role in ischemic condition?
NMDA receptor
What is pyramidal decussation?
Crossing over of neurons
Where does decussation occur?
At the medulla-spinal cord junction
Where do 98% of upper motor neurons synapse?
On interneurons
How does a subarachnoid hemorrhage usually present?
As "the worst headache of my life"
How do patients with a subarachnoid hemorrhage usually present?
Drowsy, confused, nuchal rigidity from blood irritating the meninges
How are hemorrhages usually diagnosed?
CT Scan
Where do Berry aneurysms usually occur?
At bifucation of vessels; anterior communicating, posterior communicating MCA birfucation, and bifurcation of the internal carotid in to MCA and ACA
What do the three meningeal layers in the brain do?
Serve as a protection
What do the meninges include?
Dura, arachnoid, and the pia
What is the dura and what does it include?
It is the hard outermost meninge and includes the falx cerebri and the tentorium cerebelli
What is the falx cerebri?
Divides the cerbral hemispheres
What is the tentorium cerebelli?
Hard tent shaped sheet that covers the cerebellum
What is the arachnoid?
A spider web like layer; CSF percolates over the brain
What is the meningeal layer closet to the brain?
The pia
What causes a subarachnoid hematoma?
A tear in the briding veins
Where is the epidural space?
Between the dura and the skull
Where is the subdural space?
Between the arachnoid and the pia
Where is the subarachnoid space?
Between the arachnoid and the pia
What is significant about the subarachnoid space?
It is filled with CSF and it is where the major blood vessels run in the brain
What are the two major sites for hematoma formation?
The epidural and subdural spaces
What artery is involoved in epidural hematoma?
Middle meningeal artery
What does an epidural hematoma look like on CT scan?
A lens-shaped biconvex hematoma; bleeds fast
What does a subdual hematoma look like on CT scan?
A crescent shape; bleeds slowly
What is an uncal herniation?
When the uncus herniates through the tentorial notch
What is the classic triad of symptoms due to an uncal herniation?
"Blown" pupil due to damage to occulomotor nerve, hempleiga, and coma
What part of the brain are the lateral ventricles located in?
The forebrain; telencephalon
What part of the brain is the 3rd ventricle located in?
The diencephalon
What part of the brain is the cerebral aqeuduct located in?
The mesencephalon or midbrain
What part of the brain is the 4th ventricle located in?
The hind brain
What are the different parts of the lateral ventricles?
Frontal (anterior horn), Body, Temporal (inferior horn), and Occipital (posterior horn)
What connects the lateral ventricles with the third ventricle?
The Foramen of Monro
What connects the 3rd ventricle with the 4th ventrcie?
The cerebral aqueduct
What produced the cerebral spinal fluid?
Choroid plexus
What does the choroid plexus produce?
CSF
What kind of cells line the ventricles?
Ependymal cells
What ions make up the CSF?
Mg, Cl, and K
Is the ionic composition tightly controlled?
Yes to maintain a healthy environment
What happens to glucose levels in the CSF in bacterial meningitis?
Glucose drops because bacteria eat all the glucose
Is the protein elevated or low in bacterial meningitis?
Low protein
What is the pattern of flow of CSF?
Choroid plexus, lateral ventricles, foramen of monro, 3rd ventricle, cerebral aqueduct, 4th ventrcile
Where does CSF drain into?
Arachnoid villi or granulations
Where does CSF pool?
In the cisterns and then flows through the subarachnoid space
Where is a CSF for a lumbar puncture taken from?
Lumbar cistern
How much CSF does the choroid plexus produce per day?
500 ml
How much CSF is in the ventricular system?
140 ml
How much CSF is in the ventricles?
25 ml
Where is the remaining 335 ml of CSF located?
subarachnoid space
What happens if the CSF is not absorbed of flow is obstructed and CSF builds up?
Hydrocephalus
What are the 3 causes of development of hydrocephalus?
Excess production of CSF
Obstruction of flow of CSF
Failure to drain CSF properly
What is the most common cause of build up of CSF in the brain?
Obstruction of flow due to tumors, masses, adhesions, or congential causes
What is communicating hydrocephalus?
Ventricles are working fine but CSF flow is obstructed in the subarachnoid space or not absorbed in the granulations
What is noncommunicating hydrocephalus?
