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Neuro > Patho > Flashcards

Patho Flashcards

1
Q

What are concentrated in the Nodes of Ranvier?

A

Voltage-gated Na Channels

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2
Q

What layer of the peripheral nerve aids regeneration of neurons?

A

Endoneurium

Does not extend into the CNS which is why limited regeneration occurs in CNS

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3
Q

What are fascicles? What surrounds them?

A

bundles of nerves composed of endoneurium & blood vessels

surrounded by perineurium

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4
Q

What do oligodendrocytes form? Where are they located?

A

Form myelin in the CNS

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5
Q

How are oligodendrocytes of CNS different than the schwann cells of PNS?

A

Oligodendrocytes cover multiple axons at once; schwann cells cover a single axon

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6
Q

What do astrocytes to in CNS (5 functions)? What types of matter are they composed of?

A

Function:

  1. waste & metabolite transport
  2. uptake of neurotransmitter (regulate synaptic activity)
  3. ion concentration regulation
  4. maintains tight junctions between capillaries that forms BBB
  5. role in repair and scarring in brain

Astrocytes are composed of grey matter

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7
Q

What is gliosis?

A

When astrocytes fill cytoplasm with microfibrils forming special scar tissue in CNS when tissue is destroyed

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8
Q

Job of microglia?

A

phagocytic cell that cleans up debris after cell damage, infection, or cell death

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9
Q

Function of ependymal cells?

A

Forms lining of neural tube cavity (the ventricle system)

In some areas, ependymal cells combine with a rich vascular network to form the choroid plexus where CSF production occurs

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10
Q

Briefly describe an AP.

A
  • cell at rest (-90mV)
  • stimulus occurs
  • nerve depolarized to threshold potential (-60mV)
  • Na channels open and Na floods into the cell further depolarizing cell (+30mV)
  • inactivation gate on Na voltage gated channels close
  • K channels open & K floods out of cell repolarizing cell
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11
Q

Phases of an action potential?

A
  • depolarization
  • overshoot
  • repolarization
  • resting/polarized
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12
Q

Excitatory neurotransmitters (6)

A
  • ACh
  • Serotonin
  • Dopamine
  • NE
  • Epi
  • Glutamate
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13
Q

Inhibitory neurotransmitters (2)

A

glycine

GABA

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14
Q

Neuropeptides (pain sensation and perception)

A

Neuromodulators & neurohormones - modify work of other NT

substance P
endophins
enkephalins

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15
Q

_____ neurons of the CNS have short preganglionic neurons that release __2__ and act on __3__ receptors of ___4____ postganglionic neurons that release __5___ or ___5___.

A
  1. Sympathetic
  2. ACh
  3. N2 receptors
  4. long
  5. ACh or NE
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16
Q

__1__ neurons of the CNS have long preganglionic neurons that release __2__ to act on __3__ receptors of ___4___ postganglionic neurons, that release __5____.

A
  1. Parasympathetic
  2. ACh
  3. N2
  4. short
  5. ACh
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17
Q

__1__ neurons have single __2___ that release __3__ to act on __4__ receptors of ___5__.

A
  1. Somatic
  2. motoneuron
  3. ACh
  4. N2
  5. Skeletal muscle
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18
Q

When stimulated by a motoneuron, the nicotinic 2 receptor, activated by ACh, opens what ion channels?

A

Na & K

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19
Q

Sequence of events in neuromuscular transmission (7)

A
  1. AP travels down motoneuron to presynaptic terminal
  2. depolarization opens Ca channels, and Ca flows INTO the presynaptic terminal
  3. Exocytosis of ACh
  4. ACh binds N2 on motor end plate
  5. Na and K channels open
  6. depolarization of motor end plate causes AP in muscle
  7. ACh degraded to choline and acetate by acetylcholinesterase and reuptake occurs by Na-choline cotransporter
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20
Q

Most common type of intracranial neuroepithelial type tumor?

A

Astrocytoma (80%) - neuroglial tumor

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21
Q

What is medulloblastoma?

A

cancer of blastocytes in cerebellum (undifferentiated cells) in infants and children

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22
Q

What percentages of the bodies O2 does the brain use? What percentage of the cardiac output does it receive?

A

O2: 20%
CO: 15%

without O2 cells stop functioning in 10s and die in 4-6 min

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23
Q

What is the major fuel source of the brain?

