Flashcards in neuroanatomy- gross Deck (214):
what components comprise the central nervous system (CNS)
the brain and the spinal cord are the 2 components that make up the CNS
what components make up the peripheral nervous system (PNS)
the spinan nerves and the cranial nerves make up the PNS
what are 2 ways to classify the nervous system?
the nervous system can be classified anatomically and physiologically
anatomically: CNS and PNS
physiologically:the somatic (voluntary) and autonomic (automatic) nervous systems
which physiological division of the nervous system is responds to the external environment?
the somatic nervous system responds to the external environment, and is comprised of conscious sensation (afferent) as well as striated muscle (efferent)
true or false: the autonomic nervous system regulates the internal environment of the body?
true - the autonomic system regulates the internal environment of the body. the ANS includes sensation as well as control of smooth muscles and glands
what is striated muscle and is it under voluntary or involuntary control?
striated muscle is skeletal muscle and is under voluntary control of the somatic nervous system
T/F: dorsal is synonymous with inferior
FAlse. dorsal is synonymous with Posterior, while inferior is synonymous with caudal (towards the tail)
what is another word for superior?
rostral is another word for superior (rostral = towards the nose/head)
T/F ventral and anterior are synonymous?
True. ventral is synonymous to anterior.
what are the 2 axis of the brain and how are they oriented
there are 2 axis of the brain- the neuraxis that is in line with the brain stem/spinal cord as well as the horizontal neuraxis that bends 80^ (due to cephalic flexure of the embryo- part of humans standing on 2 feet)
there are 2 cross sections possible as a result :
the perpendicular to the neuraxis is a cross section, which the perpendicular to the horizontal neuraxis is the Coronal section
what are the 3 divisions of the brain (embryo)
prosencephalon, mesencephalon, and rhombencephalon
what does the prosencephalon form?
the prosencephlaon develops into the telencephalon that forms the cerebrum, and the diencephalon that forms bt the cerebral hemispheres
what are the -cephalon components of the prosencephalon?
the prosencephalon is made up of the telencephalon (which form the cerebral hemispheres) as well as the diencephalon (whcih literally means middle brain and is nesteld bt the cerebral hemispheres)
what embryological structure is the midbrain?
the midbrain started as the mesencephalon
what structures does the mesencephalon develop into?
the mesecephalon develops into the midbrain
what are the embryological components of the rhombencephalon?
the rhombencephalon is made up of the metecephlaon as well as the myelencephalon
what adult structures form in the rhombencephalon?
the rhombencephalon forms the metencephalon and myelencephalon
t-he metencephalon forms the Pons and the cerebellum ((the pons is the bridge, looks like it has arches))
- the myelencephalon forms the medulla oblongata
what is the ventricular system?
the ventricular system is a seriies of strutures found within the brain that is continuous with the centra canal of the spinal cord. the ventricular system hold the CSF (cerebralspinal fluid) that has the role of support and protection of the brain. te ventricular system houses choroid plexuses which produces mroe CSF
in what division of the brain are the lateral ventricles?
the lateral ventricles are found the the telencephalon (the cerebral hemispheres) - which is a division of the prosencephlaon
what part of the ventricular system is housed by the diencephalon?
the diencephlaon ( a part of the prosencephlon) contains the 3rd vetricle and also contains a choroid plexus. the pathway is from the lateral ventricles, to the 3rd ventricle via the foramen monroa (aka the interventricular aqueduct)and then out to the 4th ventrical via the cerebral aqueduct
what division of the brain houses the cerebral aqueduct?
the cerebral aqueduct is found the mesencephalon (the midbrain) and is the passageway of hte ventriclar system from the 3rd ventricle (of the diencephlaon) to the 4th ventricle (in the rhombencephalon)
where is the 4th ventricle? and what comes after it?
the 4th ventricle is found in the rhombencephalon
- the median and lateral apertures follow the 4th ventricle and lead from the 4th ventricle into th subarachnoid space// also the central canal is after the 4th ventricle and leads down the length of the spinal cord (whcih is much shorter than the spinal column)
T/F astrocytes, oligodendroglia, and microglia are all 3 types of glia cells and are only found in the CNS?
True. astrocytes, oligodendroglia and microglia are the 3 tyes of glia found in the CNS.
- Schwann cells are glia found in the PNS (and have the same role as oligodendroglia.. but carry out the function differently)
T/F - the peripheral nerves comprise the cranial and spinal nerves
True. the peripheral nerves comprise the cranial and spinal nerves linking the CNS to the peripheral tissues.
T/F the spinal nerves are mixed nerves
True. the spinal nerves are mixed nerves that carry both afferent and efferent nerve fibers. the afferent fibers are the posterior nerve roots and the efferent fibers are the anterior nerve roots
T/F the posterior root ganglion is found on each posterior root?
True. the posterior root ganglion-- seen as a swelling-- is found on every posterior root.
Through what vertebral formation does the spinal nerve travel through?
The spinal nerve travels through the intervertebral foramen, and after exiting the spinal cord splits into anterior and posterior rami (that are each MIXED nerves)
what do the posterior rami innervate?
the posterior rami fibers innervate the back (the erector spinae muscles ) and the skin of the trunk
what do the anterior rami fibers innervate?
the anterior rami fibers innervate the the muscles and skin of limbs, the muscels and skin of the side and front of trunk, as well as sensory fibers to the parietal pluera (tissue of the chest inner organs) and parietal peritoneum (the outer covering of organs in the trunk)
what kind of neurons are found in motor neurons? where are they found in the spinal cord
motor (efferent) neurons are either alpha (fast/ reflex/ contraction) neurons or gamma neurons (muscle tone/ procioception). In the spinal cord, the cell bodies of these motor neurons are found in the anterior horn (the area for efferent fibers) of the grey matter. -- the are MULTIPOLAR neurons (only 1 axon 1+ dendrites
what kind of neurons give rise to the posterior nerve roots? - where are these located? - what is their function?