Obstruction of flow of CSF between the ventricles
What is an example of noncommunicating hydrcephalus?
Dandy-Walker Syndrome--the exit foramina for the ventricles were not formed
What is the blood brain barrier?
Barrier around the brain that limits what can enter the brain--minimizes infection
What keeps things from entering the blood brain barrier?
Tight junctions between endotheilial cells just in capillaries of the brain
What forms the blood brain barrier?
Endotheilial cells
What reinforces the blood brain barrier?
Astrocytes form foot processes that surround the tight junctions
Besides the blood brain barrier, what is the other type of barrier seen in the brain?
Between the choroid plexus and the CSF--choroid epithelial cells make tight junctions between themselves so that things need to be actively transported across the barrier
Can the CSF freely penetrate the barriers?
Yes--allows it to bathe the neurons and glia in the brain
Are there astrocytes in the choroid plexus barrier?
No
Where are the regions in which the BBB is interrupted?
Area postrema, pineal gland, and neurohypophysis
Where is the area postrema?
4th ventricle--detects toxins that can cause vomitting
What area is called the Chemotactic trigger zone?
The area postrema
Where is the neurohypophysis?
In the pituitary gland--regulates and releases pituitary hormones
What does the pineal gland do?
Releases melatonin that can regulate circadian rhythms
What sugar will open the BBB?
Mannose
What are neurons that respond directly to sensory stimuli called?
Receptors
At the site of the stimulus, what is the electrical potential induced called?
Receptor potential, local potential, or generator potential
Is the receptor potential an action potential?
No!!!! It is a graded potential
Does the local potential travel retrograde or anterograde?
Retrograde
Will an action potential automatically be producded from a local potential?
No....only if the stimulus is stong enough
Does the terminus contain volrage gated channels or stretch receptors?
Stretch receptors
What info does the CNS receive from the sensory stimulus?
Modality, intensity, duration, and location
What is modality?
Vision, hearing, touch, taste, smell
Where is all sensory information relayed to? What is the one exception?
Thalamus
Olfactory system
What are the four distinct modalities (sensations)?
Touch, proprioception, pain, and thermal
What are the types of somatosensory receptors?
Mechanorecptors, thermoreceptors, nociceptors
What do mechanoreceptors respond to?
Physical deformation--physical contact, blood pressure, stretching of the gut and bladder, pressure on the teeth
What do thermoreceptors respond to?
Temperature
What do nociceptors respond to?
Pain and damage
Is the skin a uniform sensory surface?
No--if we touch the skin with a cold probe we will fill cold only if there is a receptor in the spot of the stimulus
What do free nerve endings sense?
Pain and temperature
What do Pacini's corpuscle sense?
Pressure and touch
What do Ruffini endings respond to?
Physical change-mechanoreceptors
What type of fibers are 1A?
Proprioreceptors; Muscle spindle endings
What type of fibers are 1B?
Gogli tendon organs
What type of fibers are type 2?
Mechanoreceptors--Mesinner's corpuscles, merkel endings, and pacinian corpuscles
What is another name for type 2 fibers?
A Beta
What type of fibers are type 3?
Nocioceptors--sharp pain, cold, touch
What is another name for the 3 fibers?
A delta
What type of fibers are type 4?
Nocioceptors and thermoreceptors--slow pain, itch, heat
Which fibers are the largest in diameter?
Type 1A
Which fibers are myelinated?
All but type 4/C
What is another name for type 4 fibers?
C
Which fibers are non myelintaed?
C fibers; type 4
What is the speed of conduction related to?
The axon's diameter
The larger the diameter....
The faster the conduction
Which nerves are affected in diabetic neuropathy?
Smaller nerves
Which nerves are affected in chemotherapy in cancer patients?
Larger nerves
The amplitude of the generator potential is proportional to....
The intensity of the stimulus
What is the receptive field?
The portion of the skin directly innervated by the receptor terminals
Which has a larger receptive field, the back or the fingertip?
The back
Which is more densely innervated, the back or the fingertip?
The fingertip
The more densely innervated....
The smaller the receptive field
What is the territory innervated by each spinal nerve called?
