Quizlet - Final Flashcards
(250 cards)
1
Q
In the spinal cord, the white matter is broadly categorized into what three bundles (per side)?
A
- Dorsal funiculus
- Lateral funiculus
- Ventral funiculus
2
Q
In the spinal cord, the gray matter areas dorsal and ventral to the central canal are called what?
A
- Dorsal Gray commisure
- Ventral Gray commisure
3
Q
The gray matter of the spinal cord is divided into how many laminae? In which zone are each lamina in the gray matter?
A
Ten in total.
Dorsal horn –> laminae I - VI
Ventral horn –> laminae VII - IX
Central gray –> lamina X
4
Q
Prior to C7, each spinal nerve runs (cranial/caudal) to its corresponding vertebra. After the C7 , the corresponding nerves run (cranial/caudal) to their vertebrae.
A
Cranial before C7
Caudal after C7
5
Q
The spinal cord ends with which vertebral segment?
A
L6
6
Q
What leads to the formation of the cauda equina?
A
The vertebrae grow faster than the spinal cord, but still maintain their connection, resulting in a stretching of nerve fibers.
7
Q
Which nervous plexus display the greatest extent of cauda equina?
A
Lumbosacral plexus
8
Q
T/F: The amount of white matter in a spinal cord segment increases as one progresses caudally.
A
FALSE
It decreases as one progresses caudally.
9
Q
What are the names of the two ventral gray matter enlargements (intumescence), where are they located, and what is their purpose?
A
Cervical (or brachial) enlargement
From C7 –> T2
Provide motor neurons for the forelimbs
Lumbosacral enlargement
From L4 –> S1
Provide motor neurons for the hindlimbs
10
Q
The intermediate zone of the spinal gray matter is responsible for what kind of control?
A
Autonomic
11
Q
What is a dermatome? What is a cutaneous area? How are these two different?
A
A dermatome is the skin area innervated by one spinal nerve and all of its peripheral branches. There is much overlap between dermatomes.
A cutaneous area is a zone of skin supplied by nerves of similar function.
A dermatome is one nerve which may have multiple functions. A cutaneous area is multiple nerves with one function.
12
Q
T/F: In the Withdrawal Reflex test the foot being stimulated retracts, and the contralateral foot extends.
A
TRUE
13
Q
When performing the Withdrawal Reflex test, what are the three desired reactions and what does each one indicate?
A
1.) Foot receiving stimulus withdraws.
This indicates the reflex response is working and shows the ipsilateral interneurons are functioning properly.
2.) Contralateral foot extends.
This indicates the reflex response is working and shows the contralateral interneurons are functioning properly.
3.) Head turns to observe stimulus.
This indicates the dog’s conscious reception of the signal and shows that the ascending pathways are functioning properly.
14
Q
T/F: On presynaptic neuron may synapse with a few to many thousand postsynaptic neurons.
A
TRUE
15
Q
T/F: One presynaptic neuron may not have multiple synapses with a single postsynaptic neuron.
A
FALSE
16
Q
Much of the sensory information sent to the brain is never perceived. For what two reasons is this true?
A
- Inhibition in the cortical pathway prevents perception at that moment
- Pathway to the cortex doesn’t exist, therefor there is no way for signal to be perceived
17
Q
What is the term to describe the grouping of motor neurons which spans multiple contiguous spinal segments?
A
Motor neuron pool
18
Q
T/F: Collateral distribution of one primary afferent sensory neuron includes many segments both rostral and caudal to the segment of entry.
A
TRUE
19
Q
Motor neuron pools are organized in the ventral horn of the spinal cord. What is the manner of their organization? For instance, where would the nerve cell bodies be located for the brachial zone as compared to the antebrachial zone?
A
More proximal projections are located more medially in the ventral horn, and distal projections are more lateral.
For instance, the cell bodies for nerves of the brachial zone will be closer to the central canal (more medial) than those for the antebrachial zone.
20
Q
Define: Nociception
A
A reflex; a reaction that occurs without nerves reaching the brain for processing.
21
Q
Define: Pain response
A
A conscious reaction to a painful stimulus.
22
Q
Describe the differences between nociception and pain perception.
A
- Often difficult to differentiate
- Important for lesion site determination
- Nociception circuit does not enter brain and is therefore not a conscious response
- Pain perception circuits do enter the brain and are a conscious response
EXAMPLES
Nociception –> withdraw limb; contralateral extension
Pain perception –> turns head; growls; whines
23
Q
Which portion of the nervous system has the better neuron-regenerative capacities?
A
PNS
Peripheral Nervous System
24
Q
In the case of spinal cord injury, where do signs of the injury manifest?
A
Signs appear level to, or caudal of, the site of the spinal cord injury.
25
What are some clinical signs of spinal cord injury?
- Hyperreflexia/Areflexia
- Muscle hypertonia/hypotonia
- Loss or reduction of pain response
- Muscle denervation
26
In the case of severe injury to the brachial enlargement, what would be the state of the Lower Motor Neurons (forelimb)? What of the Upper Motor Neurons (hindlimb)?