* recall distinction bt nerve roots and nerve rootlets
UNIPOLAR neurons whose cell bodeis are located int eh posterior horn of hte gray matter give rise to the posterior nerve roots. the fibers have a sensory (afferent) function
nerve roots afferent + efferent = spinal nerve (mixed) splits into spinal rami/ rootlets..
do dendrites take information to or away from the cell body? and are they myelinated? how many dendrites does a neuron have?
dendrites take information TO the cell body and are NOT myelinated. A neuron can have 0++ dendrites (0 or multiple)
what is the role of the axon? is it myelinated? how many axons does a neuron have?
the role of the axon is to take information AWAY from the neruonal cell body. axons are (usually) myelinated. each neuron only ever has 1 axon. ever.
what is a fascicle?
a fascicle is a bundle of (nerve) fibers
what is epineurium?
epineurium is vascular CT sheat that surrounds fascicles making up a nerve
what are the symptoms of lower motor neuron lesion?
symptoms of a lower motor lesion include flaccid paralysis, atonia, areflexia, and fasicculations
which of the 4 functional components of the peripheral nerves has a pre-and post ganglionic neuron relay?
the Visceral Efferent (VE) is the functional component of peripheral nerves that has a pre and post ganglionic neurons
T/F Big axons conduct pain signals slower than small axons
False. Big axons carry pain signals faster than slow axons
What are the 2 types of pain? Please give an example.
There is fast pain and slow pain. Ex - slamming hand in drawer -- immediate sensation is fast pain, then the later realized overwhelming and lingering pain is slow pain
Allodynia is a condition where a sensation that is normally not offensive is felt as painful
how many neurons are there in the general sensory pathway?
the general sensory afferent pathwyay GSA has 3 neurons, primary, secondary, teritary
How many dermatomes does one spinal nerve serve?
A spinal nerve serves 3 dermatomes
what is Rexed's lamina 2 called, and what is in involved in?
Rexed's Lamina 2 is aka substantia gelatinosa, and is involved in pain modulation (can suppress pain)
Is the primary motor cortex anterior or posterior to the central sulcus?
The primary motor cortex is anterior to the central sulcus and is aka the precentral primary motor cortex
Where is the primary somatosensory cortex located?
The primary somatosensory cortex, aka the postcentral gyrus, is located in the parietal lobe just posterior to the central sulcus.
How is the homunculus organized (such as, hwere are the feet)
the homunculus looks like a person doubled over a table, The feet are in the medial aspet of the sulcus followed by the upper limb, HAND, face LIPS, tongue/pharynx (the tongue pahrynx area are at the inferior lateral border of the brain along the inferior border of the temporal lobe)
In what lamina does fast pain terminate?
Fast pain terminates in Lamina 1
In what lamina does slow pain terminate?
Slow pain terminates in laminas 2 and 5
What kind of nerve fiber carries crude touch sensation
The A-delta nerve fibers carry crude touch sensation
What kind of sensation(s) does the A-delta fiber carry?
The A-delta nerve fiber carries fast pain, temperature, crude touch
what are the 2 fibers that carry pain? describe
the two fibers that carry pain sensation are the fast-conducting a-delta fibers (ex/ a pinch) A-delta is myelinated and the slow conducting c-fibers (high heat, chemical burn) C fibers are Unmyelinated
which type of pain fibers gives a precise location signal of pain origination -- and which does not?
the a-delta fiber carries pain signals and gives a precise location of pain origination. C-fibers are slow conducting and do not provide precise location of pain source.. instead a nagging pain feel generally located.
what sensations do free nerve endings conduct?
free nerve endings conducts feelings of pain, crude touch, and temperature
what ohysiological functional component are posterior root ganglions associated iwth?
the posterior root ganglions are associated with the afferent nervous system that brings in sensory information to the posterior horn of gray matter in the spinal cord
what kinds of nerves are encapsulated
- what are their functions?
- what kind of fibers are present?
-Meissner corpuslces are encapsulated, a-beta fast conducting fibers.. Meissner corpuscles detect discriminitive touch, such as texture (like braille, or finding a particular coin in your pocket) .
- pacinian corpuslces are also encapsulated, a-beta fast conducting fibers and detect vibration.
=both of these are found abundantly in the fingers and palm.
Are merkel nerve ending encapsulated?
what kind of fiber is a Merkel nerve ending?
what sensation do they detect?
Merkel nerve endings are NOT encapuslated, A-beta fast conducting fibers Merkel nerve endings detect discrimintive touch - like the sustained pressure of wearing eyeglases
what kind of nerve fibers covered are fast conducting?
- where are these fibers found?
A-alpha, a-beta, and a-delta fibers are fast conducting fibers.,
-A-alpha is found int he neuromuscular spindle and detects stretch
-A-beta is found in Meissner corpuscle (discriminitive touch) and Pacinian corpuslve (vibration)
-A-delta is a fast-cindicting pain receptor fiber that specifically locates pain source-- like a hard pinch
What kind of encapsulated nerve fiber looks like an onion? What is the function of this fiber?
The nerve fiber that looks like an onion i the pacinian corpuscle that is a fast-condicting a-beta fiber that deects vibration
what are the three phases of the axon reflex? describe each
the 3 pahses are 1. scratch/ red line 2. flare 3. wheal
1. scratch - a red line appears as the capillaries dilate in response to the impacto f a sharp scratch
2. flare - the red spreads as the arterioles dilate
3. wheal- the area becomes puffy and white as plasma leaks out of the capillaries
pain is carried by c-fibers in the axon relfex. substance P is invloved in stimulating the flare and wheal response
what kind of fiber carries the pain signal from an axon reflex
C-fibers carry the pain signal from an axon reflex.
C-fibers are unmyelinated
what chemical signal is part of hte axon reflex that stimulates the flare and wheal in cells surrounding the source of pain?
Substance P + glutamate, a biosignal that communicates pain, binds to receptors of neighboring cells to promote dialtion of arteriorles (flare) and the release of histamine from mast cells (promoes inflammation and the release of plasma from leaky capillaries) in the wheal stage.
is the orthodromic direction of pain tranmission to or away from the CNS?
orthodromic pain tranmission is where the pain signal travels towards the spinal cord, the CNS
T/F The antidromic direction of pain stimulates neighboring cells to the axon-reflex stimulus source to release substnace P which in turn stimulates the flare and wheal stages.