Dermatome
What do dermatomes do?
Help determine the location of a lesion
What is the concept of two-point discrimination?
In order to feel a stimulus in two different places, the stimulus must be applied in two different receptive fields
What is the size of the cortical area devoted to a particular region proportional to?
The number of inputs from that region
Where does a pain and temperature afferent fiber synapse?
In the spinal cord
The pain and temperature afferent fiber leaving the fingertip going to the spinal cord is what kind of neuron?
1st order neuron
What does the pain and temperature afferent fiber synapse on in the spinal cord?
A projection interneuron
A pain and temperature fiber leaving the spinal cord traveling through the medulla to the thalamus is what order neuron?
2nd order neuron
A pain and temperature fiber leaving the thalamus and traveling to the somatosenosry cortex is what order neuron?
3rd order neuron
Where does a mechanoreceptor afferent fiber first synapse?
In the medulla in the cuneate nucleus
The mechanoreceptor afferent fiber leaving the finger traveling to the medulla is what order neuron?
1st order neuron
Once a mechanoreceptor fiber synapses in the cuneate nucleus, what order neuron does it become?
2nd order neuron
What order neurons cross over to the opposite side of the spinal cord?
2nd order neurons
What do lamina I-VI correspond to?
The dorsal horn
What laminae are important areas for pain and tempertaure processing?
Laminae I and II
What are laminae I and II important for?
Processing pain and temperature information
What is Lissauer's tract?
Where A delta and C fibers enter the spinal cord (pain and temperature fibers)
What is the substantia gelatinosa?
Laminae II--receives afferent information from nonmyelinated and myelinated fibers
What nucleus is located in Laminae III-VI?
Nucleus proprius
What does the nucleus proprius do?
Integrates sensory input with information that descends from the brain
What is Laminae VII?
The intermediate zone
What spinal levels correspond with laminae VII?
T1-L2
What nucleus is located in Laminae VII?
Clark's nucleus
What does Clark's nucleus do?
Relays information about proprioception to the cerebellum
What else besides Clark's nucleus is located in Laminae VII?
The intermediolateral nucleus
What kind of neurons are located in the IML?
Preganglionic sympathetic neurons
Where do the preganglionic sympathetic neurons synapse?
In the sympathetic ganglion
What laminae comprise the ventral horn?
VIII and IX
What do laminae VIII and IX correspond to?
The ventral horn
What does laminae VIII contain?
Interneurons that regulate skeletal muscle contraction
What do laminae IX do?
Innervate skeletal muscle
What can a lesion in laminae IX lead to?
Flaccid paralysis
Where is the phrenic nucleus located?
Laminae IX
Which is more severe, injuring a single spinal nerve or a peripheal nerve?
Peripheal nerve because it is a group of spinal nerves joined together
What section of the spinal cord would we see a brachial enlargement?
C8
What section of the spinal cord would we see a lumbar enlargement?
L5
Does the dorsal column get smaller or larger as we move down the spinal cord?
Smaller
Does the lateral faniculus get smaller or larger as we move down the spinal cord?
SmallerB
In a cross section of a spinal cord below T6, would we see one or two dorsal columns?
Only one dorsal column
In a cross section of a spinal cord above t6, would we see one or two dorsal columns?
Two dorsal columns
What does the posterior dorsal column pathway send to the brain?
Proprioception/mechanorecptors
What fibers are involved in the dorsal column pathway?
AB and IA
What are the two components of the dorsal column?
Fasiculis gracilis and fasiculis cuneatus
Where is the first synapse in the dorsal column pathway?
In the medulla--either in the nucleus gracilis and nucleus cuneatus
Where do 2nd orders neurons decussate in the dorsal column pathway?
In the caudal medulla
When the 2nd order neurons decussate, what are they called?
The internal arcuate fibers
Once they decussate, what are they called?
Medial lemniscus
Are the axons in the medial lemniscus conveying contralateral or ipsilateral signals?
Contralateral
Where do axons in the medial lemniscus synapse?
The VPL of the thalamus
Where do 3rd order neurons in the dorsal column pathway synapse?
In the somatosensory cortex
Are the axons in the caudal medulla ipsilateral or contralateral?
Ipsilateral
Are the axons in the rostral medulla ipsilateral or contralateral?