FORELIMBS (LMN)
- Paralysis
- Areflexia
- Atonia
- Denervation atrophy
- Sensory disturbance
HINDLIMBS (UMN)
- Paralysis
- Hyperreflexia
- Hypertonia
- Diuse atrophy
- Sensory disturbance
27
In the case of severe injury to the thoracolumbar region, what would be the state of the Lower Motor Neurons (forelimb)? What of the Upper Motor Neurons (hindlimb)?
FORELIMBS (LMN)
- Mostly normal
- Schiff-Sherrington (don't worry about it)
HINDLIMBS (UMN)
- Paralysis
- Hyperreflexia
- Hypertonia
- Disuse atrophy
- Sensory disturbance
28
In the case of severe injury to the lumbosacral enlargement, what would be the state of the Lower Motor Neurons (forelimb)? What of the Upper Motor Neurons (hindlimb)?
FORELIMBS (LMN)
-Normal
HINDLIMBS (UMN)
- Paralysis
- Areflexia
- Atonia
- Denervation atrophy
- Sensory disturbance
29
Name one specific type of reflex test that can be used to determine lesion location.
Cutaneous trunci reflex test.
30
Define: Exteroceptors
Receptors that respond to external stimuli impinging on the skin.
31
Define: Proprioceptors
Receptors that signal changes in position that occur during movement. They are found in muscles, joints, ligaments, tendons, and the vestibular system.
32
Define: Interoceptors
Receptors that detect changes of a chemical or mechanical nature in the viscera of the body wall.
33
What are some practical uses for rapidly-adapting receptors? What about slowly-adapting receptors?
Rapidly-adapting:
- Transient events such as stimulus contact
- High frequency events like vibration
Slowly-adapting:
-Maintained events such as pressure
34
Which type of adapting receptor shows a negative spike in receptor potential when a stimulus ceases?
Rapidly-adapting receptors
35
When conducting impulses, it can be seen that there are two peaks that occur: an A peak, and a C peak. What types of neurons are responsible for the A peak, and what types of neurons are responsible for the C peak?
A peak --> large number of myelinated neurons
| C peak --> small, unmyelinated neurons
36
Using the roman numeral schema, what group(s) of nerves are responsible for proprioception? Which are responsible for pain and temperature?
Proprioception --> Groups I and II
| Pain and Temperature --> Groups III and IV
37
T/F: The majority of touch is represented by A-delta and C fibers.
FALSE
| Touch is represented by A-delta and C fibers, but the majority of touch receptors are supplied by A-beta afferents.
38
Local anesthetics affect which size nerve fibers most rapidly and for the longest duration?
Small diameter fibers
39
For pacinian corpuscles, what types of fibers are involved? Where are they located? What are they sensitive to?
- Rapidly-adapting A-beta fibers
- Located primarily in SQ
- Sensitive to minimal gingival or skin distortion
40
For Meissner's corpuscles, what types of fibers are involved? Where are they located? What are they sensitive to?
- Rapidly-adapting A-beta fibers
- Located superficially in skin of hand
- Sensitive to skin distortion (less so than pacinian corpuscles).
41
For Merkel cells, what types of fibers are involved? Where are they located? What are they sensitive to?
- Slowly-adapting fibers
- Located in hairy skin of face, skin of hands
- Sensitive to gingival or skin distortion
42
What is another term for pain receptors?
Nociceptors
43
Name some of the detail discrimination that is involved in the dorsal column system.
- Direction and frequency of movement of tactile stimuli
- Shape, texture, and location of tactile stimuli
- Positional information from forelimb and hindlimb
44
What two fasciculi make up the lemniscal tracts, and from where does each transmit signals?
Fasciculus gracilis --> receives input from sacral, lumbar, and lower thoracic roots
Fasciculus cuneatus --> receives input from upper trunk, neck, and arm roots
45
Axons from the gracile and cuneate nuclei cross the ___________ fibers and collect to form the ________________.
...cross the Internal Arcuate fibers...
| ...collect to form the Medial Lemniscus.
46
Where does the medial lemniscus project to?
Ventrocaudal lateral nucleus (VCL)
47
Thalamocortical axons from the VCL terminate in which two places?
- Primary somatic sensory cortex SI
| - Secondary somatic sensory cortex SII
48
Which axons form the spinocerebellar tracts?
Axons of the dorsal horn neurons
49
What is the purpose of the spinocerebellar systems?
They convey proprioceptive information to the cerebellum.
50
Primary afferents synapse where?
In spinal cord gray matter.
51
What types of information are conveyed in the ventral ascending pathways?
- Crude touch
- Pain
- Temperature
52
Describe the fibers that synapse in the dorsal horn.
- Small diameter
- Slow conducting
- Peripheral afferent A-delta and C fibers
53
Where do dorsal horn neurons go to collect as the spinothalamic and spinoreticular tracts?
To the contralateral central funiculus
54
What, specifically, is the spinothalamic tract involved in?
Location and intensity of painful stimuli
55
What, specifically, is the spinoreticular tract involved in?
Affective qualities of painful stimuli
56
In what two areas can nerves be found within teeth?
- Pulp
| - Dentin tubules
57
Dramatic changes in the fluid flow within dentin tubules can be very painful. Name some stimuli that could affect fluid flow.
- Mechanical stimuli
- Evaporation
- Sugar solutions
- Cold
58
What are the three nuclei of the Trigeminal system, and what is each responsible for?
