Week 1 Final Exam Flashcards Preview

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Flashcards in Week 1 Final Exam Deck (91):

A major fiber bundle associated with the Intersegmental reflexes is the ___, which is distributed around the periphery of gray matter in the spinal cord and is continuous superiorly with the reticular formation

Fasciculus proprius


******The Conscious sensory pathway is VERY FUCKING IMPORTANT *********

A ___ neuron is a pseduounipolar neuron who's cell boy is located in a spinal ganglion. The ___ process is associated with a receptor and the ___ process enters the CNS and bifurcates to ascend and descend a variable number of spinal cord segments

The primary neuron eventually terminates upon a ____ neuron, which is located in the ____ (for the pain and temp pathway) or the ___ (for the proprioceptive pathway). The secondary neuron always ___ and ascends as a ____ and terminates upon a tertiary neuron in the ____ (it also sends collateral fibers to the reticular formation -RF and tectum)

The tertiary neuron projects to the ____ via ____ of the internal capsule and corona radiate

^** Also note pain/temp and proprioception/2-pt tactile are the main things tested

Primary Neuron, peripheral (dendrite), central (axon)

Secondary, Spinal cord, Medulla, decussates (crosses), lemniscus, dorsal thalamus

Primary somesthetic cortex, thalamic radiations


*******Secondary axons in the conscious sensory pathway that have already crossed midline (aka convey info from the opposite side of your body) is called a ___ system so if you cut a lemiscus, you get contralateral deficits *******

A lesion to a primary neuron results in ___ deficits and secondary and tertiary are ___ deficits


Ipsilateral, contralateral


____ neurons are the final effectors of the motor system and their processes form the motor nerves that innervate ********** ___ muscles*******

^*** It is important to realize these are simply the FINAL COMMON PATHWAY, the fact that they are called LMNs does not be they are inferior to anything versus superior... It just means they are the last neurons to innervate the striated muscle

^* Upper motor (premotor) neurons and their descending processes form the rest of the motor system (in other words, it goes directly to the muscle but does not innervate the muscle aka UMNs go to LMNs)

***There are two types of LMNs, _____ motor neurons innervate extrafusal or skeletal muscle fibers and ____ motor neurons EXCLUSIVELY innervate the modified muscle cells (intrafusal fibers) that form part of the proprioceptive neuromuscular spindles ******

^********** Activating ___ efferent motor neurons increase muscle TONE and tension

Lower motor, Striated skeletal

Alpha, Gamma



___ portions of the ___ horn (lateral motor cell column) are always the distal upper extremities

Lateral, anterior (ventral)


LMN paralysis results from the destruction of the motor neurons or the axons of one or more of the crania or spinal motor nuclei

1) This results in ____ (muscle completely limp and no resistance to passive movement)

2) Absence of the associated muscle reflex

3) Loss of muscle tone due to destruction of gamma motor neurons

4) Loss of stimulation from the motor neuron causes the denervated muscle to ___

5) Twitching due to hypersensitivity of the motor end plate

1) Flaccid paralysis

2) Areflexia

3) Atonia

4) Atrophy

5) Fasciculations


*****An important LMN clinical example is ___, which involves the motor neurons of the _____ and the ____ motor nuclei*****

Poliomyelitis, anterior (ventral) horns, cranial nerve


The corticospinal tract (CST) consists of large pyramidally-shaped neurons (cells of Betz) located in the ____ then the CST located in the ___ descends through the precentral gyrus -> posterior limb of internal capsule -> Cerebral peduncle (mid 3/5th) -> Pyramids -> to the pyramidal decussation where it crosses over and then has 85% of its fibers form the ____ ***(note this is occurring in the Spinal Cord)*** and the other 15% forms the anterior corticospinal tract (ACST)

^** The CST terminate mainly in LMN pools and the LCST fibers mainly get distributed to the cervical and lumbosacaral enlargements

Primary motor cortex, brain (or brain stem), Lateral Corticospinal tract (LCST)


LCST are primarily involved in the control of ___ musculature

So, Unilateral lesion of the LCST results in ___ paralysis of paresis of the distal limb musculature innervated by those spinal segments ___ the level of the lesion

Distal Limb

Ipsilateral, below


____ paralysis is commonly due to interruption of the motor cortex, CST, or Corticobulbar tract

^** Since remember, the descending fibers from the CST are going to LMN pools so if you cut that descending info to the pools of neurons by cutting the CST, they start to get hyperactive...

Signs and symptoms include spastic paralysis of the axial and proximal limb musculature (and some degree of distal limb muscles effected), Hypertonia, Hyperreflexia, Babinskis sign, Clonus, Rigidity, and Disuse atrophy

^***** AKA the flexors of the upper extremity and the extensors of the lower extremity (the antigravity muscles)



For a spinal cord injury, there are three phases of events

First, the patient is in ____ with areflexia, atonia, and flaccid paralysis.