Contralateral
Where are cell bodies of 1st order neurons in the dorsal column pathway located?
In the DRG
Where are cell bodies of 2nd order neurons in the dorsal column pathway located?
In the nucleus cuneatus or nuclues gracilis
Where are cell bodies of 3rd order neurons in the dorsal column pathway located?
In the VPL of the thalamus
What are the internal arcuate fibers doing?
They are decussating
What does the anterolateral pathway convey?
Pain and temperature to the brain
What is the tract of the ALS that specifically stops in the VPL of the thalamus?
The spinothalamic tract
What is the tract of the ALS that goes to the reticular and limbic systems?
The spinoreticular tract
What is the tract of the ALS that goes to the periaqueductal gray region?
The spinomesencephalic tract
Where do 1st order neurons of the ALS synapse?
In the sympathetic ganglion in the spinal cord
Where do 2nd order neurons of the ALS synapse?
In the VPL of the thalamus
Where do neurons in the ALS decussate?
In the anterior commissure
Where do neurons of the spinoreticular tract synapse?
In the intralaminar and mediodorsal nuclei
Where do fibers from the intralaminar nuclei project?
All over the cortex, including the limbic system, to wake it up
What does the spinoreticular pathway project?
The emotional and arousal aspects of pain
Where do fibers in the spinomesencephalic tract project?
The periaquductal gray region of the midbrain
What does fibers in the spinomesencephalic tract regulate?
Decreasing the sensation of pain
What tract controls what when you step on a sharp tack with your foot?
Your spinothalamic tract enables you to realize that something is sharp on your foot; your spinoreticular tract causes you to feel "ouch"; and your spinomesencephalic tract lead to pain modulation allowing you to think it feels better
What is going on in Brown-Sequard Syndrome?
Ipsilateral weakness and sensation and contralateral loss of pain and temperature
Where do touch and pressure afferents enter the brain?
Pons
Where do touch and pressure afferents synapse?
In the principal sensory nucleus--also called the main sensory trigeminal nucleus
After synpasing in the main sensory trigeminal nucleus, where do toch and pressure neurons go?
They decussate and form the trigeminal lemniscus
Where does the trigeminal lemniscus project its neurons to?
The VPM of the thalamus
After synapsing in the VPM of the thalamus, where do neurons go?
To the lateral side of the somatosensory cortex
Where do pain and temperature afferents synapse?
In the spinal trigeminal nucleus
What does the spinal trigeminal tract run adjacent with?
The spinal trigeminal nucleus
From where to where does the trigeminal pathway run?
Midbrain to C2
After synapsing in the spinal trigeminal nucleus, where do pain and temperature fibers go?
They decussate and asscend to the VPM of the thalamus where they synapse again
After synpasing in the VPM of the thalamus, where do pain and temperature afferents go?
To the lateral somtasensory cortex
What does the principal sensory nucleus mediate?
The tactile information--touch and pressure
What does the spinal trigeminal nucleus mediate?
The pain and temperature information
Where are proprioceptive repsonses mediated?
The trigeminal mesencephalic nucleus
What does the trigeminal mesencephalic nucleus develop from?
Nerual crest cells folding inward instead of outward
Where do senosry neurons from the mesencephalic nucleus go?
Sensory neurons go out through the trigeminal nerve to the mandible muscles to mediate the jaw jerk reflex
Where do touch and pressure afferents enter the brain?
Pons
Where do touch and pressure afferents synapse?
In the principal sensory nucleus--also called the main sensory trigeminal nucleus
After synpasing in the main sensory trigeminal nucleus, where do toch and pressure neurons go?
They decussate and form the trigeminal lemniscus
Where does the trigeminal lemniscus project its neurons to?
The VPM of the thalamus
After synapsing in the VPM of the thalamus, where do neurons go?
To the lateral side of the somatosensory cortex
Where do pain and temperature afferents synapse?
In the spinal trigeminal nucleus
What does the spinal trigeminal tract run adjacent with?
The spinal trigeminal nucleus
From where to where does the trigeminal pathway run?
Midbrain to C2
After synapsing in the spinal trigeminal nucleus, where do pain and temperature fibers go?