Chief Sensory nucleus
-Receives touch input from fave and oral cavity
Spinal nucleus
- Oralis: oral cavity reflexes
- Interpolaris: head and oral cavity; tactile reflexes
- Caudalis: pain and temperature
Mesencephalic nucleus
-Proprioception from muscles of mastication
59
Axons from which of the Trigeminal nuclei cross, join the medial lemniscus, and project to the ventrocaudal medial nucleus (VCM)?
- Chief Sensory nucleus
- Oralis (of the Spinal nucleus)
- Interpolaris (of the Spinal nucleus)
60
Axons from which of the Trigeminal nuclei cross, join the spinothalamic tract, and project to the intralaminar nucleus (IL)?
Caudalis (of the Spinal nucleus)
61
Name some of the separate representations the SI is able to process.
- Cutaneous information
- Deep receptors and proprioception
- Muscle afferent information
62
T/F: Body regions with greater receptor density or greater behavioral relevance have larger cortical representations.
TRUE
63
The SI contains a complete body map. Describe the organization of the body on the SI.
Face laterally --> Hindlimb medially
64
Define: Pain
A sensory perception of a nociceptive event.
65
Describe the difference between acute and chronic pain.
Acute pain --> brief, elicits avoidance
| Chronic pain --> long-term, produces depression
66
Describe the difference between superficial pain and deep pain.
Superficial --> sharp; pricking; "first"
| Deep --> aching; burning; "second"
67
Describe what is entailed in the sensory-discriminative dimension of pain.
- Where is the stimulus?
- What kind of stimulus?
- How fast is the stimulus being applied?
68
Describe what is entailed in the motivational-affective dimension of pain.
- How can the stimulus be avoided?
| - How severe is the injury?
69
T/F: First (superficial) pain is fast, and signaled by unmyelinated C nociceptors.
FALSE
First (superficial, fast) and second (deep, slow)
pain are signaled by myelinated A delta and
unmyelinated C nociceptor fibers, respectively.
70
Name some factors that would affect one's pain threshold.
- Stress
- Anxiety
- Chronic conditions
71
What is the difference between one's pain-detection threshold and one's pain-tolerance threshold? What is the term for the area in between?
Pain-detection threshold --> point at which one consciously notices pain
Pain-tolerance threshold --> the maximum painful stimulus one will willingly tolerate
Range between these two terms is deemed the pain-sensitivity range.
72
Nociceptors are classified as "free nerve endings". Why? Are all free nerve endings nociceptors?
Termed "free nerve endings" based on their unmyelinated structure and staining characteristics in light microscopy.
No. In humans and animals, free nerve endings also subserve thermal sensations and non-perceived visceral functions.
73
Name some of the stimuli nociceptors are capable of responding to.
- Strong mechanical pressure
- Heat
- Excessive cold
- Electrical
- Chemical substances
74
T/F: Nociceptors do not normally respond to non-noxious levels of stimulation.
TRUE
75
Compared to non-nociceptors, nociceptors have (high/low) activation thresholds and (increase/decrease) their response magnitude throughout the noxious range.
High
| Increase
76
Nociceptive fibers mostly terminate in what portion of the spinal cord?
In the superficial layers of the dorsal horn
77
Describe the differences between ipsilateral, contralateral, and bilateral pathways.
Ipsilateral --> fiber stays on the same side (left/right) of the spinal column
Contralateral --> fiber crosses over to the other side (left/right) of the spinal column
Bilateral --> fiber bifrucates and is apart of both sides (left/right) of the spinal column
78
Describe some properties of spinal nociceptive pathways.
- Deep
- Diffuse
- Redundant through the white matter
- Difficult to eliminate surgically
79
What is the size of the axons involved in the spinal nociceptive pathways?
Small-diameter axons
80
Spinal nociceptive pathways can be divided into two groups, one subserving the sensory-discriminative dimension of pain and the other subserving the motivational-affective dimension. Which is which?
Lateral group --> sensory-discriminative
| Medial group --> motivational-affective
81
Describe the pathway for an ipsilateral ascending pathway.
```
Primary afferent neuron enters dorsal horn of spinal cord -->
1st relay nucleus -->
2nd order neuron -->
2nd relay nucleus -->
3rd order neuron -->
Contralateral thalamus (aka 3rd relay nucleus) -->
4th order neuron -->
Contralateral cerebral cortex
```
82
Between an A-beta fiber and a C fiber in the dorsal horn, which acts as a stimulator and which acts as an inhibitor?
A-beta --> inhibitor
| C --> stimulator
83
Describe the purpose of the tactile placing response (which is NOT a reflex).
- Requires intact cortex and consciousness
| - Tests non-nociceptive conscious proprioception pathways
84
T/F: There is not a correlation between a loss of reflex and a loss of pain perception.
TRUE
85
Name some conditions that can cause loss of the withdrawal reflex.
- Damage to sensory innervation
- Damage to the spinal cord
- Damage to motor innervation to flexor muscles
- Blockage of neuromuscular transmission
86
Name some effects chronic pain can have on pathways, sensitivity, hormonal balance, etc.
- Allodynia
- Hyperalgesia
- Stress, anxiety, depression
- Increase in cortisol and catecholamines
- Tachycardia
- Decreased motility
- Delayed healing
87
What type of tissue does the autonomic nervous system (ANS) supply? Give some examples.