After a few weeks or months, the patient's spinal reflexes return due to the reactivation of the intrinsic circuits of the spinal cord ___ to the lesion (aka the LMN becomes hyperactive)

After 1-2 years the affected muscle groups will exhibit spasms of the extensors, flexors, or remain flaccid

Recovery from spinal shock can occur via sprouting below the level of the transection and expression of the receptor phenotypes that are self-activating (a serotonin receptor)

^** So the important details are that it occurs INSTANTLY, and is reversible and occurs following ___ lesion

^** So if someone displays some sort of reflex that occurs beneath the level of the lesion, they are out of spinal shock

Spinal shock




____ is abnormal, passive resistance to movement in ONE direction

___ is abnormal, passive resistance to movement in ALL directions




Name if the characteristic is part of an UMN or LMN lesion

1) Paralyzes movements in hemiplegic, quadriplegic, paraplegic distribution (not individual muscles)
2) Paralyzes individual muscles or sets of muscles in root or peripheral nerve distributions
3) Atrophy of disuse only (late or slight)
4) Atrophy of denervation (early and severe)
5) Fasciculation and Fibrillations
6) Hyperactive DTRs
7) Hypoactive or absent DTRs
8) Clonus
9) Clasp-Knife spasticity
10) Hypotonia
11) Absent abdominal-cremasteric reflexes
12) Babinski reflex

1) UMN
2) LMN
3) UMN
4) LMN
5) LMN
6) UMN
7) LMN
8) UMN
9) UMN
10) LMN
11) UMN, and LMN?
12) UMN


************** Name the important regions of the spinal cord

1) ___ roots

2) Posterior columns located in the posterior region. These are important due to the ascending sensory tracts for ____ and ____, along with vibratory sensations

3) Lateral funiculus which includes the ___ tract. There are descending ____ tracts for volitional control of limb musculature, along with descending UMN tracts for autonomic control of (In other words, UMN are important for the lateral region

4) The Anterolateral region has ascending sensory fibers for ___ and ___, along with crude (light) tactile sensations. Decussating fibers are in the direct pain and temp pathway.

5) The Anterior region aka the Anterior funiculus, has ____ in the ___ horn of the spinal cord.


1) Dorsal

2) proprioception, 2pt tactile discrimination

3) LCST, UMN, bladder and bowel

4) Pain and temperature

5) LMN, anterior (ventral)


There are 5 basic components to a reflex arc, including the Receptor (free nerve endings for pain sensations), Afferent Neuron (Dorsal root ganglion neuron), Interneuron, Efferent Neuron (Alpha of Gamma motor neurons in motor nuclei or columns), and Effector (motor end plate at NMJ)

An interneuron in a reflex pathway terminates directly OR indirectly upon a ___ horn cell

The course and termination of an interneuron determines the pattern of the reflex response, if it stays in the same level as the afferent stimulus it is called a ___ reflex, if it extends the influence of the incoming signal among more than one spinal segment it is called a ___ reflex, and then both intra and inter-segmental reflexes can also have a ___ reflex component if the reflex is conveyed to the other side by way of a commissural neuron

Ventral (aka anterior)

Intrasegmental, Intersegmental, Contralateral


Sharp, Pricking, Highly localized pain, along with thermal sensations, are conveyed via the ___ pathway (fast pain) and is part of the convergent ___ system and the peripheral processes of the primary neurons are ___ fibers

Burning pain, deep, dull, aching, and diffuse pain are conveyed via the diffuse ____ system (Slow pain) and is part of the ____ system which means it is polyneuronal, and polysynaptic divergent pathway. The primary fibers are unmyelinated type ___ fibers

Direct spinothalamic, neospinothalamic, A Delta

Indirect spinothalamic, Paleospinothalamic, C


For the Indirect Spinothalamic pathway, the primary fibers are unmyelinated, type ___ fibers with a slow conduction rate. When they enter the spinal cord they bifurcate and ascend and descend a variable number of spinal segments in the ____ of ___.

Primary fibers also send thousands of collateral terminals to the ___ where the C type fibers also terminate (note that some fibers can ascend into the direct spinothalamic system as well via fibers sent to the substantia gelatinosa)

Secondary axons from the nucleus proprius course bilaterally in the anterior, lateral, and posterior regions of the ___ and most fibers terminate on interneurons to form the neuronal patterns for the complex, called intersegmental reflexes

The fasciculus proprius is part of a diffuse neuronal net called the ____, which surrounds the gray matter of the spinal cord and extends rostrally through the core of the brainstem to the thalamus

***** Finally, the fibers terminate at the _____ and ____, bilaterally *********

Therefore, slow or visceral pain is perceived at the thalamic level

Dorsolateral fasciculus of Lissaur

Nucleus Proprius

Fasciculus proprius

Reticular formation

Hypothalamus and Centromedian Nucleus of the Dorsal Thalamus


A unilateral lesion of the Spinoreticular fibers results in ____ sensory deficits since it is to bilateral and diffuse to be affected by unilateral lesions

A unilateral lesion of the Lateral Spinothalamic tract results in ___ loss of pain and temp sensation ___ sensory dermatomal segments below the level of the lesion

^** The LSTT can be transected for the relief of intractable pain and is done so in the anterolateral quadrant of the cord, 2 segments ___ and on the ___ side of the area of pain and this is called an anterolateral cordotomy


Contralateral, 2

Above, opposite


The direct spinothalamic pathway is a conscious sensory pathway and involved in "fast" pain


The receptors for Fast pain/Temp pick up the signal and send their info to the spinal cord. The primary neurons cell body is located in a ___.

******The central process then enters the spinal cord and bifurcates to ascend and descend ___ spinal cord levels and is conveyed by the ____ to the secondary neuron located in the ___ *********

Then the secondary axons decussate within 2 spinal cord levels of the incoming stimulus and ascend via the ___ and ____ to the ____ where they synapse on the tertiary neuron (located in the ___).