They decussate and asscend to the VPM of the thalamus where they synapse again
After synpasing in the VPM of the thalamus, where do pain and temperature afferents go?
To the lateral somtasensory cortex
What does the principal sensory nucleus mediate?
The tactile information--touch and pressure
What does the spinal trigeminal nucleus mediate?
The pain and temperature information
Where are proprioceptive repsonses mediated?
The trigeminal mesencephalic nucleus
What does the trigeminal mesencephalic nucleus develop from?
Nerual crest cells folding inward instead of outward
Where do senosry neurons from the mesencephalic nucleus go?
Sensory neurons go out through the trigeminal nerve to the mandible muscles to mediate the jaw jerk reflex
Where do touch and pressure afferents enter the brain?
Pons
Where do touch and pressure afferents synapse?
In the principal sensory nucleus--also called the main sensory trigeminal nucleus
After synpasing in the main sensory trigeminal nucleus, where do toch and pressure neurons go?
They decussate and form the trigeminal lemniscus
Where does the trigeminal lemniscus project its neurons to?
The VPM of the thalamus
After synapsing in the VPM of the thalamus, where do neurons go?
To the lateral side of the somatosensory cortex
Where do pain and temperature afferents synapse?
In the spinal trigeminal nucleus
What does the spinal trigeminal tract run adjacent with?
The spinal trigeminal nucleus
From where to where does the trigeminal pathway run?
Midbrain to C2
After synapsing in the spinal trigeminal nucleus, where do pain and temperature fibers go?
They decussate and asscend to the VPM of the thalamus where they synapse again
After synpasing in the VPM of the thalamus, where do pain and temperature afferents go?
To the lateral somtasensory cortex
What does the principal sensory nucleus mediate?
The tactile information--touch and pressure
What does the spinal trigeminal nucleus mediate?
The pain and temperature information
Where are proprioceptive repsonses mediated?
The trigeminal mesencephalic nucleus
What does the trigeminal mesencephalic nucleus develop from?
Nerual crest cells folding inward instead of outward
Where do senosry neurons from the mesencephalic nucleus go?
Sensory neurons go out through the trigeminal nerve to the mandible muscles to mediate the jaw jerk reflex
Where do touch and pressure afferents enter the brain?
Pons
Where do touch and pressure afferents synapse?
In the principal sensory nucleus--also called the main sensory trigeminal nucleus
After synpasing in the main sensory trigeminal nucleus, where do toch and pressure neurons go?
They decussate and form the trigeminal lemniscus
Where does the trigeminal lemniscus project its neurons to?
The VPM of the thalamus
After synapsing in the VPM of the thalamus, where do neurons go?
To the lateral side of the somatosensory cortex
Where do pain and temperature afferents synapse?
In the spinal trigeminal nucleus
What does the spinal trigeminal tract run adjacent with?
The spinal trigeminal nucleus
From where to where does the trigeminal pathway run?
Midbrain to C2
After synapsing in the spinal trigeminal nucleus, where do pain and temperature fibers go?
They decussate and asscend to the VPM of the thalamus where they synapse again
After synpasing in the VPM of the thalamus, where do pain and temperature afferents go?
To the lateral somtasensory cortex
What does the principal sensory nucleus mediate?
The tactile information--touch and pressure
What does the spinal trigeminal nucleus mediate?
The pain and temperature information
Where are proprioceptive repsonses mediated?
The trigeminal mesencephalic nucleus
What does the trigeminal mesencephalic nucleus develop from?
Nerual crest cells folding inward instead of outward
Where do senosry neurons from the mesencephalic nucleus go?
Sensory neurons go out through the trigeminal nerve to the mandible muscles to mediate the jaw jerk reflex
Where do motor neurons from the mesencephalic trigeminal nucleus travel to?
Through the trigeminal motor nucleus and goes to synapse on muscle in the mandible
Where are proprioception neurons located for the trigeminal nerve?
In the mesencephalic trigeminal nucleus
What is the order of travel for a touch and pressure neuron in the trigeminal nerve?
Enters pons and synapses in the prinicpal sensory nucleus
Decussate and 2nd order neuron travels as trigeminal lemniscus to the VPM of the thalamus
The 3rd order neuron travels to the lateal somatosensory cortex
What is the order of travel for a pain and temperature neuron in the trigeminal nerve?