Visceral tissue
- smooth muscle
- cardiac muscle
- glands
88
From what region of the spinal cord does the sympathetic region of the ANS originate? What of the parasympathetic region?
Sympathetic --> thoracolumbar
| Parasympathetic --> craniosacral
89
What systems is the sympathethic nervous system related to? Parasympathetic?
Sympathetic --> distribution to the entire body
Parasympathetic --> supplies only visceral cavities, head, and genitalia. Does NOT supply the skin or limbs.
90
Sympathetics travel via what nerve bundle?
Sympathetic trunk
91
The parasympathetic system originates from which four cranial nerve nuclei?
- Oculomotor (CN III)
- Facial (VII)
- Glossopharyngeal (IX)
- Vagus (X)
92
What does the sympathetic ANS respond to? How does it respond?
Responds to stress, fight/flight, or strenuous exercise.
- Decreases visceral organ motility
- Decreases sweating
- Increases blood pressure
- Increases cardiac function
- Dilates bronchii
- Dilates pupils
93
What types of neurotransmitters are released by preganglionic neurons? What are the types of receptors?
Acetylcholine (ACh) is released into Nicotinic receptors
94
Describe the sympathetic postganglionic release of neurotransmitter.
- They're releases from many varicosities along the length of the axon.
- They diffuse through adjacent smooth muscle cells via gap junctions.
95
Describe the three types of Beta receptors.
Beta-1 --> excitatory in the heart
Beta-2 --> inhibitory to smooth muscle
Beta-3 --> lipolysis
96
Name three neurotransmitters commonly released by sympathetic postganglionic neurons.
- Norepinephrine
- Epinephrine
- Dopamine
97
What neurotransmitter is most commonly released by parasympathetic postganglionic neurons?
Acetylcholine (ACh)
98
T/F: Muscarinic receptors are generally inhibitory.
FALSE
99
What chemical can be used to block the coupling of parasympathetic postganglionic cells to target cells?
Atropine
100
Describe the enteric nervous system (ENS).
- Intrinsic mucosal neurons that can operate independently from the CNS
- Regulates the inner circular smooth muscle layer with the outer longitudinal layer
101
What type of fibers connect two enteric plexi?
Interganglionic fibers
102
Name some intrinsic reflexes that are triggered in response to distention.
- Peristalsis
- Segmentation-mixing movements
- Tonic contraction of sphincters
103
T/F: 90% of visceral sensory afferents are unmyelinated.
TRUE
104
Compared to skin, there is a (high/low) peripheral receptor density in visceral tissue.
Low
105
For visceral sensory afferents, where are the majority of the cell bodies located?
Dorsal root ganglia
106
What two types of stimuli are visceral afferent terminals positioned to respond to?
- Mechanical
| - Chemical
107
Afferents in sympathetic nerve trunks can lead to what? What of afferents in parasympathetic nerve trunks?
Sympathetic --> perceived visceral pain
| Parasympathetic --> performing unperceived regulatory functions
108
Describe the pathway of visceral afferent relays in the brain.
```
Nucleus of tractus solitarius (NTS) -->
Parabrachial nucleus -->
Hypothalamus -->
Midline thalamic nuclei -->
Limic nuclei
```
109
Describe visceral pain.
- Poorly localized
- Can be due to a blockage in a hollow organ
- Can be due to a stretching in a solid organ
- Often difficult to ameliorate
110
What is "referred pain" and what causes it?
"Referred pain" is pain located somewhere other than the site of the negative stimulus.
Can be due to overlying serosal inflammation, or viscerosomatic convergence.
EX: when a person is having a heart attack and their left arm becomes painful.
111
Describe the carotid sinus reflex.
A very important reflex for the control of systemic blood pressure, the carotid sinus reflex involves the integration of baroreceptors in the carotid sinus and both divisions of the ANS.
112
Describe the micturition reflex.
The process of voiding the bladder, which can be voluntary or involuntary, requires the integration of neurons from all parts of the nervous system (sympathetic, parasympathetic, and somatic).
113
The retina develops as an outgrowth of which major brain division?
Diencephalon
114
T/F: The retina is considered part of the PNS.
FALSE
| CNS
115
Name the layers of the retina from inside (side of light entering) to outside (where signal is an impulse).
```
Nerve fiber layer -->
Ganglion layer -->
Inner plexiform layer -->
Inner nuclear layer -->
Outer plexiform layer -->
Outer nuclear layer -->
Receptor layer
```
116
Between rods and cones, which is more sensitive to light?
Rods
117
Describe the two different pathways for optic tracts.
Optic tract -->
Lateral Geniculate Nucleus (LGN) -->
VI (primary visual cortex)
Optic tract -->
LGN -->
Brachium of rostral colliculus -->
Rostral colliculus and pretectal area
118
What is the main pathway linking center for coordinated control of eye movement? (there is one in for each eye)
Medial longitudinal fasciculus
119
The medial longitudinal fasciculus include the motor nuclei for which cranial nerves?
- Oculomotor (CN III)
- Trochlear (CN IV)
- Abducens (CN VI)
120
What mediates the consensual light reflex?