A

glucose

no glycogen stores (like muscle cells) so relies on blood supply and glial cell stores

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24
Q

describe the hierarchy of control

A

the forebrain controls the brainstem

and

the brainstem controls the spinal cord

dominance of forebrain because it is made later in development, more specialized, and built from earlier structures

newer functions added onto older functions anteriorly, making them more vulnerable to injury

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25
Q

what does the ectoderm create during neural development?

A
  • neural plate (primordial nervous system)

- neural tube

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26
Q

What does the neural crest become as it moves rostrally?

A
  • neurons
  • support cells of PNS
  • 10 most rostral segments (fore brain, mid brain, hind brain)
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27
Q

what is the neural plate the primordial of?

A

nervous system

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28
Q

what does the neural tube become?

A

CNS

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29
Q

what is the soma?

A

skin, muscle, and skeletal structures of body wall innervated by somatic nervous system

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30
Q

what innervates the viscera?

A

autonomic nervous system

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31
Q

List the 5 cell column types.

A 
Dorsal Root Ganglia
Dorsal Horn cell column
ventral horn cell column
sympathetic chain ganglia
parasymphathetic chain ganglia
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32
Q

Name the 4 cell columns contained within the dorsal root ganglia.

A

special somatic afferent
general somatic afferent
special visceral afferent
general visceral afferent

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33
Q

What information do the special somatic afferents convey & where are they located? Where are their receptors located?

A

internal sensory information
i.e. joint & tendon sensation, proprioception, position, posture and movement of body

SSA are located in dorsal root ganglia

receptors primarily located in muscles, tendons, and joints

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34
Q

What information do special sensory IA cell column relay? Where to they originate?

A

the IA cell columns relay information (from the special sensory afferents in the dorsal ganglion) to reflexes concerned with posture and movement

they also send information to:

  • the cerebellum (for coordination of movement)
  • the forebrain (contributes to the experience of the information)

they are originate in the dorsal horn column

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35
Q

what do general somatic afferents innervate? what is their distribution? what information do they convey? where are they located?

A

they innervate the skin & other somatic structures with a wide distribution

information about pressure & pain, touch, and temperature

located in the dorsal root

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36
Q

What information do general somatic afferent IA neurons convey? where do they originate?

A

general somatic afferent IA neurons relay info to:

  • protective & local reflexes
  • forebrain (so information can be precieved as sensation - pressure, pain, hot, cold)

they originate in the dorsal horn

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37
Q

What do special visceral afferents innervate? what information do they convey? where are they located?

A

they innervate specialized gut related receptors such as taste buds and olfactory mucosa

special visceral afferents convey information about the gut

they are located in the dorsal root ganglion

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38
Q

what information do special visceral IA columns convey? where do they originate?

A

information from gut to:

  • reflex circuits to produce salvation, chewing, and swallowing
  • forebrain for perception (taste and smell)

they originate in the dorsal horn

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39
Q

What do general visceral afferents innervate? what information do they convey?

A

GVA innervate visceral structures of the GI & GU systems, heart, and great vessels

convey information about fullness and discomfort

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40
Q

What do GVA-IA neurons innervate?

A

GVA-IA relay info to:

  • vital reflex circuits
  • forebrain: for experience of bladder pressure and stomach fullness
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41
Q

What do OA do? what system do them work in?

A

relay information to LMN

they work in the ventral horn

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42
Q

what are GVE (preganglionic neurons)? where do they work? are they sensory or motor?

A

they are output neurons of the ANS (SNS and PSNS)

they work in the ventral horn cell column

they are motor neurons

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43
Q

what do SVE (or pharyngeal efferents) innervate? are they motor or sensory?

A

they innervate the muscles of mastification, facial expression, pharynx, and larynx. As well as the mm for moving the head.

they are motor neurons

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44
Q

what do the GSE supply?

A

they supply motor output to skeletal muscle

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45
Q

what is the final common pathway refer to?

A

LMN

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46
Q

Trace the course of a UMN.

A

motor cortex
crosses in medulla in pyramid
ends in grey matter of ventral horn cell column at level it will work upon

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47
Q

how many cell columns are in the dorsal horn cell column? in the ventral cell column?

A

4 in dorsal

3 in ventral

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48
Q

what type of matter makes up longitudinal tracts? what are the three layers that make them up?