The tertiary neurons then send their axons to the ___ (which is the postcentral gyrus)

Spinal ganglion

2, Dorsolateral Fasciculus of Lissaur (DLF), Substantia Gelatinosa (SG)

Spinal Lemniscus and Lateral Spinothalamic Tract, Ventral Posterior Lateral Nucleus (VPL), Dorsal Thalamus

Primary Somesthetic Cortex


*************So once again, in the ____ division of the dorsal root, fibers enter the _____ and conveys pain and temperature information

It goes up and down ___ segment levels


*******This is important because a lesion of the lateral spinothalamic tract will result in a contralateral loss of pain and temperature 2 sensory dermatome segments below the level of the lesion***************

Also realize the divison of the dorsal root that the fibers enter is important because if the fibers enter the ___ division of the dorsal root, they convey 2pt tactile discrimination, vibratory information, and proprioception

Where as if they enter the ___ division of the dorsal root, they convey pain and temperature ********

Lateral, Dorsolateral Fasiculus of Lissaur





If a patient has congenital absence of ____ fibers they are insensitive to pain due to the fact that it allows nonnociceptive fibers -ABeta fibers (fibers that do not convey pain) to exist and these fibers ___ the gate

^**This concept is better explain in a latter flashcard

In Herpes Zoster, Nonnociceptive ABeta fibers are compromised and therefore the gate is ___ and this causes ___ sensitivity to pain

C type fibers, close

Open, Increased


WILL BE TESTED ON***************

A disease in which longitudinal cavities form in the cervical region of the spinal cord (upper cord) is called ____ and can occur from a protrusion of the cerebellar tonsils through the foramen magnum... It associated via enlargement of the syrinx

It can result in 4 possible effects, name which 4 things it can effect than answer the question


1) If the ____ is destroyed, bilateral loss of pain and temperature sensations to the upper extremities can occur (since remember, this is occurring in the cervical regions of the spinal cord)

2) If unilateral or bilateral destruction to the ___ occurs, spastic paralysis, hyperreflexia, hypertonia of the lower extremity can occur

3) If the ___ are destroyed unilaterally or bilaterally, lower motor neuron paralysis (flaccid paralysis, atrophy, areflexia, and atonia) can occur in the associated upper limb musculature

4) If the ___ are destroyed, ipsilateral anesthesia (proprioceptive and 2 pt tactile sensations) below the level of the lesion will occur ******


AWC, LCST, Anterior Horns, Posterior Columns


1) Anterior white commissure

2) Lateral Corticospinal tracts

3) Anterior Horns

4) Posterior Columns


The ___ pathway is the major pathway for crude tactile sensations, pressure, and light (passive touch)

For the crude tactille pathway, the primary neuron body is located in the ___ and the central process of the primary neuron is called a ____ fiber and located in the posterior column

The primary axons enter the posterior ___ and ascend 6-10 segments while sending numerous collateral terminals to secondary neurons located in the ipsilateral ____ and the ___

The secondary neurons than cross over in the anterior white commissure and form an ascending tract called the ____ and then in the medulla the VSTT joins with the LSTT and Spinotectal fibers to form the ___

The Spinal Lemniscus terminates on tertiary neurons located in the ___ of the ___

Ventral Spinothalamic Pathway (VST)

Spinal ganglion, short ascending fiber

Column, Nucleus proprius and intermediate gray mater

VSTT (Ventral Spinothalamic Tract), Spinal Lemniscus

VPL (ventral posterior later) nucleus of the dorsal thalamus


****A unilateral lesion of the VSTT causes _____ loss of crude touch sensations due to the fact that fibers ascend in BOTH the posterior (primary fibers 6-10 segments) and anterolateral faniculi (Secondary fibers) and this separation of info provides the system with a degree of bilaterality ****

A unilateral lesion of the spinal lemniscus results in ____ hemianalgesia (inability to feel pain on one side of the body) and thermal hemianesthesia (loss of thermal sensation on one side of the body)

No (or very little)



For proprioception and 2pt tactile discrimination, the system is called the ____

The primary neuron's peripheral processes start off in the ____ and the central processes of the primary neurons course through the ____ division of the dorsal root and enter the posterior columns where they then immediately segregate into the appropriate posterior ____ along with ascending and descending fibers

If the information is from the lower extremity, the fibers will form and ascend in the fasciculus ____ and if the information is from the upper extremity the fibers will form and ascend in the fasciculus ____. These primary fibers that ascend are specifically called _____ fibers in the posterior column

The Long ascending fibers travel to the medulla, where the primary axons in each of these fasciculi terminate onto secondary neurons in their corresponding ____ for the fasciculus gracilis and the ___ for the fasciculus cuneatus

Now the secondary neurons travel in the medulla and form the nucleus gracilis and cuneatus decussate as ___ fibers and form the _____ (contralateral or ipsilateral?), ____

As the ML ascends, the position of the fibers from the upper and lower extremities rotates 90 degrees in relation to each other and the ML terminates upon tertiary neurons in the ___ of the ___

The Tertiary neurons the project from the VPL nucleus to the ____ via internal capsule and corona radiata

Posterior column/medial lemniscal

Spinal ganglia, Medial, funiculus

Gracilis, Cuneatus, Long Ascending Fibers

Nucleus gracilis (aka clavum), Nucleus cuneatus (aka tuberculum cuneatum)

Internal arcuate fibers, Contralateral medial Lemniscus (ML)

Ventral posterior lateral nucleus (VPL) of the thalamus

Primary Somesthetic cortex (Postcentral gyrus)


****_____ cerebellar modalities including the Precise Proprioception of Individual muscles for the Lower extremities are conveyed through the ___ tract and for the Upper extremities they are conveyed through the ___ tract ******

Unconscious cerebellar modalities including Gross Proprioception of the Whole Limb is conveyed through the ____ tract for the lower extremity and the ___ tract for the upper extremity *************