True. The antdromic direction of pain signals travels Not to the CNS, but to the neighboring nociceptive endings that release Substnace P+ glutamate (pain peptide) in resposne that promotes the flare (capillary dialtion) and wheal (histamine release from mast cells -inflamm, and plasma leasage) stages
T/F encapsulated endings of nerve fibers are mechanoreceptors? give 2 examples
True. the encapsulated endings of nerve fibers are mechanoreceptors -- this includes Meissner corpuscle (discriminitve touch, a-beta, fast conducting, texture)
and pacinian corpuscle (vibration, a-beta fast conducting)
in what levels of the brain cross section is the medial leminiscus visible?
the medial leminiscus is visible in (from inferior to superior) the medulla, the pons, and the midbrain ((all 3 components of the brainstem)
from inferior (connecting to spinal cord) to superior, name the three components to the brain stem
from inferior to superior, the 3 components of the brainstem are the medulla (connects to the spinal cord) the pons ('the bridge') and the midbrain
where is the primary somatosensory cortex located? significance of this cortex?
the primary somatosensory cortex is located in the parietal lobe in the postcentral gyrus. this is the primary receptor for sensory input - touch- and organizes the body via homunculus
what is another name for the postcentral gyrus (fucntional) ?
another name for the post central gyrus is the primary somatosensory cortex. it is the primary center for sensory input and is organized via the homunculus representation of the body
where do both the discriminitive touch pathway and the fast pain pathway ultimately ascend and terminate in?
both the discriminite touch pathway and the fast pain pathway ascend and terminate in the postcentral gyrus - aka the primary somatosensory cortex
T/F anterolateral system is the name for the ascending pathway for both discriminitive touch and slow pain
False. the anterolateral system is an ascending pathway that conveys pain- both the fast pain == the spinothalamic pahtway (( fast = neospinothalamic--carried by a-delta fibers//
slow = paleospinothalamic via c-fibers. . it conveys crude touch, temperature, slow pain.
what kind of pain is emotionally significant (will wake people up in the night, clinically significant)
Slow pain, via c-fibers (the paleospinothalamic tract) is considered to be the emotionally significant type of pain. lingers.
T/F the PAG, periaquetal grey is involved in pain activation
False. the periaqueductal grey is involved inpain suppression
T/F the periaqueductal grey (PAG) is involved in discriminitive touch?
False. The periaqueductal grey is involved in pain suppression
where is the periaqueductal grey located?
- in what pathway is it involved?
The periaqueductal grey in located in the midbrain (along the midline) and is involved in the paleospinothalamic pathway for slow pain tranmission via cfibers (clinically significant pain)
what pathway is substnatia gelatinosa involved in? where is it located?
the substantia gelatinosa is located in lamina II of the posterior horn of hte spinal cord and is involved in the spinothalamic tract (for pain)- and is involved in fast pain (a-delta fibers, via neospinothalamic tract) and slow pain via c-fibers , paleospinothalamic tract
what is the origin and termination of the anterolateral system?
the anterolateral system carries pain (the 2 division of the spinothalamic tract). 'spinothalamic' tells us the origin and temrination of the signal:
origin = spinal cord
what do alpha motor neurons supply?
alpha motor neurons are the largest neurons and supply muscles
what do gamma motor neurons supply?
gamma motor neurons are small and supply muscle spindles
where is the posterior root ganglia found?
the posterior root ganglia is located in the intervertebral foramina
where are concisous sensations perceived?
conscious perceptions are perceived in the cerebral cortex whereas nonconscious perceptions are not
what are the names of the 2 somatic sensory pathways (ascending)?
the 2 ascending smatic sensory pathways are the posterior column-medial lemniscal pathway (discriminitive touch) and the spinothalamic (anterlolateral ) pathway (for fast and slow pain)
how many orders of neurons are present in each of the 2 somatic sensory (ascending) pathways.
can these signals be modulated?
the 2 somatic sensory pathway are the spinothalamic pathwasy and the posterior column medial lemniscal pathway.. they each have 3 orders of neurons
the sgnal bt the 1st and 2nd order neruon bodies as well as signal bt the 2nd and 3rd order somas can be modulated by other neurons (inhibited or excited)
where is the soma of the 1st order neuron of the somatic snesory pathway located?
the cell body f the 1st order somati sensory pathways is located in the posterior root ganglion (which is in the intervertebral foramina)
descrbie the location of the 2nd order neruon cell body and axon in sometic sensory pathwyas
in the someitc sensory pathways (the pathways for discriminitve touch and pain transmission) , the 2nd order neuron cell body is in the gray matter on the same side as the 1st order neuron. the axon, however, crosses the midline and ascends to the thalamus
where is the 3rd order neuron located of the somitc senory pathways
the 3rd order neuron in the somtic sensory pathwyas is located in the thalamus and carries the sinal to the primary somatosensory cortex (postcentral gyrus of the parietal lobe)
can the signals of the sometic sensory pathwyas be modulated?
yes. the signals in the sometic sensory pathways can be modulated due to the presence of synapses. there are 3 orders of neurons in the pahtwyas. the signal can be modulated at the synapses- such as bt the 1st and 2nd order neruons or bt the 2nd and 3rd order neurons. the signal is idulated by other neurons and the signal can be inhibited or excited
Pacinian corpuscles, Meissner corpiuscels, and Merkel nerve endings contribute to which pathway?
Pacinian corpuscels (vibration), Meisner corpuscels (discriminitve touch) and Merkel nerve endings (discriminitve touch) are received by the 1st order neuron of the posterior column-medial lemniscal pathways (the discriminitive touch pathway)
the fibers serving what region are carried in the fasciculus gracilis? to where do they travel (name of formation AND location)
the fibers carrying sensation from the lower limb and the lower trunk are carried by the fasciculus gracilis in the gray matter of spinal cord. the fasciculus gracilus travels to the nucleus gracilis in the medulla oblongata
the fibers serving WHAT region are carried by the fasciculus cuneatus?
-at what spinal level do they arrive?
-to where do these fibers travel (name of formation and location)
the fasciculus cuneatus carries fibers with sensory information from the upper limbs and upper trunk. ----These are seen in the spinal cord gray matter at and superior to level T6 (below, only fasciculus gracilis is visible as fibers for the upper trunk do not tavel to the lower regions...)