A 
white matter
layers:
inner - archilayer
middle - paleolayer
outer - neolayer
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49
Q

describe the significance of the archilayer of the longitudinal tracts.

A
  • embryonic neurons migrate to this layer to form the reticular formation
  • contains circuits for reflexes
  • as it enters brainstem it gets bigger and contains VITAL reflexes (respiration, cardiovascular fxn, swallowing, vomiting)
  • reticular activating system is in the lateral portion of the reticular formation of the medulla, pons, midbrain
  • sensory from all modalities enter here including somatosensory, auditory, visual, and visceral afferents
  • made of short fibers
  • maximum of 5 segments
  • allows motor neurons to act together
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50
Q

what is the significance of the paleolayer of longitudinal tract?

A

contains most of the major fiber tracts required for sensation and motor function

larger diameter, longer fibers of the spinoreticular and spinothalamic tracts

functional at birth

*Facilitates primitive functions

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51
Q

what is the significance of the neolayer of longitudinal tracts?

A

necessary for delicate, highly coordinated skills like manipulative finger and toe movements

functional at 2 years of age

babies lack a developed paleolayer which is why they can’t do anything)

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52
Q

what layers of the longitudinal tracts have collateral communication pathways between grey matter? what is the significance of this?

A

the inner and middle layers

provides alternative route to bypass damage

the outer layer lacks this so if it is damage there is loss of function

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53
Q

A patient with a stroke has lost the ability to make fine motor hand movements. What layer of the longitudinal tract was most likely damaged? Which is intact?

A

the neolayer was damaged so they lost distal hand function

but the paleolayer is intact which preserves basic life functions

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54
Q

Name the two pyramidal tracts. Are these ascending or descending tracts? Where do they cross? Which is the bigger tract?

A
  • lateral corticospinal tract (bigger): crosses in pyramid
  • anterior corticospinal tract: crosses at spinal cord level

they are descending tracts

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55
Q

what information do spinothalamic tracts convey? where do they terminate?

A

conscious pain, temperature, CRUDE touch, and pressure

there is a lateral and anterior tract

they terminate in area of cerebral cortex which perceives these sensations

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56
Q

what does the cerebral cortex do, where is it?

A

outer layer of cerebrum
made of folded grey matter
important for consciousness

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57
Q

where do extrapyramidal tracts control impulses? are they voluntary?

A

at segmental level

they are not voluntary

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58
Q

where does the spinal cord span to and from?

A

foramen magnum at base of skull to L1 or L2

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59
Q

what is the cauda equina?

A

when the dorsal and ventral roots of the caudal portion of spinal cord angle downward

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60
Q

what replaces cell columns in the brain stem?

A

nuclei

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61
Q

Functions of medulla?

A

autonomic center for breathing, BP, and reflexes of swallowing, coughing, and vomiting

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62
Q

function of pons?

A

attached to cerebellum

aids in balance and breathing

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63
Q

function of midbrain

A

eye movement

contains relay nuclei of auditory and visual systems

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64
Q

what is the major relay center for information going to and from the cerebral cortex?

A

the thalamus (somatic)

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65
Q

what are the dorsal horn and ventral horn parts of the diencephalon?

A

dorsal horn - thalamus & subthalamus

ventral horn - hypothalamus

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66
Q

Where information is processed by the thalamus?

A

Sensory information going TO the cerebral cortex

Motor information coming FROM the cerebral cortex going TO the brainstem & spinal cord

Information of the RAS

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67
Q

What system does the sub thalamus contain?

A

movement control systems related to the basal ganglia

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68
Q

what is the function of the hypothalamus?

A

Autonomic
integration of homeostatic control of bodies internal environment (blood gas, water balance, good consumption, endocrine, ANS)

69
Q

what is the internal capsule?

A

broad band on fibers between thalamus and basal ganglia

contains fibers that connects cerebral cortex to deeper structures (basal ganglia, thalamus, midbrain, pons, medulla, spinal cord)

70
Q

Describe the corpus collosum, gyrus, and sulci of the teleencephalon.

A

corpus collosum: axons connecting cortexes of two lobes (cerebral hemispheres)

gyrus: ridges
sulcus: valley between two ridges

71
Q

what happens when broca’s area and wernicke’s area damaged?