Unconscious, Dorsal Spinocerebellat tract (DSCT), Cuneocerebellar Tract (Direct Arcuate fibers)

Ventral Spinocerebellar tract (VSCT), Rostral Spinocerebellar tract


Complete unilateral lesions of the posterior column results in an ____ loss of proprioception, 2 pt tactile discrimination and vibratory sensations ___ the level of the lesion

A lesion of the fasciculus gracilis results in ____ loss of Proprioception, 2pt TD and Vibratory sensations from the ____ half of the body and extremity

A lesion of the fasciculus cuneatus results in ___ loss of Proprioception, 2pt TD and Vibratory sensations from the ___ half of the body and extremity

Unilateral lesion of the medial lemniscus results in a loss of proprioception, 2pt TD and vibratory sensations on the ___ side of the body and limbs

Ipsilateral, below

Ipsilateral, lower

Ipsilateral, upper



Sensory (afferent) neurons have specialized channels that open or close in response to a stimulus (like a touch stimulus that deforms the cell membrane and opens a channel) and the opening of these channels lets in ions to cause and a sub-threshold response or EPSP occurs due to a depolarization, which is called a ___

Generator Potential


*******The Pacinian Corpuscle responds to ___/___ and this leads to a ____ of the membrane and fluid, which causes the opening of mechanosensitive ___ channels on the membrane and its influx to cause a generator potential and if its big enough an AP will occur

If the stimulus is maintained, the AP will die down and ___ occurs due to rearrangement of the membrane and the fluid

Once the stimulus is removed, there can also be APs generated as the receptor reforms and this is called an ___*******

Touch/pressure, Mechanical deformation, Na+




The most important way our brain knows about intensity is the number of ___ and if the intensity increases to much, we start to see ___ discharge

The ___ of receptors firing also increases with increased intensity

Action Potentials, patterned



The Just Noticeable Difference is the smallest difference that can be detected and normally a change of about ___% is required for conscious recognition of the change



K and A are constants and vary depenidng on the type of sensory receptor

Muscle senses have both K and A close to ___, which means that our ___ intensity matches the ___ intensity VERY closely

This is different than the cutaneous senses, which have a K and A that is more variable and therefore what we perceive may diverge from the actual rather substantially

*** So in other words, in terms of the strength of the input, there is a relationship between what is perceived vs what actual is the strength, but it is only in the muscle senses that they go linear to each other... Other senses are not necessarily linear********

1, perceived, actual (measured)


Pre synaptic inhibition arises from an ___-___ synapse

This is due to a post-synaptic cell being a pre-synaptic terminal and this results in reduced NT release from the inhibited Pre-synaptic terminal

Pre-synaptic inhibition occurs between neighboring receptors at the ___ synapse in their pathway and this increases the brains ability to ___ a signal

^**The Thalamus is also important in this


First, localize


The somatosensory cortex aka the postcentral gyrus has columns and each column deals with ONE sensory modality in ONE part of the body (somatotopic)

Sensory information arrives at its respective column in layer ____ via the ___

4, thalamus


___ is involved in the integration of the information for position sense as well as size and shape discrimination

However, it is NOT complete (in other words, you know the characteristics of the object in your hand but not what it is)

S1 feeds information to ___, which is required for ___ touch and also plays a role in memory

^** If you damage S1 you can't get info to S2, but if you damage S2 you don't impair the function to S1

**So if you damage S2 you can describe the object in your hand as having rounded corners, hard, etc... But you cant identify it without seeing it, you can't compare it to anything without seeing it, and you can decide to remember what that object was***


S2, Cognitive (aka you know what the object is simply by touching it)


The ___ association cortex is required for high-level interpretation of sensory inputs (which means it receives input from different cortical areas, including S1 and S2)

The PTO is important for spatial coordinates of self/surrounding objects, naming objects, and other aspects of cognition

PTO (Parieto-temporal-occipital)


The law of specific nerve energy states that the stimulation of a sensory pathway at any point leads to the perception of a sensation that is dictated by the nature of the receptor that ___ the pathway

(In other words, no matter where along the pathway a sensory fiber is turned on, the brain senses that fibers response)

^**For example, if you stimulate the cortical column that receives input from the pacinian corpuscle, you will perceive the sensation of ___

Similar to this, the law of projection states that no matter where along the path we stimulate fibers, the perceived sensation is always referred back to the area of the body in which the receptor is located

^** For example, if we stimulate the cortical column from a pacinian corpuslce in the left index finger, you will perceive the touch as occurring on your left index finger

*****So to summarize, the law of ___ tells us what we will perceive and the law of ____ tells us where we perceive it at******


Light touch

Law of specific nerve energies, law of projections


___ fibers are small, sparsely myelinated, and conduct fast/sharp pain

___ fibers are unmyelinated and associated with dull/slow pain

Both have slow conduction velocity, and hard threshold to activate


C fibers


Many mixed modality nociceptors express mechnaosensitive __ channels called ____ and the mutation in this channel leads to an absence of ___ sensation or a ___ syndrome (aka neurons are activated inappropriately so you get an overwhelming pain)

Na+, SCN9A (aka Na1.7), pain, paroxysmal pain


The sides of the nociceptors in the skin, along with the sides in the spinal cord (aka they are on both sides) can have lots of ___ receptors (in addition to their stimulus-gated channels) which can alter the sensitivity of the nociceptors to input and respond to things like Substance P, Kinins, ATP, and H+

When the chemicals bond and change the sensitivity of the nociceptors (usually an increase), it can activate ___ nociceptors

^** These substances are produced by either the damaged tissue or the bodies response to the damage which release the substances into the periphery and spinal cord