-- fasciculus cuneatus (a bundle of fibers) travels to the nucleus cuneatus in the medulla oblongata
in detail, describe the posterior column-medial leminsical pathway
this pathway is for dicriminitve touch.. carries a-delta fibers. the first order neuron is unipolar, and carries information to the gray matter of the spinal cord where it travels via fascicles (cuneate - upper body, fasciculus gracilis for lower body). the fascicles ascend in the spinal column throgh the grey matter until they reach their respective nuclei (nuclei gracilis or cuneatus) in the medulla oblongata (most ingerior portion of hte brainstem.. connects to the spinal cord)
- the second order neuron synapses with te 1st order neuron at the nuclei.., and the 2nd order neuron crosses the midline ((SENSORY DECUSSATION @ MEDULLA OB of the brainstem- then travel via the medial leminiscus in the medulla, pons, and midbrain >>and ascends to synapse in the thalamus @ the ventral posterolateral nucleus)
-the 3rd order neuron synapses witht he 3nd order neuron in the thalamus and carries the signal to the primary somatosensory cortex (aka postcentral gyrus in the parietal lobe)
T/F the 1st order neurons in both the dicriminitve touch pathwyas and the pain pathway (Ascending) are bipolar
FALSE. the 1st order neuron in BOTH the discriminitive touch and pain pahtways (both ascending, aka sometic sensory pathways) are UNIPOLAR.
describe in detail the spinothalamic pathway
he spinothalamic pathway is the pathway for both fast and slow pain.
fast pain signals are carried by a-delta fibers and slow pain via c-fibers.. these fibers are the 1st order neuron that arrive to the lamina (II and V, usually) of the posterior horn of the spinal cord (gray matter).
- the 1st order synapses w the second order neruon,(substnatia gleatinosa can modulate signal here ) the 2nd order neruon crosses the midline of the spinal cord(at every level in the naterior commissure) and ascendsvia the anterolateral pathway to the ventral posterior nucleus of the thalamus. in the thalamus, there is a second synapse bt the 2nd and 3rd order neuron
- the third order neuron carries information to the primary somatosensory cortex (aka postcentral gyrus, located in the parietal lobe) where it is conscious perception
in the posterior column-medial L pathway - what is the specific name for the location where the 2nd order and 3rd order neurons synapse int he thalamus?
in the thalamus, the 2nd order and 3rd order neurons of hte discriminitve touch pathwyas synapse at the ventral posterolateral nucleus.
what are the primary function(s) of the posterior column-medial lemnical pathways?
the main function(s) of the posterior column-medial lemniscal pathway is for Conscious procioception (signal arrives at primary somatosensroy cortec== therefore conscious) and discriminitive touch ("")
how can the posterior column medial lemniscal pathway be disturbed
demyelinating diseases like multiple sclerosis can disturn the discriminitve touch pathway-- symptoms include sensory ataxia = a movement disorder due to sensory impairment ((vs cerebellar ataxia where lesion in the motor system causes movment disorder)
T/F 2nd order neurons of the spinothalamic pahway projecting from the lamina of hte posterior horn can be modulated by the substantia gelatinosa
TRUE. the substantia gelatinosa (of lamina II) i able to modulate the 2nd order neurons of the spinothalamic pathway at the synapse ofthe 1st and 2nd order neruons of the pathway- substantia gelatinosa can inhibit or excite the 1storder neuron signal
T/F substantia gelatinosa can only inhibit the signal in the spinothalamic pathway
- what is the identity of the signal
FALSE.. while mostly mentioned as an inhibitor, substantia gelatinosa can inhibit or excite the signal in the spinothalamic pathwyas (at the synapse of 1st and 2nd order neuron)
excitory signal - glutamate (along w Substance P in the slow pain/C-fiber pathway)
inhibitory signal - GABA
T/F all pain fibers are myelinated
False. While the A-delta fibers (of fast pain, and discriminte touch) are myelinated, the C-fibers of slow pain are Unmyelinated
Of the pain fibers, which are myelinated and which are unmyelinated- if any..
There are two notable pain fibers covered: a-delta fibers of fast pain. A-delta fibers are myelinated, and c-fibers which carry slow pain. C-fibers are unmyelinated
what are 3 symptoms of normal hydrocephalus?
mneumonic: weird, wobbly, wet
symtpoms include confused and slow thinking (weird), magentic gait/difficulty walking and headache (wobbly), and incontinence (wet)
what kind of fibers serve muscles in terms of stretch and procioception sensory?
A-alpha fibers are fast conducting and deliver from muscles the sense of stretch and procioception (spatial awareness)
what sensations do free nerve endings detect?
free nerve endings detect sensatons of crude touch, temperature, and pain
what kind of fibers make up free nerve endings?
- and are they encapuslated?
free nerve endings are NOT encapsulated. they can be made up of c-fibers (unmyelinated) or A-delta fibers
how does local anesthesia work?
local anesthesia works by blocking sodium influx (during depolarization/blocking depolarization) at the unmyelinated portion of an axon (the node of ranvier).
at least 3 internodal segments must be saturated with the analgesic and the analgesic must penetrate all 3 layers of axon sheath- the epineurium (external) , perineurium (middle) and endoneurium (internal layer)
T/F local anesthesia is more effective with activated neurons
True! local anesthetic bonds more readily to receptors of activated neurons (hence why a dentist will grasp and flap a cheek near entrypoint of local anesthetic injection)
describe the axon reflex
in reaction to a skin lesion, the ara develops a red line due to dialtion of capillaries (in response). signal from the site of lesion are sent out in 2 fdrections -- orthodromic to the CNS and antidromic o neighoring cells. the nerighboring cells are stim. to release substance P and glutamate (pain sense) which cause the relase of histamine from mast cells, brandykinin and prostaglandinss which all contribute to inflammation. inflammation and the dialtion of arteriorles are the second state of the axon relfex that is FLARE (red line + neighboring tissue response). finally there is wheal.. the result of histamine and inflammation results in local swellin and release of plasma from dialted vessels.. area is white and puffy
what number of brodman's areas is the somatosensory cortex?
the somatosensory cortex is brodman's area #1
in which lamina does fast pain terminate vs slow pain?
fast pain terminates in lamina 1 whereas slow pain terminates in laminas 2 and 5
what causes an itch?
a small subset of somatosensory neurons. these produce and release Nppb (natriuretic polypeptide b) which results in itching
T/F pain controlled in teh facial region operates the same way as pain in the spinal level
True. pain in the facial region operates the same way as pain in the spinal level-- hence spinal level pain covered thoroughly in class
where is the nucleus raphe magnus located- and what is its significance?
the n. raphe magnus is located in the medulla oblongata. its significance is that it can activate the raphe spinal tract that acts to suppress pain by stimulating inhibitory interneurons in the substantia gelatinosa. the raphe spinal tract also releases serotonin which can also suppress pain.