The caudal commissure
121
Name three important functions of the Oculomotor nerve (CN III).
- Converges the eyes through co-contraction of the medial rectus muscles.
- Rounds the lens via contraction of the ciliary muscles.
- Constricts the pupils to sharpen acuity.
122
What is the auditory system responsible for?
Responsible for the detection and analysis of air-borne vibrations; transmitting this analysis to the brain as sounds.
123
What is the vestibular system responsible for?
Responsible for sensing the position of the head; transmitting this analysis to the brain for feedback on balance.
124
Name the three bones of the middle ear in order of an incoming sound wave.
Malleus -->
Incus -->
Stapes
125
T/F: Incoming signals enter the cochlea through the round window and terminate through the oval window after completing its circuit.
FALSE
Incoming signals enter the cochlea through the OVAL window and terminate through the ROUND window after completing its circuit.
126
Describe each of the three layers of the tympanic membrane (the ear drum).
- Outer layer: continuous with the skin of the external meatus
- Middle layer: sheets of collagenous connective tissue
- Inner layer: continuous with the lining of the middle ear
127
What additional factor do animals have in the ear canal that makes them more susceptible to chronic ear infections?
The auditory canal of dogs, for instance, is L-shaped. This makes it difficult to medicate infections near the ear drum.
128
What muscle is responsible for the malleus? What nerve innervates this muscle?
Tensor tympani
| innervated by the Mandibular division of the Trigeminal nerve (CN V)
129
What muscle is responsible for the stapes? What nerve innervates this muscle?
Stapedius
| innervated by the Facial nerve (CN VII)
130
What two openings maintain pressure in the middle ear?
- Auditory canal
| - Eustachian tube
131
Describe the process of sound entering the ear through its integration in the cochlea.
Sound enters pinna and travels through auditory canal -->
Sounds hit tympanic membrane -->
Tympanic membrane hits ossicles -->
Ossicles hit the oval window and send vibrations through the cochlea -->
Sounds travel through cochlea and exit round window
132
What is a difference between the eustachian tubes of infants and adults?
Infant's tube are more curved and, therefore, more difficult for transmission of fluids/pressure.
133
What fluid fills the membranous labyrinth of the inner ear? What fluid surrounds it?
Fills --> Endolymph
| Surrounds --> Perilymph
134
T/F: The fluids in the inner ear have similar ionic concentrations as respective cellular fluids (extracellular = high Na, low K; intracellular = low Na, high K).
TRUE
135
Name the 2 major divisions of the bony labyrinth, and which system each is apart of.
Vestibule and Semicircular canals --> Vestibular
Cochlea --> Auditory
136
Name the 3 major divisions of the membranous labyrinth.
- Semicircular canals
- Sacule, utricle (vestibule)
- Cochlear duct (cochlea)
137
What is the modiolus and what is its purpose?
The modiolus is a hollow bony canal through the center of the cochlea through which the cochlear nerve enters at the basal turn and travels.
138
What is the osseous spiral lamina, and what is its purpose?
The osseus spiral lamina is a hollow shelf that coils around the modiolus like the threads of a screw.
139
The spiral ganglion contains the origin of which nerve within the modiolus?
Auditory nerve (CN VIII)
140
For each of the following cavities, what kind of fluid runs through them?
- Scala Vestibuli
- Scala Media
- Scala Tympani
- Scala Vestibuli --> Perilymph
- Scala Media --> Endolymph
- Scala Tympani --> Perilymph
141
T/F: Reissner's membrane is very thick.
FALSE
| Reissner's membrane is only 2 cells thick.
142
The basilar membrane, a fibrous ribbon that spans the whole cochlea, is made of bundles of microfilaments. This is essential for what property of sound?
Essential for frequency (pitch) resolution
143
There are two types of hair cells, Inner and Outer. How many rows are there of each one, and what is each type responsible for?
1 row of Inner hair cells --> sensory transduction
3 rows of outer hair cells --> mechanical processes which influence frequency tuning in the cochlea
144
Both types of hair cells are locked at their apical ends into a ridged matrix called the...?
Reticular lamina
145
What nerve innervate the hair cells (both types)?
Peripheral processes of the Cochlear nerve (CN VIII)
146
Which end of the cochlea (base or apex) is more sensitive to low frequency sounds? Which is more sensitive to high frequency?
Base --> high frequency
| Apex --> low frequency
147
Describe how the hammering of the stapes on the oval window results in release of nerves discharges from hair cells.
Hammering on oval window sends vibrations through cochlea -->
Tectorial membrane is gelatinous substance attached to hair cells that moves along with vibrations -->
Movement of tectorial membrane creates shearing forces on hair cells -->
Depending on direction of forces, hair cells either depolarize or hyperpolarize
148
Hair cells have two different types of "hairs". What are they, and what are their major differences?
Stereocilia --> multiple, shorter "hairs"
| Kinocilium --> a single, long "hair"
149
What direction do the shearing forces have to be for hair cells to depolarize? To hyperpolarize?
Towards kinocilium --> depolarize
| Away from kinocilium --> hyperpolarize
150
The Vestibulocochlear nerve (CN VIII) passes through which foramina of the skull?
Internal auditory meatus (IAM)
151
Name the three major causes of damage to hair cells, and give an example of each.