Enters through the pons and travels down the spnial trigeminal tract
Synapses in the spinal trigeminal nucleus
Decussates and 2nd order neuron travels up the trigeminal thalamic tract to the VPM of the thalamus
3rd order neuron travels to somtosensory cortex
What is the most common reason for physician visits?
Pain
What does nocioception refer to?
The sensing of painful stimuli
What are the three categories of pain?
Normal/Physiological pain
Inflammatory pain
Neuropathic pain
What is physiological pain?
The normal situation--tissue damage activating a nocioceptor
What is inflammatory pain?
Amplification of a normal response
What is neuropathic pain?
Pain caused by injury processess in nerves and by local inflammation in nerves--diabetic neuropathy
What is the most important synpase in pain?
Nocioceptors activating the dorsal horn which starts the whole cascade
What is released in response to tissue injury?
ATP
Bradykinin
Serotonin
H+
Histamine
Prostaglandins
What does substance P do?
Increases capillary permeability and contributes to inflammation
Does activation of a nocioceptor always produce pain?
No, not necessarily
Can you have nocioceptor activity and pain both?
Yes
Can you have nocioceptor activity without pain?
Yes
Can you have pain in absence of nocioceptor activity?
Yes
In the normal situation, when does pain become painful?
Once it reaches a threshold
What is allodynia?
When a stimulus that is not usually painful is now
What is hyperalgesia?
Pain sensation increased in magnitude
What is the sensation of pain?
The activation of nocioceptors
What is the perception of pain?
What the patient "feels"
What is an example of allodynia?
Moving hairs, brushing or warming the skin are all perceived as painful
What causes hyperalgesia?
Sensitization of nocioceptive endings
What are mechanical nocioceptors?
Activated by stong mechanical stimulation--sharp objects
What are thermal nocioceptors?
Respond to extreme heat or cold
When is pain considered "heat pain?"
Above 45 degrees C
What are polymodal nocioceptors?
Respond to several different stimuli--mechanical, heat, and chemical
Does activation of a nocioceptor always produce pain?
No, not necessarily
Can you have nocioceptor activity and pain both?
Yes
Can you have nocioceptor activity without pain?
Yes
Can you have pain in absence of nocioceptor activity?
Yes
In the normal situation, when does pain become painful?
Once it reaches a threshold
What is allodynia?
When a stimulus that is not usually painful is now
What is hyperalgesia?
Pain sensation increased in magnitude
What is the sensation of pain?
The activation of nocioceptors
What is the perception of pain?
What the patient "feels"
What is an example of allodynia?
Moving hairs, brushing or warming the skin are all perceived as painful
What causes hyperalgesia?
Sensitization of nocioceptive endings
What are mechanical nocioceptors?
Activated by stong mechanical stimulation--sharp objects
What are thermal nocioceptors?
Respond to extreme heat or cold
When is pain considered "heat pain?"
Above 45 degrees C
What are polymodal nocioceptors?
Respond to several different stimuli--mechanical, heat, and chemical
What is referred pain?
Pain that arises from nocioceptors in visceral structures but is felt at different sites
What causes referred pain?
The convergence of visceral cutaneous nocioceptors onto the same dorsal horn and the brain can't distinguish the difference
What is the "Shut the Gate" theory of pain?
After getting an injury, you rub the area which stimulates mechanorecptors; that fires the neuron that inhibts the dorsal horn
What is a monosynaptic reflex?
A synapse consisting of one sensory neuron and one motor neuron
What are reflexes called when they involve several interneurons?
Polysynaptic Reflex
What are reflexes called that involve one sensory neuron and one motor neuron?
Monosynaptic reflex
What is a classic monosynaptic reflex?
Deep tendon reflex
What happens when the knee is tapped on with a reflex hammer?
The muscle is stretched which alerts sensory receptors in the extensor muscle
Once a muscle has been stretched, what happens next?
The Ia afferents synapse directly on the alpha lower motor neurons causing contraction of the muscle that was stretched
Besides synapsing on alpha lower motor neurons, what else do Ia afferents synpase on?