Name 2 ways that PAG (periaqueductal gray) can be activated?
PAG can be activated by the slow pain (spinothalamic/ spinoreticular) pathways of the C-fibers.
PAG can also be activated by the amygdala to help suppress anxiety
T/F PAG can activate the raphe spinal tract
True. PAG can activate the raphe spinal tract and further suppress pain-- this is mportant in life-death situations and explains why a bullet wound can go unnoticed
define lower motor neuron
a lower motor neuron is what innervates striated muscle, and is the last neuron in a chain
name 2 types of lower motor neurons and what htey innervate
two types of lower motor neruons (which innervate striated -aka skeletal-muscle are alpha LMN and gamma LMN
alphaLMN innervate extrafusal muscle fibers
- gamma LMN inner intrafusal muscle fibers
what muscle fibers contribute to muscle tone? what happens if they are damaged?
both alpha and gamma muscle fibers contribute to muscle tone -- these are both types of lower motor neurons (the last neuron in a neuron chain that innerv skeletal/striated muscle). a lsion of htese fibers leads to ATONIA- lost of tone as well as
-areflexia (loss of hte myotatic stretch relfex)
-fasciculations (spontaneous m. contractions)
-muslce atrophy (loss of muscle tissue)
how is a flexor reflex different than the myotatic relfex?
the flexor relfex has 2 synapses- so there is ability to modulate (such suppresses urge to drop a hot plate)// vs myotatic reflex has only 1 synapse so no ability to modulate (such as knee-jerk)
what are the components of a flexor arc?
the flexor arc has 3 components - the incoming (afferent) cutaneous receptor, the interneuron, and the efferent a-alpha LMN fiber
why is the corticopsinal tract also called the pyrimidal tract?
the corticospinal tract forms the pyramid formaiton in the medulla - hence also called the pyrimidal tract
what pathway sends neurons directly to the motor neurons of hte hand (and a lesion in this pathway means permanent damage to hand motor skills)?
the corticospinal pathway sends axons directly to the motor neurons of the hands. a lesion of the corticospinal tract will result in permanent, forever deficient function of hand motor skills
what is the origin and termination of the corticobulbar tract?
use the name to figure out: cortico = cortex (cortico listed first, so orginates in cortex) and bulbar = brainstem.. so the corticobulbar tract travels FROM the cortex to brainstem (DESCENDING tractr)
which of Brodman's areas are related to motor functions? and name them
Brodman's ares #4 (the precentral gyrus == primary motocortex) and area #6 - the premotor complex center/ aka supplementary motor cortex are the 2 areas primarily involved in motor function
what is another term for the precentral gyrus
the precentral gyrus is also AKA the primary motor cortex
T/F both the primary somatosensory AND the primary motor cortex contain a homunculus (and the homunculus areas are given similar importnace in each)
TRue. the post and precentral gyrus areas both have a represnetative body called the homunculus.. that delieates the amount of control/ snesory info ascribed to the area. the homunculus has similar formation in both (ex - hands and lip areas of significant imporntace/ CNS control)
what does the parietal lobe have to do with the precentral gyrus?
the prietal lobe is 'the driver' and tell the precentral gyrus (the primary motor cortec) what to do
the fibers that contribute the most to the corticospinal (efferent/descending) tract originate where? - the second most abundant orignate from where?
the fibers of the corticospinal tract orginate from several locations. the largest contributor is hte primary MOTOR cortex with about 40% of the fibers present. the next most represented are the fibers of the primary somatosensroy cortex that contribute about 25% of the fibers of the corticospinal tract
what is the origination and termination of the corticospinal tract?
the corticospinal tract orignates in teh cortex and terminates in teh spinal cord -- this is an efferent/ descending pathway. use the name to figure out orginin/termination
T/F neurons in the autonomic ganglia are multipolar
True. neurons in the autonomic ganglia are usually multipolar
Are the postganglionic autonomic fibers myelinated or unmyelinated?
the postanglionic autonomic fibers are unmyelinated
T/F the adrenal medulla acts like a sympathetic ganglion
true. the adrenal medulla receives input from fibers of hte thoracic splanchnic tract = which a tract of the sympathetic nervous sytem
thoracolumbar refers to what division of hte ANS>
thoracocolumbar refers to the Sympathetic devion of hte ANS bc preganglionic fibers are located in spinal levels T1-L2, the thoracolumbar region
T/F the parasympathetic divsion of ANS has a thoracolumbar outflow?
False. the parasymtph divsion of ANS has a craniosacral ouflow from the CNS. the parasympth preganglionic fibers emergre from brain as CN (oculomotor 3, facial 7, glossopharyngeal 9, and vagus10) ad froms acral segments of hte spinal cord.
-- th sympthatic divsion has outflow from spinal cord levels T1-L2, the thoracolumbar region
what is the preganglionic NuT for both functional divisions of the ANS>
Acetylcholone is the NuT for botht he symtph and para. divsions of the autonomi nervous system
Name the NuT for postganglionic receptors for each division of the ANS
the postganglionic NuT for the parasymtph division is AcH (same as preganglionic NuT)
- for the symtph divison, the postganglionic NuT is norepinephrine
how many neurons are in the ANS effector chain?
the ANS effector chain has 3 neurons
1) from hypothalamus/brainstem to the brainstem/spinal cord preganglionic neurons
2) preganglionic neurons synapse w postganglionic fibers
3) postganglionic neurons send out fibers to target tissue
T/F flaccid paralysis is a sign of an upper motor neuron lesion
False. Spastic paralysis is a sin of an upper motor neuron lesion, whereas flaccid paralysis is a sign of Lower motor neuron paralysis
what is the Babinski sign indicative of (and describe)
the Babinski sign is indicative of an upper motor neuron lesion. this is where the bottom of the foot is stimulated w touch (such as a feather stroke) and the toes instead of curling down (normal), the big toe points up and the other toes fan out.