A

damaged broker’s area = speech production impairment

damaged wrenicke’s area = speech/written language comprehension impairment

72
Q

what two body parts make up the majority of the motor and sensory cortexes?

A

hands

head (mouth)

73
Q

What is the progression from superior to inferior of the body related to the sensory and motor cortexes?

A

superior

  • feet
  • trunk
  • hand
  • neck
  • eyes
  • face
  • lip
  • jaw
  • tounge
74
Q

Number of cervical, thoracic, lumbar, sacral, and coccygeal spinal nerves??

A 
cervical - 8
thoracic - 12
lumbar - 5
sacral - 5
coccygeal - 2+
75
Q

Cervical nerves 1-7 pass __1__ their corresponding vertebra. Cervical nerve 8 passes above __2___ vertebra. Thoracic nerves 1-12 pass __3___ their corresponding vertebra.

A
  1. above their vertebra
  2. above T1
  3. below their vertebra
76
Q

After the ventral and dorsal root of nerves merge they divide into: __ and ___

A

dorsal primary rami

ventral primary rami

77
Q

dorsal primary rami contain what type of fibers?

A

sensory fibers and motor fibers to the back

78
Q

ventral primary rami contain what type of fibers?

A

motor and sensory fibers to the anterior trunk and extremeties

79
Q

what are the meninges? what three layers compose them?

A

protective membranes surrounding the brain and spinal cord

  1. pia mater
  2. arachnoid mater
  3. dura mater
80
Q

describe the pia mater

A

adheres to brain, contains blood supply, and allows no liquid penetration

81
Q

describe arachnoid mater

A

web-like trabeculations filled with CSF, helps with shock absorption, allows no liquid penetration

82
Q

describe dura mater

A

2 membranes (acts as one)
one attached to bone
tough
forms dural venous sinuses for veins to pass through (superior and inferior sagittal sinus, cavernous sinus, transverse sinus)

83
Q

what does the subarachnoid space lie between? what does it contain? is it real or potential?

A

pia mater and arachnoid space
contains CSF & weblike trabeculations
real space

84
Q

Is the sub-dural space real or potential? When a bleed occurs it is usually ____ pressure from the ____ system.

A

potential

When a bleed occurs it is usually low pressure from the venous system.

85
Q

What does the epi-dural space lie between? Is the epi-dural space real or potential? When a bleed occurs it is usually ____ pressure from the ____ system.

A

lies between bone and dura mater

potential space

When a bleed occurs it is usually high pressure from the arterial system.

86
Q

What freely passes through the brain barriers? What also can pass through the barrier? Of these which has the highest rate of diffusion across the barrier?

A

water, CO2, & O2

medications: lipid soluble drugs diffusing faster

87
Q

CSF brain barrier is composed of ____ _____ epithelial cells. These cells facilitate ___.

A

choroid plexus

These cells facilitate waste removal

88
Q

Does the Brain have lymphatic vessels?

A

No, it but it does have immune cells

89
Q

List the arteries that make up the circle of willis

A
  • 2 vertebral arteries
  • 1 basal artery (splits to 2 posterior cerebral arteries)
  • 2 internal carotid
  • 2 middle cerebral arteries
  • 2 anterior cerebral arteries
90
Q

where does the venous drainage of the brain occur?

A

into the dural venous sinuses and into the internal jugular vein within the dura mater

91
Q

What are the significances of the cavernous and transverse sinuses?

A

cavernous - close to nose can important infection from zit

transverse - close to ear can import infection from ear infection

92
Q

What is the ventricular system, how many, names of them?

A 
cavities filled with CSF
there are 4 ventricles:
- 2 lateral
- 3rd ventricle
- 4th ventricle
93
Q

what is the choroid plexus? where do they arise?

A

specialized capillaries that produce CSF (125-150mL)

they arise in pia mater, in the lateral, 3rd, and forth ventricles

94
Q

where is CSF reabsorbed?

A

through arachnoid villi located in the subarachnoid space in the sagittal sinus

95
Q

ventricular drainage of CSF?

A

arachnoid villi to right and left ventricle to 3rd ventricle to 4th ventricle to subarachnoid space to cistern in spinal cord or superior sagittal sinus

96
Q

Where are nociceptors and thermoreceptors located?