Ligand-gated receptors



The first synapse for the nociceptors occur in the spinal cord and the AlphaDelta cells release ____ that act on ___ receptors on the second order neuron

The C fibers release ___ and ___


Substance P and EAA


In the spinoreticulothalamic pathway (slow pain) the nociceptors synapse on an interneuron in the spinal cord ___ crossing and ascending to the reticular formation



Afferents from the viscera organs travel with ___ nerves instead of the two spinal pathways we've talked about and also have additional synapses within the hypothalamus and medulla

^** These additional synapses are important for changes associated with visceral pain like diaphoresis and altered blood pressure



S1 and S2 receive input from the nociceptors and play a role in ____ pain so if you were to damage one of these you would still feel the pain, just not know where it's coming from

The ___ is also important in the interpretation of nociceptive inputs and integrates all signals related to pain (asymbolia)


Insular Cortex


Many nociceptive inputs go to the ___ where emotional components inherent in the sensation of pain are produced



The gate theory of pain is based on the idea that other somatic inputs can alleviate pain (such as rubbing an area)

So when a rubbing motion for example is done, ___ fibers are activated and these fibers have a branch that travels in the dorsal columns to relay the pressure information (like normal), AND a branch in the spinal cord that synapse on an ___, which synapses on a ___ order neuron that came from a ___ fiber

The AlphaBeta fibers release ___ and this activates an ____ interneuron in the spinal cord and the interneuron releases ____ to inhibit the activtiy of a second order neuron in the pain pathway

^** So in conclusion, sensory input from a close by area inhibits the second order neuron in the pain pathway so not as much nociceptive information gets relayed to the brain***

AlphaBeta, Interneuron, second order, C fiber

EAA, Inhibitory, glycine


Neurons in the ____ are the main location for modification of painful inputs via descending mechanisms

These neurons are activated by opiate, EAAs, and Cannibinoids, and once activated they send axons to the ___ and releases ___ which bind to ___ receptors

Now the activated Raphe neurons travel to the spinal cord and release ___, which activates ____ and this releases ____ and activates ____ receptors on the presynaptic terminal of the C fibers

This causes pre synaptic inhibition that reduces the release of ___ from the C-fiber (nociceptor) and reduces pain transmission (remember C fibers release substance P and EAAs)

Periaqueductal Gray (PAG)

Midline Raphe Nuclei, Enkephalin, Mu

Serotonin, inhibitory interneurons, opiates, Mu

Substance P


____ pain is poorly localized, very few receptors and almost all ___ fibers, stretch receptors are also present and often the pain is referred

Visceral inputs ____ (Can or Can't) be refined like cutaneous inputs can

Refered pain occurs due to the fact that previous experience has taught the brain that the shoulder is more likely to experience pain than the heart for example

Also, nociceptors from visceral pain can converge on the same interneurons in the spinal cord of somatic information (like from cutaneous pain)


C fibers



A reflex occurs ___ than the fastest voluntary motion

Reflex activities are precise motions in response to afferent stimuli, mediated at ___ levels of the CNS, rapid initiation, and ___ (Can or can't?) be elicited even when someone is unconscious

Volitional activities originate in ___ areas associated with judgement, initiative, and motor control; have longer onset latency due to processing, and ___ (can or can't?) occur when someone is unconscious


All, can

Cortical, Can't


**** The myotatic (stretch) reflex is a ___synaptic, ___ reflex

It is the contraction (shortening) of a stretched muscle due to a protection mechanism from tearing (due to stretch)

Monosynaptic, segmental


Muscles are made up of extrafusal fibers and intrafusal fibers and the intrafusal fibers make up the ____ and have both ___ component located in the middle of the fiber and ___ component located at the edges of the fiber and has actin and myosin and behaves like skeletal muscle

Muscle spindle, afferent sensory, efferent motor


The sensory component itself is not contractile and sensitive to length and also has 2 components called the __ fiber and the ___ fiber

Around the sensory components of both the chain and bag, there is the ___ afferent which is a ___ fiber, large, myelinated, and sensitive to ___

There is also a ___ afferent that innervates ONLY the ___ fiber and is sensitive to ___

Nuclear bag, nuclear chain

Primary, 1A, the length of the muscle and how fast the length is changing

Secondary, Nuclear Chain, the length of the muscle ONLY (static component)


The motor component of the muscle spindle consists of contractile elements and is the same as skeletal muscle, innervated by ___ and controls the length of the ___ portion (AKA it renders the sensory portion more sensitive to a superimposed stretch)

Gamma motoneurons, sensory


The 1A fibers come into the spinal cord and active ___ via EAA at Non-NMDA receptors

Also when you elicit the stretch reflex, the antagonist muscle during the contraction is ____ (aka also stretched) and this occurs via fibers from the original 1A going to an interneuron of the antagonist muscle and inhibiting the alpha motorneuron of that muscle in a process called ___

Alpha Motorneurons

Relaxed, reciprocal inhibition


The ____ reflex is a sudden (abrupt) relaxation of a contracted muscle in order to protect the muscle from damage due to excessive force in contrast to the myotatic reflex which is a passive stretch

Therefore this reflex is a ___synaptic, ___ reflex

It is a ___ fiber that goes to the spinal cord

Golgi tendon

Polysynaptic, segmental



For the Golgi tendon reflex, the 1B comes into the spinal cord, releases EAA onto an ___ which is ____ by releasing ___ towards the alpha motoneuron and causes less APs and therefore it decreases muscle ___