- Disease: Meiniere's disease
- Oto-toxicity: antibiotic intoxication
- Sound: gun shots
152
In the central auditory pathway, what kind of organization can be found on every level of processing?
Tonotopic organization
153
In the central auditory pathway, where do all signals converge, and where do they then go?
With the lateral lemniscus tract they converge to go to the inferior colliculus at midbrain level.
154
Some some contributions to binaural interactions provided by the superior olive.
- Sound localization
| - Diagnostic characteristics
155
Name one nervous structure (and its location) that serves as a mechanism to filter out unnecessary noise.
Medial geniculate body in the auditory division of the thalamus
156
What are the two otolithic organs of the inner ear?
- Utricle
| - Saccule
157
Describe the function of the otolithic organs.
- Both consist of a flat sheet of hair cells with a specialized membrane (otolithic membrane) balanced on top.
- This sheet is weighted with calcium carbonate crystals.
- During linear acceleration, the weight of the crystals cause the membrane to lag behind the movement and create a shearing force.
- The shearing force, same as in the cochlea, moves the "hairs" of the hair cells and transducts signals through the vestibular nerve.
158
Describe the lateral vestibulo-spinal tract (LVST).
- Vestibular nerve fibers which innervate the otolithic organs terminate on cells in the lateral vestibular nucleus in the medulla.
- The axons forms a major tract which descends to the spinal cord LVST
- It acts to excite/facilitate extensor motorneurons
159
How many semicircular canals are there, and what are their directionalities?
3 total: 1 horizontal and 2 vertical
160
Where are the cilia located in the semicircular canals?
They're embedded in a gelatinous membrane called the cupula, which is located in a small swelling of the canal where it meets the ampule.
161
What do the semicircular canals detect?
Angular acceleration
162
What is the most important function of the semicircular canals?
To help maintain constant eye orientation in spite of movements of the head.
163
What is the name of the fiber tract that connects the vestibular nuclei (in the brainstem) to CNs III, IV, and VI?
Medial longitudinal fasciculus
164
If one were to turn one's head to the left, describe the vestibular actions required to keep one's eyes fixed on a single position.
TURNING LEFT!!
-Activates L-semicircular canal
-Increases firing in the L-vestibular nerve
-Increases input into the L-vestibular nucleus
-Medial Longitudinal Fasciculus (MLF) connections activate motor neurons innervating the R-lateral rectus muscle in the right eye
-Right eye turns right
MLF connections activate motorneurons innervating the L-medial rectus muscle in the left eye
-Left eye turns right
165
Each olfactory receptor neuron has how many different protein receptors on it?
Only one.
166
In the olfactory bulb, what is the purpose of the glomeruli?
A glomerulus is a focal spherical region where the terminal aborizations of many olfactory nerves contact the dendritic tree of a single mitral cell.
Each glomerulus processes information about a specific class of odorant molecules.
167
Explain how every odorant molecule elicits a unique pattern of responses in a set of related olfactory receptor neurons (ORNs).
Each odor molecule stimulates the proteins of a specific subfamily, some strongly and others weakly.
168
Describe the vomeronasal organ.
- Incisive ducts open into paired, elongated ducts located in the hard palate.
- The ducts are lined by olfactory and respiratory epithelium, surrounded by cartilage.
- Vomeronasal system is specialized for pheromones involved in social and mating behaviors.
169
Name some of the targets of olfactory bulb projections in the pyriform lobe.
- Olfactory cortex
- Olfactory trigone
- Amygdala
- Entorhinal cortex
170
T/F: The amygdala is strongly interconnected with the olfactory system.
TRUE
171
From the olfactory regions of the pyriform lobe, where are the projections?
- Through the dorsomedial thalamus
| - To the orbitofrontal and insular cortex
172
Name some functional considerations of olfaction.
- Feeding behavior (foraging, inspection, ingestion)
- Mating
- Trained sniffing dogs
173
What are the four basic tastes? What causes each?
- Saltiness --> presence of Na ions
- Sourness --> acidity; hydronium ions
- Sweetness --> presence of sugars
- Bitterness --> distaste to avoid poisons
174
As far as taste is concerned, what nerves innervate what?
CN VII --> rostral 2/3 of tongue
CN IX --> caudal 1/3 of tongue
CN X --> epiglottis, palate, larynx, pharynx
175
What three stimuli result in what we refer to as "flavor"?
Taste + Smell + Chemical irritation
176
From the cranial nerves associated with taste, where does the signal go next?
Rostral solitary nucleus in the medulla.
177
What taste function does the gustatory neocortex near the SI face are serve?
Discriminative function
178
What taste function does the anterior insular cortex serve?
Affective function
179
What types of neurons are considered the final common pathway by which the brain and spinal cord influence motor output?
Alpha-motorneurons
180
Define: Motor unit
A single alpha motorneuron and all the muscle fibers it innervates.
181
T/F: Smaller motor units are found in muscles involved in fine motor control.
TRUE
182
What is the result of more motor units being recruited, each firing more rapidly?
An increase in muscle tension
183
Where do both alpha and gamma motor neurons originate?
Trigeminal motor nucleus
184
If alpha-motorneurons innervate striated muscled fibers, what do gamma-motorneurons innervate?