Synapses on interneurons that will inhibit the antagonistic muscle, which is the flexor muscle
What is the advantage of Ia afferents synapsing on inhibitory neurons?
It ensures the flexor (antagonistic) muscle relaxes while the other one contracts
What affect would cutting the dorsal root have on the spinal reflex?
It would abolish it
If there is no response to the knee jerk reflex, is there a sensory or motor problem?
It could be a problem with both
What are the two types of motor neurons in the brain and spinal cord?
Alpha and gamma motor neurons
What do the alpha neurons innervate?
The extrafusal muscle fibers
What muscle fibers actually do the contraction or flexion?
The extrafusal muscle fibers
What do the gamma fibers innervate?
The intrafusal muscle fibers
What is the funtion of the gamma motor neurons?
Regulate the length of the intrafusal muscle fibers
What do Ia afferents tell us about the muscle?
The Ia provides information about the rate of change in the muscle; change in length
What do the II receptors tell us about the muscle?
Provide information that the muscle is actually being stretched; confirmation that it is happening
What muscle do Ia and II synpase directly on?
The homonymous muscle
What keeps the muscle "poised" for action?
The gamma motor neurons
What are Golgi Tendon Organs?
Encapsulated sensory endings located at the junction of tendon and muscle
How are GTOs arranged to muscle fibers?
In series
What are GTOs excited by?
A muscle tensing up or contracting
What do GTOs provide information about?
Muscle force
Can GTOs inhibit motor neurons when the force is too great?
Yes
What is the autogenic inhibition or inverse myotactic reflex?
When muscle force is too great, GTOs activate inhibitory neurons in the spinal cord that will inhibit the contracting muscle
What are the inhibitory neurotransmitters?
Glycine or GABA
What is the flexion reflex?
Allows us to quickly withdraw from a painful stimulus
When is the flexion reflex activated?
When a nocioceptor responds to a painful stimulus
When nocioceptors are stimulated in the flexion reflex what happens
Withdrawal of the limb from the source of pain by exciting the ipsilateral flexor muscles and inhibiting the ipsilateral extensor muscles
What is the cross extension reflex?
When the extensor muscles of the contralateral limb are stimulated to provide support for the ipsilateral side
What is spinal shock?
Reflexes are silent initally and then after recovery become over active
After spinal shock, what happens to the reflexes if the spinal cord is still intact?
Hyperreflexia and abnormal reflexes appear
What is the Babinski sign?
Fanning of the toes--not usually present after 1 year of life
What does a positive Babinski sign tell us?
That the corticospinal tract has been interrupted
If peripheal cell bodies are destroyed, can regrowth occur?
No
Distal to the lesion, peripheal nerves regenerate by what kind of process?
Wallerian degeneration
What is Wallerian degeneration?
As the distal segment degenerates, the myelin sheath surrounding it breaks down and is phagocytosed by infiltrating macrophage
Do Schwann cells survive the breaking down of the myelin sheath?
Yes--they dedifferntiate and become immature Schwann cells
Where do the Schwann cells stay resident?
In the Bands of Bunger
The further away an injury occurs relative to the cell body.....
The more likely it is to regenerate
What does IL-1 stimulate?
Schwann cells and nerve growth factor
What is transneuronal damage?
The loss of pre and post neuronal cells due to the loss of the neuron in between
Why are peripheal nerves able to regenerate?
Schwann cells
Macrophages
Integrins/Fibronectin
ECM
Why do CNS cells not regenerate like PNS?
There is much less ECM, very little fibronectin and laminin, no Schwann cells
What allows CNS axons to regrow?
IN-1 antibody
What does IN-1 do?
Blocks the inhibitory protein in olidgodendrites preventing CNS axons from growing
What happens to the astrocytes after injury to the CNS?
Astrocytes proliferate and increase their expression of chondroitin sulfate proteoglycans
What do chondroitin sulfate proteoglycans do?
Inhibit axon growth
What does chondroitinase do?
Fosters nerve fiber growth by digesting scar tissue
What do olfactory ensheathing cells do?
Promote axon regrowth
What is a condition that is often confused with Parkinson's seen in elderly causing confusion and incontinence?
Normal hydrocephalus
What laminae are the alpha and gamma motor neurons located?
Laminae IX