Internerous, inhibitory, Glycine, tension


Loss from all structures Rostral to the pons results in ___

This results in rigidity, aka resistance to motion in all directions, due to maintained muscle contraction causes via continuous activation of ___ via the brainstem (aka contraction of muscles in the absence of other stimuli)

This also results in spasticity which is a resistance of motion in a given direction, due to continual activation of the ____ and hyp___activity of the myotatic reflex

Decerebrate posturing

Alpha motor neurons

Gamma motorneurons, hyperactivity

^** remember the gamma motorneuron contracts the motor element of the interfusal fibers and increases the sensitivity of the sensory portion so the nuclear bag and chain fibers are constantly in a state of stretch so if you try to further stretch their muscle it was INSTANTLY come back (since its so sensitive)


For spasticity, via the activation of the gamma-motorneruons, this occurs in the ___ region

*********^ This region is spontaneously active, however in normal people it is countered by the action of the ___ region and this region requires activation from ____ regions, so if you mess up those regions you lose the inhibitory effect*******

So in the case of a diver who fucked up his head, he lost all the regions that activated the inhibitory brainstem region and now you get the brainstem facilitatory region active and spasticity results and therefore the patient resists a passive stretch in their muscles

Brainstem facilitatory region

Brainstem inhibitory, cortical


Flexion of the upper limb joints, and extension of the lower limbs is called ___ rigidity

It is also dependent on ___ position

This normally results from strokes in the vicinity of the ___

So in a unilateral situation, the arm on the effected side is ___ and the leg is somewhat extended

Decorticate posturing


Internal capsule, flexed


Name if the response is cortical, brainstem/midbrain, or spinal reflex

1) Vestibular
2) Placing reaction
3) Crossed extensor
4) Yawn/suckle and eye/head movements
5) Stretch (myotatic)
6) Hopping reaction
7) Righting reflex
8) Golgi tendon reflex

1) Brainstem/midbrain
2) Cortical
3) Spinal
4) Brainstem/Midbrain
5) Spinal
6) Cortical
7) Brainstem/midbrain
8) Spain


The sensory nucleus in the spinal cord that handles visceral reflexes is the ___

VAN (Visceral afferent nucleus)


******The transition between fasciculus gracilis and fasciculus cuneatus is about at the level of the ___ spinal cord*******

^ So below the level of T6 you have NO fasciculus cuneatus ?



The primary neuron cell body for Visceral pain is located in the ___, then the central process enters the spinal cord and is conveyed via the ____ where it merges with secondary neurons located in the ___

Fibers from the VAN then get conveyed via the ____ to the ____ and ____

Fibers from VAN can project to 3 palaces

1) The ___ reflex pathway is when fibers project to the alpha and gamma motor neurons and can therefore result in muscle spasm or increases muscle tone

2) The ___ reflex pathway is when fibers project to the intermediolateral cell column for a sympathetic response or the the parasympathetic nuclei in the brainstem or spinal cord (dorsal motor nucleus of the vagus and sacral autonomic nucleus)
^**Thoracolumbar = Sympathetic
Craniosacral = Parasympathetic

3) The ___ pathway is when fibers enter the adjacent fasciculis proprius and bilaterally ascend to the brainstem reticular formation or the hypothalamus as part of the spinoreticulothalamic pathway

^** This is what can cause Visceral Paain referring to somatic pain

Spinal ganglion, Dorsolateral Fasciculus, Visceral Afferent Nucleus (VAN)

Reticular formation, Centromedian nucleus of the Dorsal thalamus and Hypothalamus

1) Visceral-somatic
2) Visceral-Visceral
3) Spinoreticulothalamic


A unilateral visceral stimulus projects bilaterally through the spinoreticulothalamic pathway, so a unilateral lesion causes ____ loss if information sent



Cranial ganglia and regions innervated by GVA fibers have pseudounipolar neurons associated with the cranial nerves ___, ___ and ___ and the central processes of the GVA fibers travel and terminate in the ____

For gustation (taste) fibers from the NTS project to the superior salivatory nucleus which innervates the ___ of the tongue and the Inferior salivatory nucleus which innervates the ___ of the tongue

The autonomic pathway has NTS fibers project to the ____ and is important in cardiovascular responses, AND ****GERD/Lower esophageal sphincter responses******** since it inenrvates the larynx, pharynx, thorax, and abdomen
^**Remember ANS is smooth muscle, cardiac muscle, and glands

****The viscero-somatic pathway sends fibers from the NTS to the ____, which innervate the larynx and pharynx and play a role in deglutition and cough****
^** Remember SNS is skeletal muscle

7, 9, and 10, Nucleus Tractus Solitarious (NTS aka Solitary Nucleus)

Anterior 2/3rds, posterior 1/3rd

Dorsal motor nucleus of X

Nucleus Ambiguus


Name the pathway for the Carotid Body reflex

Stimulus? -> Sinocarotid Nerve ___? -> ___ -> ___ -> ____ Nucleus? -> ____ -> Response?

Increase CO2 -> Vagus Nerve -> NTS -> Reticular Formation -> Phrenic Nucleus -> Diaphragm -> Increased ventilation


Name the pathway for the Carotid sinus reflex

Stimulus? -> Sinocarotid Nerve? -> ___ -> ___ -> ____ Nucleus? -> ____ -> Response?