A

skin
thermoreceptors - temp
nociceptors - extremes of pain & temperature

97
Q

Mechanoreceptors sense what 3 things? what types of receptors do they have and where are they located?

A

touch
audition
vestibular

98
Q

photo receptors modality:

A

vision

99
Q

chemoreceptors sense 4 things, list them, their receptors, and the location of their receptors.

A
  1. olfaction
  2. taste
  3. PaO2
  4. pH of CSF
100
Q

Describe the sensation encoded by the following mechanoreceptors:

  1. pacinian corpuscle
  2. meissner’s corpuscle
  3. Hair follicles
  4. ruffini corpuscle
  5. merkel’s receptors
A
  1. pacinian corpuscle: vibrations
  2. meissner’s corpuscle: 2 point discrimination
  3. Hair follicles: velocity and direction of movement
  4. ruffini corpuscle*: stretch and joint rotation
  5. merkel’s receptors: vertical indentation of skin
101
Q

where does input for proprioceptive information come from?

A

muscles, tendons, joints, & stretch fibers in skin

102
Q

what type of fibers make up thermal, mechanical, and polymodal NOCICEPTOR receptors?

A

sensory and motor

thermal and mechanical - myelinated A delta fibers (they are fast; example: fast pain, touch, pressure, temp)

polymodal - unmyelinated C fibers (ex. slow pain, postganglionic autonomic nerves, olfaction)

as you go down alphabet and roman numerals nerve fibers get slower and smaller
1-a= motorneuron = largest and fastest

103
Q

what makes up a sensory unit?

A

receptor, ganglion, and axon

104
Q

describe the 1st, 2nd, 3rd neuron sensory system arrangement?
at what levels are many interneurons located?

A

first order neurons: periphery to CNS (dorsal horn)

second order neurons: reflex networks and to the thalamus (up a tract)

third order neurons: thalamus to cortex

many interneurons process and modify information at level of the 2nd & 3rd order neurons

105
Q

Where do spinothalamic nerves cross the spinal cord?

A

when they enter the spine (crosses dorsal horn grey matter)

106
Q

what sensory units are required for the limb and trunk? what sensory units are required for the face and cranial structures?

A

Dorsal Root Ganglion is required for the limbs and trunk.

Trigeminal sensory neurons are required for the face and cranial structures

107
Q

where do the cranial nerves send their axons to?

A

nuclei in the brainstem

108
Q

another term for dorsal column

A

medial lemniscal pathway

109
Q

what information does the dorsal column transmit?

A

RAPID transmission of:
discriminative touch
proprioception
vibration

110
Q

describe the pathway of the dorsal column (3 neurons)

A
  1. receptor through dorsal root ganglion to dorsal horn of spinal cord
  2. transmitted to dorsal column
    information travels up dorsal column of white matter to the input association neurons in the medulla (called the medial lemniscus)
    In the medulla the axons cross at the medial lemniscus and travel to the thalamus
  3. The fibers than go to the primary sensory cortex
111
Q

What pathway are you stimulating when you use a tuning fork to assess sensation of a boney joint?

A

Dorsal column - medial lemniscus pathway or discriminative pathway

112
Q

What pathways is required for stereognosis (identifying objects without looking at them)?

A

afferents to dorsal horn to dorsal column - medial lemniscus pathway

proprioception information travels up the dorsal column (white matter) to the medulla (where it crosses), passes to the thalamus (integrates sensory and motor information), and final message sent to the primary somatosensory cortex

113
Q

What two things must a patient have for stereognosis to occur?

A

higher order parietal association cortex must function

prior learning of object

114
Q

what is astereognosis?

A

When the patient cannot associate the shape of the object with the name of the object

Occurs when dorsal column pathway is intact but when the parietal association cortex is broken

115
Q

What is another name for the lateral spinothalamic and anterior spinothalamic pathways?

A

neospinothalamic - lateral

paleospinothalamic - anterior

116
Q

what information does the lateral spinothalamic tract convey? rapid or slow?

A

bright, sharp pain through 3 AXON pathway

relatively rapid transmission

117
Q

what information does the anterior spinothalamic pathway convey? rapid or slow?

A

transmission of information that is general (doesn’t require discrete localization or intensity) SLOW transmission

slow pain, temp, crude touch, pressure

it is older

118
Q

what does the RAS/reticular formation control

A

startle reflex, wakefulness, BP, and HR (ANS)

119
Q

where does the anterior spinothalamic pathway convey fibers to?