What kind of lesion will cause irreparable loss of fine motor control of the hand/fingers?
A lesion of the upper motor neuron will cause the irreparable loss of fine motor control of the hand/fingers
Name the symptoms of an upper motor neuron lesion
The symptoms of an upper motor neuron lesion include:
atrohpy of disuses (withers, but can recover)
loss of control of hte hand/fingers fine motor
Name the symptoms of a lower motor neuron lesion
the symptoms of a lower motor neuron lesion include: flaccid paralysis, areflexia, fasciculations, and muscle atrophy (complete loss of muscle use-- it dies..)
what kind of nervous pathway is a 2 neuron pathway
Efferent pathways have a 2 neruon chain
- the upper motor neuron originates in the premotor cortex (precentral gyrus) and terminates in the brain.. the second motor neuron AKA the lower motor neuron arses from the nerve nucleus (CN nucleus) and descends to the target tissue
T/F Horner's syndrome is a condition resulting from a lesion in the sympthetic region. what are the signs?
True. Horner's syndrome results due to a leison in the symptahtic nervous system. symptoms include, droopy eyelids (ptosis), sunken eyes,
how is the adrenal medulla an exception to the general scheme of the sympthatic chain?
the sympathetic neuron chain consists of 2 neurons- a pre and post-ganglionic neuron. HOWEVER, the adrenal medulla ia an exception bc there is only 1 neuron, the preganglionic neuron, that synapses directly onto the target effector organ- the adrenal medulla (so there is not 2nd postganglionic neuron, therfore it is an exeption to the general scheme
what is the "outflow" of hte sympthatetic nervouse system?
the outflow of the symtph NS is thoracolumbar -- meaning that the nwurons being in the thorax or lubar region, bt T1-L2 (in the lateral horn of grey matter)
what system has craniosacral outlfow - and what does this mean?
the parasympth divsion of ANS has craniosacral outflow -- meaning that the preganglionic nerve originate in the cranium (cranial nerves) or in the sacrum (S2-S4)
anhydrosis (dry skin), ptosis (droopy eyelids), miosis (small pupils) and endophthalmos (sunken eye) are symptoms of what?
anhydrosis, ptosis, miosis, and endophthalmos are all symptoms of Horner's syndrome which is a result of a lesion in the sympathetic nervous division
which four cranial nerves carry parasympathetic autonomic fibers?
cranial nerves CN 3 (oculomotor), 7 (facial), glossopharyngeal (9), and vagus (10) are the four cranial nerves that carry parasympathetic nerves
T/F multipolar neurons are associated with the efferent nervous system
True. multipolar neurons are assoc w the effernt nervous system
T/F unipolar neurons are assoc w the general afferent nervous system
True. unipolar neurons are associate witht eh general afferent system
Are microglia evenly distributed through grey and white matter?
Yes. Microglia are evenly distributed through grey and white matter
what is a key feature of microglia that helps in cell ID?
Microglia have characteristically flat/obling nucleus that helps in identification
in a histological tissue slide, how can oligodendrocytes be ID'd
oligodendrocytes have a tendency to line up, and this line appearance of stacked cells can be ID'd
WHAT TYPE OF NEUROGLIA can become phagocytotic?
the microglia upon activation can become phagocytotic and become APC
where can satellite cells be found?
Satellite cells can be found in the PNS wrapped around/covering a ganglion (function unknown)
what is the CT covering of a signle fascicle?
a fascicle is a bundle of nerve fibers.. and is covered by the perineurium layer (epineurium covers multiple bundles of fascicles along with vasucalr vessels, while endoneuium overs indiviudal nerve fibers
T/F unmyelinated axons in the PNS tend to cluster around myelinated axons for support
True. unmyelinated axons can be seen clustered around myelinated axons for support
what kind of conduction is found in unmyelinated axons?
- what kind of conduction is in myelinated axons?
unmyelinated axons have continuous conduction whereas myelinated axons have saltatory conduction (the signal jumps over hte node of Ranvier)
what nerve functions to accommodate near vision? How is this accomplished?
the oculomotor nerve CN3 accommodates near vision. This is accomplished by contraction of hte ciliary muslce to relax the lens, and constriction of the pupil // And convergence where the medial rectus of both eyes will contract to bring eyes closer medially to focus on nearby objects
T/F the ptosis exhibited in a CN3 lesion is less pronounced than that in Horner's syndrome (a sympathetic lesion)
False. the ptosis (droopy eyelid) resulting from a lesion of CN3 is much MORE pronounced than the ptosis in Horner's syndrome (via superior tarsal m)
T/F if a light is shone in a eye, the lack of constriction of the opposite pupil could be evidence of a CN3 lesion
True. CN3 operates so that both pupils in both eyes contrict upon just one eye stimulation by light. If both eyes do not display pupil constriction, it could be evidnece that there is a CN3 lesion
what type of neuroglia is predominantly found in the gray ,matter (vs white matter) ?
the astrocytes are predominalty found in gray matter (vs white) as htey are responsible for rpoviding an ideal enviro for neurons (cell bodies) to survive
where is the decussation of the efferent (descending) corticospinal tract seen?
the corticospinal tract decussates in the medulla (specifically in the pyramids)q
where does the pain modulating, raphe spinal tract decussate?
the raphe spinal tract does NOT decussate. it is an ipsilateral (same side) tract
T/F posterior and anterior root fibers make up the cauda equina?
True. posterior and anterior root fibers makeup the cauda equina that extends from the conus medularis to the filum terminale that anchors into the coccyx
what is the filum tmerinale?
the filum terminale is a thin strand of pia mater that anchors the cauda equina (anterior and posterior root endings from the spinal cord) into the coccyx
T/F the spinal cord is lined with dura mater
True. hte spinal cord is line with dura mater all the way to the coccxy
T/F.. The epidural space is an acutal space in the brain
False. the epidural space is a POTENtial space in the brain. However, the epidural space is an ACTUAL SPACE in the SPINAL CORD
Where is the terminal ending of the pain signal in the cortex?