Increased blood pressure -> Vagus nerve -> NTS -> Reticular Formation -> Dorsal Motor Nucleus -> Cardiac Branches of Vagus -> Decreased Cardiac Contraction


********Name the pathway for the Gag reflex

Stimulus? -> ____ Nerve? -> ___ -> ___ -> ____-> ____ -> Response?***************

Touching pharyngeal mucosa -> Glossopharyngeal nerve -> NTS -> Reticular formation -> Nucleus Ambiguss -> Pharyngeal branch of Vagus Nerve -> Gagging


So once again, visceral reflex fibers primarily enter at ___ levels



The LER (Laryngeal Expiration Reflex) occurs when there is a stimulus to the ____ and then the ____ nerve goes to the ____ (and adjacent LER pattern generator and associated brainstem and spinal cord nuclei) and then to the ___ (name both of them) which travels to two separate places

1) ____ -> ____ nerve -> ___ control -> ___ response

2) ____ -> ___ nerves -> ___ muscle -> Closure of the ___ and ___ -> ___ response

Unlike a voluntary cough, the LER is different because it is a cough WITHOUT ____ and is therefore a airway protective cough

Laryngeal mucosa, IbSLR, NTS, Reticular formation (LRST and LVST)

1) Nucleus ambiguus -> RLN -> Glottal control -> Expiratory cough Epoch and airway cleaning

2) Medial Motor Cell Column -> Thoracoabdominal -> External Abdominal Oblique -> Abdominal and pelvic sphincters -> Expiratory cough

Inhalation (inspiration)



As the bladder fills with urine (increased volume and increased bladder tone) there are stretch receptors in the bladder wall that become activated. These are the primary afferent fibers that send impulses through the dorsal root to the ____ nucleus located in the sacral segments S2-S4. Then, interneurons convey the stimulus to the ___ nucleus at S2-S4 and then efferent fibers from this nucleus stimulate the bladder to ___


The bladder reflex is under the control of the ___ tract *******

VAN (Visceral Afferent Nucleus), SAN (Sacral Autonomic Nucleus), empty (void) Via bladder muscles contracting

LRST (Lateral Reticulospinal Tract)


*********** WILL BE TESTED ON SO KNOW THIS*********

Transection of the spinal cord above S2 disrupts the ____ tract to the ___ nucleus, and the patient is therefore unable to voluntarily void their bladder (urinary retention occurs)

^** After ____, the bladder reflex man return without voluntary control and the patient will have automatic reflex voiding or a ___ bladder

If a lesion to the dorsal roots of S2-S4 or dorsal funiculi of S2-S4 occurs, ___ results and this causes a ___ bladder and increased bladder capacity; but voluntary voiding is still possible, but incomplete

*********** WILL BE TESTED ON SO KNOW THIS*********

Transection of the spinal cord above S2 disrupts the ____ tract to the ___ nucleus, and the patient is therefore unable to voluntarily void their bladder (urinary retention occurs)

^** After ____, the bladder reflex man return without voluntary control and the patient will have automatic reflex voiding or a ___ bladder

If a lesion to the dorsal roots of S2-S4 or dorsal funiculi of S2-S4 occurs, ___ results and this causes a ___ bladder and increased bladder capacity; but voluntary voiding is still possible, but incomplete LRST, SAN

Spinal Shock, reflex

Atonic Bladder, flaccid


So for Visceral pain in the head, the primary neuron is located in the ___ and conveyed via the ___ where is synapses in the ____, travels via the ___ fibers to the centromedian and hypothalamus

GVA sensory ganglia, Solitary tract, NTS, Solitaro-hypothalamic fibers


**************If you cut the dorsal roots, the effect on muscle tone is that it ____ muscle tone***************

Because muscle tone is maintained by a reflex arc, so if you cut the input you lose the output



If the ___ is destroyed, it's tracts along with associated motor tracts in the lateral funiculus will result in spastic paralysis, hyperreflexia, hypertonia, babinskis sign, clonus, and disuse atrophy

It will therefore present with a ____ paralysis below the level of the lesion (since it has already decussated once it becomes the LCST)

The CST are ___ motor neurons

LCST (Lateral Croticospinal Tract)




If a Unilateral ___ lesion occurs above the level of S2, it cant send its fibers to the SAN and the patient presents with the inability to voluntarily void their bladder (aka urine retention)

After Spinal shock, reflex bladder can occur

LRST (Lateral reticulospinal tract)


Unilateral lesion of the ___ in the anterior region results in ____ loss of pain and temp sensation two sensory dermatome segments below the level of the lesion

*****************If the lesion is at the level of T6 on the right side, youd get loss of pain and temp sensation from ___ on the ___ side*************

LSTT (Lateral SPinothalamic tract), contralateral

T8, left



The decussating fibers in the fast pain pathways occur in the ____ and destruction results in a ____ loss of pain and temp sensations to the ___ extremities

Anterior White Commissure, Bilateral, Upper


In order to relieve intractable pain, a surgeon can perform a ____, where they cut out the anterolateral quadrant of the cord and use the ___ ligament as a landmark between the LSTT (anterior) and corticospinal fibers (posterior)

In order to relieve anxiety and emotional components associated with intractable pain, a ____ can be performed where they remove the prefrontal lobes surgically (but they are insensitive to pain)

Anterolateral cordotomy, Denticulate



************ WILL BE TESTED ON**********

A meningovascular inflammation of the blood vessels as they pierce through the pia is called ____ and it occurs while piercing the pia at the junction of the ___ and ____ (which are the two structures effected via bilateral ischemic necrosis at the level)

Signs include "____ pains" down the extremities due to the irritation of epicritic Type A pain fibers in the dorsal roots

Involvement of the dorsal roots in the sacral region results in ____

************ ___-based gait with ___ of the feet should IMMEDIATELY tip you off as Tabes Dorsalis ******** since the loss of proprioception from the lower extremities causes this