Muscle spindles (aka intrafusal fibers)
185
Where are golgi tendon organs located and what do they do?
Located in muscular tendons
| They detect muscle tension
186
What is the name of the test where a patient's knee is tapped with a mallet? Describe the mechanics of the outcome.
The Myotactic reflex
A rapid stretching of the muscle and muscle spindles activates 1A afferents, producing a monosynaptic muscle contraction.
187
In the example of the hand on hot stove, describe the Flexor reflex.
- Extensors are inhibited when flexors are excited
- Interneuron with filled cell body is inhibitory
- Unfilled cell body is excitatory
188
In the example of stepping on a nail, describe the crossed extension reflex.
- On side of nail, extensors are inhibited and flexors are excited
- On side counter to nail, extensors are excited and flexors are inhibited
- As a result, posture is maintained
189
Describe central pattern generators.
- They operate at the local spinal level
- They generate basic rhythmic motor output
- Their activity is modified by descending input
190
Which descending motor tracts maintain posture?
Ventromedial tracts
191
What muscles are controlled by the ventromedial tracts?
- Muscles of the axial skeleton
- Muscles of limb girdles
- Muscles of the proximal limb
192
The lateral vestibulospinal tract is responsible for what, in reference to the descending motor tracts?
- Stimulates extensors
| - Inhibits flexors
193
The reticulospinal tract is responsible for what, in reference to the descending motor tracts?
- Stimulates flexors
| - Inhibits extensors
194
The tectospinal tract is responsible for what, in reference to the descending motor tracts?
- Muscles of the neck and upper trunk
| - Orienting responses
195
What muscles are controlled by the dorsolateral tracts?
Distal muscles of the limbs
196
T/F: The dorsolateral tracts are involved in involuntary movements.
FALSE
| Involved in voluntary movements
197
The rubropinal tract is responsible for what, in reference to the descending motor tracts?
Affects forelimb muscles
198
The corticospinal tract is responsible for what, in reference to the descending motor tracts?
Affects distal muscles of both sets of limbs
199
The corticopontine tracts, where do they terminate and what do they do?
erminates in the pontine nuclei
| Influence the cerebellum
200
The corticobulbar tracts, where do they travel and what do they do?
Travel from cortex to brainstem
| Influence cranial nerve motor nuclei via the reticular formation.
201
To what two areas does the corticospinal tract terminate?
- Red nucleus
| - Brainstem
202
Name the descending pathways from the brainstem that modify the programs generated by spinal cord CPGs.
- Vestibulospinal (VST)
| - Reticulospinal (RetST)
203
Name the descending pathways from the midbrain that modify the programs generated by spinal cord CPGs.
- Tectospinal (TST)
| - Rubrospinal (RST)
204
Name the descending pathways from the cerebral cortex that modify the programs generated by spinal cord CPGs.
- Corticorubral
- Corticobulbar
- Corticospinal
205
Name some elements required for coordinated movement.
- Intended direction
- Force
- Target
- Feedback on the status of the current movement
206
What is the role of the basal ganglia in the coordination of motor activity?
Continually updates which cortical activity is important, then gates the thalamus accordingly
207
What is the role of the cerebellum in the coordination of motor activity?
Provides for precise timing of movements, with continual direct sensory feedback.
208
What comprises the dorsal striatum in the basal ganglia?
Caudate + Putamen
209
What comprises the ventral striatum in the basal ganglia?
Nucleus accumbens + Olfactory tubercle
210
In the basal ganglia, each striatal neurons receives ~ 10,000 synapses. Are they mostly excitatory or inhibitory, and where are they coming from?
Excitatory
| Cerebral cortex and Thalamus
211
What is another name for the lateral hemisphere of the cerebellum?
Cerebrocerebellum
212
What two sections comprise the spinocerbellum?
Vermis (central portion, saggitally)
+
Medial hemisphere (aka intermediate zone)
213
What two structures comprise the vestibulocerebellum?
Nodulus + Flocculi
214
Describe the roles of all three cerebellar peduncles.
Rostral Cerebellar Peduncle --> output to red nucleus
Middle Cerebellar Peduncle --> input from the pons
Caudal Cerebellar Peduncle --> input from vestibular nuclei, spinal cord; output to reticular formation and vestibular nn.
215
T/F: All Purkinje cells project to deep cerebellar nuclei, which generate the outputs of the cerebellum to other brain regions.
FALSE
An exception is that Purkinje cells of the vestibulocerebellum synapse
directly on neurons in the vestibular nuclei. So in this resepct the
vestibular nuclei act as an additional deep cerebellar nucleus.
216
For the vestibulocerebellum, what are the inputs? The outputs? The functions?
Inputs --> vestibular nerve and nuclei
Outputs --> vestibular nuclei
Function --> equillibrium; coordination of head and eye movements
217
For the spinocerebellum, what are the inputs? The outputs? The functions?
Inputs --> spinal cord; trigeminal nerve; vestibular nerve
Outputs --> fastigial --> globose --> emboliform nuclei --> brainstem motor centers
Function --> vermis = posture and locomotion; medial hemispheres = motor coordination of extremities
218
For the cerebrocerebellum, what are the inputs? The outputs? The functions?