In the cortex, the pain signal has many terminal locations to where it delivers the pain message
The Babinski sign is a tell-tale sign of:
The Babinksi sign is a tell-tale sign of: an UPPER MOTOR NEURON REFLEX
what is the significance of LR6 SO4
LR6SO4 is a meumonic to remeber the innervationof the extrinsic muscles of hte eye:
LR6- lateral rectus via CN^
SO4- superior oblique bia CN4
all other extrinsic eye muscles are innerv vi CN3, the oculomotor nerve
if the trochlear nerve is damamged, how will this be evident in the eye?
iF THE trochlear nerve (CN4) is damamged, then the superior oblique eye muscle of hte contralateral will be impacted. the eye will have difficulty looking downward and medially (and the eye will drift laterally without the tone of the SO) **head TILT= trochlear compensation ((not head turn, IS head TILT)
which extrinsic eye muscle keeps the eyelid propped open
think: the 3 roman columns prop open the yelid (visual mneumonic) == CN3, the oculomotor nerve via he Levator palpebrae muscle holds the eyelid open
what muscles of CN3 are controlled by the SE functional component of the nerve?
The somatic efferent functionality of hte oculomotor nerve is exressed in the control of hte extraocular muscles (except LR6, SO4) and the levator palpebrae (which props open the eyelid).
What is he nucleus and ganglion involved in the GVE functionality of CN3?
the GVE funcitonality of CN3
involves the Edinger Westphal nucleus (which is reponsible for hte accomodation reflex- cponstriction of pupils and relfaxation of lens for nearsightedness) and the ciliary ganglion
How can the eyes be evidence of an uncal hernation?
An uncal herniation can be caused by an epidural/subdural hematoma where pressure in the brain increases due to blood flow. The temporal lobe will be forced through the uncus opening which will compress upon the oculomotor nerve. This will cause a loss of parasympthatic functionality (oculomotor contricts pupil for accomodation.. so impariment of CN3 - impariment of contriction/parasymtph function) so sympthatic dominates and pupil will be in a dilated state
T/F the hypoglossa nerve (CN12) terminates on the motor neurons on the tongue -- and this is typical of most CN to do (terminate on the target)
2 part question:
1)True. the fibers of CN12 DO terminate directly on the muscles of the tongue- giving us fine motor control of the tongue muscles. However, FALSE, most ranial nerves DO NOT terminatre directly on the target.. instead, they USUALLY terminate on a nearby reticular formation
If there is an upper motor neuron lesion of the hypoglossa nerve, to which side will the tongue deviate?
- what about a lower motor nerve lesion of CN12?
If there is an UMNL of CN12, the fibers will not yet have decussated, and the tongue will be unable to protrude of the opposite sdie of the lesion therefore the tongue will be dominated by the working muslkces and deviate AWAy from the lesion.
- if it is a lower motor nerve lesion of the hypoglossal, the fibers will have decussated, so the tongue muscles on the same side of lesion will be malfunctional (and the tongue will deviate towards the lesion)
What is the only eye muscle that can direct the eyeball downward? Lesion to what nerve will impair its function?
The superior oblique is hte only eye muscle that can direct the gaze downwards. A lesion of the trochlear nerve SO4 will impair the SO muslce
lesion of what nerve results in horizontal diplopia - and to what direction will the head turn to relieve?
lesion of hte abducens nerve (impariment of Lateral rectus, LR6) will result in horizontal diplopia. turning TURN the head away from the lesion will resolve the double vision
lesion of what nerve will result in vertical diplopia, how can the diplopia be resolved?
lesion of hte trochlear nerve, CN4 controlling hte superior oblique M will result in vertical diplopia (the eye drifts upward laterally). To compensate, the person TILTS their head towards the shoulder of the intact eye (no lesion) *head tilt to shoulder indicative of a trochlear lesion
where is the nucleus of the oculomotor nerve?
the nucleus of the oculomotor nerve (oculomotor nuclear complex) is located in the midbrain tegmentum (towards the midline of the midbrain xsection)
what are the 2 nuclei of origin of the oculomotor nerve? - and their functionalities?
the 2 nuclei of origin of the CN3 are the edinger-westphal nucleus (autonomic, GVE)- lands on the ciliary gnaglion, control the contriction of the pupil and relaxation of the lens..
2) the oculomotor nucleus - which efferent control to the extrinsic eye muscles (except LR6SO4)
CN 7,9, 10 have the same 5 functionalities - what are they?
GSA, GVA, SVA,
CN 7,9,10 all have afferent functional components (GSA, GVA, SVA) -- what is the TERMINATION nucleus for all of the VISCERAL AFFERENT functionalities for all 3 of these nerves?
- what is the nucleus of general SOMATIC AFFERENT for all three nerves?
The SOLITARY NUCLEUS (in the medulla oblongata, medially located, looks like cat's eyes -is the termination nucleus ((gathering of nerve cell bodies in the CNS)) of CN 7,9,10 VISCERAL Afferent functional component - GVA, SVA
- the TRIGEMINAL SPINAL NUCLEUS is the nucleus of origina for the gneral SOMATIC afferent functionality of nerve CN7,9,10
what functionality and nerves is the nucleus ambiguus associated with? where is the nucleus ambiguus located?
the nucleus ambiguus is associated with the SVE (special visceral Effernt) functionality of CN 9 and 10.
CN9- iinerv the stylopharyngeus muslce
CN10-innerv the mm of swallowing and speech
what does the hypoglossal nerve innervate? name one of these muscles of importance and its function
the hypoglossa nerve innervates the muscles of the tongue -- one importnat m of htis group is the genioglossus which helps to push the tongue out.