One can perform the ____ test for this and Argyll-Robertson pupils are present

Tabes dorsalis, Dorsal rootlets and Posterior Columns


Atonic Bladder

Broad, Slapping



***** ALS (Amyotrophic Lateral Sclerosis) aka Lou Gehrigs disease is both an UMN and LMN disease and the most important aspect is that there are NO ___ deficits *******



The spinal cord has 3 modifications in shape, the cervical enlargement (C4-T1) associated with brachial plexus to upper extremities, lumbosacral enlargement (L2-S3) associated with lumbosacral plexus to lower extremities, and the ***********************conus medulalris at the level of ____ interspace and these nerve rootlets emerge from the spinal cord segments that innervate the lower sacral dermatomes including the ____ and ___

LV1-2, bladder, rectum


For the spinal nerves and their vertebral foramen that they exit, C1-C7 exit ___ there vertebra and C8 exists at CV7-TV1, and therefore T1 down exists ___ their vertebra

The Conus medullaris goes from ___-___ and Cauda Equina goes from ___-___

above, below

L1-L2, L2-Sacrum


***********Name the sensory dermatome's spinal cord segment

1) Shoulders
2) Thumb (Pollicis)
3) Little finger/Elbow
4) Nipple
5) Umbilicus
6) Inguinal region
7) Big toe (Hallucis)
8) Little toe
9) Perianal region

1) C4
2) C6
3) T1 (Although we were taught C8)
4) T4
5) T10
6) L1
7) L5
8) S1
9) S5


*************Name the motor dermatome's spinal cord segment

1) Biceps Brachii M.
2) Brachialis M.
3) Triceps Brachii M.
4) Muscles of Hand
5) Quadriceps Femoris M.
6) Gastrocnemius M.
7) Scapular
8) Epigastric
9) Abdominal
10) Cremasteric
11) Superficial Anal

1) C5-C6
2) C6-C7
3) C6-C8
4) C8-T1
5) L2-L4
6) L5-S2
7) C5-T1
9) T8-T12
10) L1-L2
11) S4- Co1


Central cord syndrome can result from disruption of the ___ artery

*******************The ___ artery arises from the left inferior intercostal or superior lumbar arteries and can contribute to the ___ artery. It is the MAJOR supply to the ___ of the spinal cord and can be compromised secondary to a throacolumbar fracture or surgical repair of an _____******************

Anterior spinal artery

Greater anterior artery of Adamkiewicz, anterior spinal artery, inferior 2/3rds, AAA (Abdominal aortic aneurysm)


***The most frequent areas of ischemic necrosis of the spinal cord include the C___, T__, and L___ regions*****

C2-C3, T1-T4, L1

^Notice it is the upper regions****


Muscle tone and proprioception is controlled by the __ pathway influenced by descending information

************* Increased gamma motor activity causes a corresponding ___ in muscle tone (aka ____), and an associated reflex called ____

Decreased gamma motor activity results in a ___ of muscle tone (aka ____) and an associated reflex called _____

Gamma efferent

Increased (Hypertonia), Hyperreflexia

Decreased (Hypotonia), Hyporeflexia


Name the nucleus based on the location

1) Posterolateral tip of the dorsal horn at all spinal levels
2) Mid portion of the dorsal horn
3) Base of the dorsal horn from C8--L2
4) T1-L2 and S2-S4
5) Between the dorsal and ventral horns at all spinal levels
6) Medial part of the ventral horn, at all spinal levels
7) Lateral part of ventral horn in the regions of the cervical and lumbosacral enlargements
8) C3-C5 (a subdivision of the MMCC)
9) C1-C6 (continuous with the nucleus ambiguus in the medulla)
10) Lateral horn from T1-L2
11) Lateral horn from S2-S4

1) Substantia Gelatinosa (SG)
2) Nucleus Proprius (NP)
3) Nucleus Dorsalis
4) Visceral Afferent Nucleus (VAN)
5) Intermediate gray (IG)
6) Medial Motor Cell Column (MMCC)
7) Lateral Motor Cell Column (LMCC)
8) Phrenic Nucleus
9) Spinal Accessory Nucleus
10) Intermediolateral Nucleus
11) Sacral Autonomic Nucleus (SAN)


Name the function for each nucleus

1) Substantia Gelatinosa (SG)
2) Nucleus Proprius (NP)
3) Nucleus Dorsalis
4) Visceral Afferent Nucleus (VAN)
5) Intermediate gray (IG)

Name the innervation

6) Medial Motor Cell Column (MMCC)
7) Lateral Motor Cell Column (LMCC)
8) Phrenic Nucleus
9) Spinal Accessory Nucleus
10) Intermediolateral Nucleus
11) Sacral Autonomic Nucleus (SAN)

1) Pain/temp
2) Pain/temp
3) Unconscious proprioception
4) Visceral sensory integration and reflex center
5) Sensorimotor integration center

6) Axial musculature
7) Muscles of extremities
8) Respiratory Diaphragm
9) SCM and traps
10) Preganglionic sympathetic fibers to visceral structures
11) Preganglionic parasympathetic fibers to bowel and bladder


Name where the nucleus sends fibers to

1) Substantia Gelatinosa (SG)
2) Nucleus Proprius (NP)
3) Nucleus Dorsalis
4) Visceral Afferent Nucleus (VAN)
5) Intermediate gray (IG)

1) Lateral Spinothalamic tract (LSTT)
2) Fasciculus proprius
3) Dorsal Spinocerebellar tract (DSCT)
4) IG, Ventral horn, hypothalamus via fasciculus proprius
5) Ventral horn