A

RAS in brainstem

intralaminar nuclei of thalamus which connects to LIMBIC system providing touch with the affective/emotional aspects

120
Q

describe the functions of 1st, 2nd, and 3rd order neurons in the somatosensory system

A

1st: transmit info from periphery to CNS (through dorsal root ganglion neuron or trigeminal sensory neurons)
2nd: transmit infö from CNS to thalamus (and/or initiate reflexes at spinal cord level)
3rd: transmit info from thalamus to cerebral cortex

121
Q

what is the pathway of the anterolateral pathway

A

receptor to dorsal root ganglion to dorsal horn

crosses at anterior commissure at segment level to the anterolateral tracts

lateral goes to thalamus and than to cortex

anterior gives fibers to RAS than goes to thalamus (gives fibers to limbic system for emotion), and than to cortex

122
Q

what 4 things does perception involve?

A

awareness of stimuli
localization
discrimination of characteristics
interpretation of their meaning

123
Q

where does interpretation occur?

A

thalamus - here it enters the consciousness and is interpreted into rough localization and crude sense

somatosensory cortex - full interpretation

124
Q

where is the primary somatosensory cortex located?

A

parietal lobe

125
Q

where is the somatosensory association cortex and what is it function?

A

behind primary somatosensory cortex and transforms raw material into experience by integrating information with past experiences

126
Q

where is the ANS located? what is its function?

A

CNS and PNS

coordinated and maintains a steady stage amount viscera

127
Q

In the ANS, which is myelinated and which is unmylinated: preganglionic neuron and post ganglionic neurons

A

preganglionic - myelinated

post ganglionic - unmyelinated

128
Q

where does the SNS receive input from?

A

T1-L2

thoracolumbar division

129
Q

The sympathetic chain ganglia is ____vertebral; while the sympathetic ganglia is ___vertebral.

A

The sympathetic chain ganglia is paravertebral; while the sympathetic ganglia is prevertebral.

130
Q

where does the PNS receive information from?

A

cranial nerve nuclei and sacral region of spinal cord

craniosacral division

131
Q

where do preganglionic neurons travel to in the PNS?

A

ganglia close to the organs they innervated

132
Q

the descending motor tract involves what parts of the brain?

A

brain stem, cerebellum, basal ganglia, and motor cortex

133
Q

where is the motor cortex located?

A

posterior aspect of frontal lobe

134
Q

name the 3 parts of the motor cortex

A

primary motor (aka motor strip)
premotor
supplementary motor cortex

135
Q

where does the motor cortex collect information from

A 
thalamus
sensory cortex
cerebellum
basal ganglia 
premotor cortex
136
Q

the motor cortex is divided by the “motor homunculus” what parts receive the most innervation? what is the role of the motor cortex?

A

hands, face (for speech)

the motor cortex controls specific muscle movements

137
Q

What type of movements are generated by the premotor cortex?

A

patterned movements (done by prefrontal association cortex)

this lies anterior to the motor cortex

138
Q

what type of movements does the supplementary motor cortex control?

A

complex, skillful movements that involves both sides of the body

139
Q

Name a few places the output neurons of the primary motor cortex project to.

A
  • Premotor and somatosensory areas on the same side
  • Opposite side of the cortex
  • Descend to subcortical structures such as the basal ganglia and thalamus
  • Brain stem and spinal cord
140
Q

Describe the tract of the UMN (the pyramidal system).

A

bet cells in the primary motor cortex to internal capsule through pons and medulla to pyramids to segmental level of spinal cord LMN

(may also travel down corticobulbar tract instead of corticospinal)

141
Q

where to 80% of UMN cross? what is the name of this tract?

A

at the junction between the medulla and spinal cord (at the pyramidal system)

this is called the lateral corticospinal tract

142
Q

what corticospinal tract does not cross in the medulla? what vertebral level does it most commonly innervated?

A

anterior corticospinal tract

the cervical level

143
Q

where do cells in the extrapyramidal system originate? how do they differ from the pyramidal system?

A

premotor cortex
supplementary cortex
basal ganglia

they don’t follow the same route (don’t go thru pyramids)

their axons are project to the reticular formation (in the brainstem) and the reticulospinal system (to ancient LMN)

144
Q

how are pyramidal disorders characterized?