what does the Vagus Nerve innervate through its 5 functionalities ((assign innervation with funcational component))
the vaugus nerve, CN10, has 5 functionalities::
GSA, GVA, SVA, SVE, GVE
GSA- ext ear, pharyx and larynx
GVA- thorax and ab viscera,aortic bodies
SVA- special-- epiglottal taste buds
SVE-mm of speech and swallowing
GVE- thorax and ab viscera
what does the glossopharyngeal nerve innervates through its 5 functionalities (assign innervation w functional component)
the glossopharyngeal nerve CN9 has 5 functonalities (same as CN7,9,10)
GSA, GVA, SVA, SVE, GVE
GSA- post1/3tongue,tympanic mmbrane, orophynx
GVA- carotid sinus(BP),carotid body(bloodCO2,O2)
SVE- stylopharyngeus m (via nucleus ambiguous)
GVE--parotid gland (nucleus = inf. salivatory to the otic gland to parotid)
what is the functionality of the trochlear CN4 and abducnens nerve CN6 (hint: both have only one and the same functional component)
think: both CN4 and CN6 give motor innervation of an extrinsic eye muscle, LR6 SO4
they both only have one functional component and that is SE, somatic efferent
Explain how the oculomotor nerve accommodates near vision:: (include functional components involved)
The oculomotor nerve has 2 fucntional components and both are involved in accommodation:
GVE- via the edinger westphal nucleus (to the ciliary gnaglion) == 1) constricts the ciliary muscle which results in relaxation of hte lens 2) constricts the pupil ((smaller aperture = more focused image, photography ))
SE - via the oculomotor nucleus == this functionality is motor control of extrinsic eye muscles.. for accommodation of near sight, the MEDIAL RECTUS muscles of each eye CONVERGE (convergence)
the oculomotor (oculomotor nucleus), the trochlear nerve (trochelar nucleus), and the abducnes nerves are all located in tegmentums -- name them:
the oculomotor nucleus - located in the MIDBRAIN tegmentum
the trochlear nerve nucleus- also located in the midbrain tegmentum
the abducens nucleus- located in the PONTINE tegmentum
what is the characteristic eye position of someone with an oculomotor lesion - why?
the characterisitic eye position of someone w an oculootor lesion is DOWN and OUT.
down- out bc hte medial rectus is nonfunctional so the lateral rectus (lateral pull via CN6) dominates and OUT bc the superior oblique (CN4 which pulls down is still fucntional while none of hte other exterinsic CN3 muslces are.. so CN4 and CN6 down and out actions dominate)
What 4 CN have only 1 functionality- SE? name the function
The 4 CN with ONLY the someatic efferent (motor control) functional component:
CN4- trochlear- superior oblique m, of ext. eye
CN6- abducens m- lateral rectus m., ext of eye
CN11- spinal accessory- SCM and trapezius mm
CN12- hypoglossal - m of hte tongue
T/F All cranial nerves have fibers from the brainstem?
False. CN11, the spinal accessory cord only has fibers from the spinal cord (and none from the brainstem). though the remianin g CN all have fibers from the brainstem
-- CN11, in its path, ascends from the spine up the foramen magnum and then descends out the jugular foramen... (('as if to get country club status : p - clark)
how can you tell if the CN11 has a lesion?
CN11 has SE functions for the SCM and trapezius mm. if there is a lesion, can assess via 2 tests:
1) trapezius :- shoulder will sag, and difficulty shrugging shoulders-esp agaisnt resistance
2) SCM- laying on side-- difficulty raising head- ESP agaisnt resistance
what is the solitary nucleus ? where is it?
the solitary nucleus is the TERMINATION point of Visceral Afferent fibers -- GVA and SVA-- of cranial nerves 7, 9,10// the solitary nucleus is 'cat's eyes' in the medulla **unique feature&& solitary nucleus SURROUNDS the solitary tract
what is the nucleus ambiguus? where is it found?
the nucleus ambigous id the nucleus of ORIGIN for special visceral efferent SVE fibers of CN9,10. ((which innervate CN(- stylopharygeus m ((action-- elevate pharynx and larynx)))
, and CN10-mm of speech and swallowing))
what is the GVE fucntion of CN9?
what is the nerve pathway?
The general visceral efferent pathwyas of hte glossopharyngeal nerve involves salivation via the parotid gland.
- the path of nerves: orignin: inferior salivatory nucleus > otic ganglion> parotid gland
what are the afferent and efferent components (nerves contributing) to the Gag Reflex
in the gag reflex,
-the afferent component is CN9 (post tongue)
-the efferent component is CN10 (mm swallowing)
what cell type helps make and circulates CSF?
Ependymal cells both make and help circulate CSF
?is the cell body of a neuron myelinated?
no- the cell body of a neuron is never myelinated
are all of the following characteristics abot neurons true?
1) neurons have extreme longevity
2)most neurons are amitotic (do not undergo mitosis)
3) neurons have a high metabolic rate
4)the cell body is the biosynthetic center of the neuron
All four statements regarding neurons are true:
they have extrmeme longevity, they are amitotic, they have high metabolic rates, and the cell body of a neuron is its biosynthetic center
T/F A dendrite is able to generate Action Potentials
False. Dendrites are NOT able to generate action potentials -- however, axons (the outgoing info process) IS able to generte and transmit AP
From what part of the neuron is th NuT released?
NuT of a neuron is released from the axon terminal (end bulb) upon depolarization (TRIGGERED BY INFLOW OF cALCIUM FROM VOltage gated vesicles) = this is chemical signaling
what is neurolemma?
neurolemma is the bunching of Schwann cell organelles and cytoplasm along hte periphery as the wrapped layers contain no organelles nor cytoplasm
what is the most abundant type of neuron in the humn body?
multipolar neurons are the most abundant type of neuron in the bidy
where are bipolar neurons found? are they abundant?
bipolar neurons are rare inthe body and found in specuial sensory organs
where are unipolar neurons found?
unipolar neurons are found in the PNS - mostly in the dorsal root ganglia of the spinal cord and sensory ganglia of CN (( afferent sensory-- 1st axon in the 3 neuron chain)
what kind of neuron is typically a motor neuron/function
typically motor neurons are multipolar nuerons
T/F the postganglionic neuron cn be an effector cell - name one postganglionic effector in the sympathetic system
THE ADRENAL GLAND is an example of a postanglionic effector organ
what are 3 ways tha t NuT can be cleared out of the presynaptic cleft?
th NuT released by the presynaptic axon terminal can be removed from the cleft by 1) degradation via enzymes 2) reuptake by astrocytes or the presynaptic terminal 3) diffusuon away from the synapse
where are satellaite cells found?
satellite cells are found in the PNS wrapped around ganglia ((exact function unknown)
does a nerve contain blood vessels and lymphatic vessels?
yes, nerve bundles (wrpped most superficially by epineurium connective tissue) does include blood vesseks, lymph vessels CT Scwan cells and neuron processes