Inputs --> pontine nuclei
Outputs --> dentate nucleus --> red nucleus --> motor thalamus --> motor and premotor cortex
Function --> planning movements and fine motor control
219
For the following cerebellar dysfunction, give a brief description:
- Ataxia
- Dysmetria
- Hypermetria
- Wide-gait standing/walking
Ataxia --> incoordination in locomotion
Dysmetria --> inaccuracy of movement
Hypermetria --> overshooting of target
Wide-gait standing/walking --> width of stance
220
Contrast the discriminative and affective components of sensation and experience.
Discriminative --> what is it? what color is it? What size is it?
Affective --> how does it feel to me?
221
Name some locations the axons of dopaminergic neurons in the ventral tegmental area project to.
- Amygdala
- Septum
- Ventral striatum
- Ventral pallidum
- Limbic cortex
222
What major brain divisions are involved in the emotional brain?
- Diencephalon
- Brainstem
- Spinal cord
223
Name some of the components of the diencephalon that play a role in the emotional brain.
- Hypothalamus
- Anterior thalamic nucleus
- Mediodorsal thalamic nucleus
- Mamillary body
224
Name some of the components of the brainstem that play a role in the emotional brain.
- Periaquductal gray
- Monoaminergic cell bodies
- Parabrachial nucleus
- Solitary nucleus
- Dorsal motor nucleus of CN X
225
Name some of the components of the spinal cord that play a role in the emotional brain.
- Intermediolateral cell column
| - Sacral cord parasympathetics
226
T/F: The hypothalamus and amygdala are strongly interconnected via the stria terminalis.
TRUE
227
T/F: Neurons in several portions of the emotional brain contain neurons with receptors for steroid hormones.
TRUE
228
What are the two main subcortical axon tracts linking the prosencephalic and brainstem portions of the emotional brain? Describe the axons of these tracts.
- Medial forebrain bundle
- Dorsal longitudinal fasciculus
Axons are thinly myelinated.
229
Name the major regions of motor output from the emotional brain.
- Amygdala
- Hypothalamus
- Septum
- Cingulate
- Orbitofrontal cortex
- Insular cortex
230
Name some common neurotransmitters used by monoaminergic neurons in the emotional brain.
- Dopamine
- Serotonin
- Noradrenaline
231
The emotional brain functions in coordination with which three major body systems?
- Somatomotor
- Visceromotor
- Endocrine
232
Name some emotional behaviors that are goals of the emotional brain.
- Eating food
- Drinking
- Fighting
- Escaoe
- Courtship
- Mating
- Social
233
What system is often referred to as the "reward pathway"?
The mesolimbic dopaminergic system
234
Name the main target of dopaminergic input in the "reward pathway". This goal is apart of the...?
Nucleus accumbens
| main component of the ventral striatum
235
Compare and contrast the functions and aspects of the two parallel striato-pallidal pathways.
```
VENTRAL
Behavioral role --> emotional
Pallidal target --> ventral pallidum
Thalamic target --> mediodorsal nucleus
Source of input --> ventral tegmental area
```
```
DORSAL
Behavioral role --> cognitive
Pallidal target --> dorsal pallidum
Thalamic target --> ventrolateral nucleus
Source of input --> substantia nigra
```
236
What role in the emotional brain does the periaqueductal gray of the midbrain play?
Coordinates behavioral and autonomic responses to threatening situations.
- Fight/Flight response
- Freezing response
- Vocal expression
237
What types of reactions does the amygdala manage?
Survival reactions, particularly those associated with fear.
238
Name some systems acting upon the amygdala.
- Visual system
- Auditory system
- Somatic sensory system
- Olfactory system
- Stress hormones from the adrenal gland
239
Describe the orbitofrontal cortex (OFC).
- Receives input from olfactory, taste, vision, and somatosensation.
- Involved in learning which stimuli are rewarding and which are not.
240
Name some of the information integrated by the insular cortex.
- Body homeostasis
- Pain
- Temperature
- Visceral afferents
- Sensations of stress
**Collectively known as interoception
241
How are afferents from the insular cortex conveyed to the thalamus?
Via small caliber axons that travel with the spinothalamic tract (STT).
242
Contrast the insula and the cingulate cortex.
Insula --> feeling
| Cingulate cortex --> motivations
243
The temporal pole cortex is important in representing what?
Abstract, conceptual knowledge.
244
What are some valuable questions to ask an owner when getting a neurological history?
- Vaccination status
- Travel history
- Toxin exposure
- History of trauma
- Previous therapy
- Other illness
245
Name some signs of a pons deformity.
- Depression
- Trigeminal atrophy of the head
- Reflexes normal or hyper
- Ipsilateral hemiparesis
246
Name some signs of idiopathic facial nerve paralysis.
- Inability to move eyelid, lip, and ear
- Loss of palpebral reflex
- Decreased tear production
247
What is vestibular syndrome?
- Loss of balance
- Difficulty walking
- Abnormal posture
- Abnormal eye movement
248
Name some factors that influence neuroplasticity.
- Hormones
- E-Stimulation
- Disease
- Experience
- Injury
- Drugs
249
T/F: Brain reorganization is learning independent.
FALSE
| Dependent
250
Name the four measurements of neuroplasticity following a stroke.
- Behavioral
- Motor mapping
- Histological
- Functional MRI