A

spasticity and paralysis

145
Q

how are extrapyramidal disorders characterized?

A

involuntary movements, ridigity, immobility without paralysis

146
Q
  1. what is the reflex called that involves structures in the brain?
  2. what is the reflex called that involves multiple segments?
  3. what is the reflex called that involves one cord segment?
A
  1. suprasegmental
  2. intersegmental
  3. segmental
147
Q

what reflex is important for muscle tone and posture? when should you test it?

A

stretch reflex

test when person has problems with mm tone or posture

148
Q

what are the two type of stretch receptors? what information do they transmit? for what purpose?

A

muscle spindle receptors - they transmit information about muscle LENGTH and RATE of stretch (contracts mm, maintains muscle tone)

golgi tendon receptors - transmits info about muscle TENSION or FORCE of contraction (relaxes mm before you rip it)

149
Q

what type of neurons does the muscles spindle work with?

A

Ia nerve fibers (they are intrafusal fibers - specialized sensory organs for detecting length and rate of stretch)

150
Q

describe the pathway of the stretch reflex

A

muscle spindle detects stretch (mechanoreceptor): sends info on Ia neuron to spinal cord, synapses with motor neuron, tells mm to contract

also sends info on mm length to brain (synapses with internuncial neurons), sends this info via dorsal column (to brain stem, cerebellum, and cortex), to send inhibitory stimulus to motor units of antagonistic mm group

151
Q

what is reciprocal innervation?

A

sensory input tells one neuron to contract one muscle and another neuron to relax a different neuron (antagonistic muscle)

152
Q

what type of receptors are muscle spindles 1a neurons?

A

mechanoreceptors with special somatic afferents

153
Q

where are muscle spindles located?

A

in muscle belly

154
Q

What do descending fiber of the motor pathway SYNAPSE with and ACTIVATE? (2 things)… Why?

A

alpha motor neurons
gamma motor neurons

so that the sensitivity of the muscle spindles is coordinated with the muscle movement

155
Q

can we control our stretch reflex?

A

yes, central control over motor neurons allows us to suppress it, otherwise any movement we made would be opposed and prevented by tone maintenance

156
Q

golgi tendon reflex

A

stretch receptors in the tendons
Sense when a muscle contracts (not stretches)
Group Ib afferent neurons are excited
Synapse on inhibitory interneurons in spinal cord
Inhibitory neurons synapse on alpha motor neurons
they inhibit firing of the motor neuron which relaxes the same muscle that was just contracted
Also cause synergistic muscles to relax and antagonistic muscles to contract
Exact opposite of stretch reflex

157
Q

flexor withdrawal reflex

A

Flexor reflex afferent fibers are activated
Synapse on multiple interneurons
Ipsilateral side reflexes are activated that cause flexor response
Contralateral side gets crossed-extension reflex which extends to maintain balance
Afterdischarge makes the flexion stay a while

158
Q

function of basal ganglia

A

Function is to influence the motor cortex via pathways through the thalamus

plan/execute SMOOTH movements
also affective/cognitive function

159
Q

There are two pathways from basal ganglia to motor cortex. which is inhibitory and which is excitatory?

A

inhibitory - indirect

excitatory - direct

160
Q

Parkinsons is caused by damage to which of the two BG/motor cortex pathways? Sx?

A

Both inhibitory and excitatory

Tremors, shuffling gait, slow movements

161
Q

Huntington’s is caused by damage to which of the two BG/motor cortex pathways? Sx?

A

inhibitory

chorea

162
Q

function of cerebellum? what happens with damage?

A

Regulates movement and posture
Helps to control rate, range, force and direction of movement

damage = lack of coordination (loss of inhibitory feedback) = ataxia (errors in rate, range, force, and direction of movement)

163
Q

three divisions of cerebellum?

A

vestibulocerebellar - balance and eye movements
spinocerebellar - syngerny of movements
pontocerebellar - plan and initiate movments

164
Q

examples of cerebellar damage

A

ataxia
uncoordinated movements
dysdiadochokinesia
intention tremors

165
Q

vestibular system function

A

equalibrium and balance
detects angular and linear acceleration of head
creates stable vision image
adjusts posture to maintain balance

166
Q

semicircular canals angular or linear?

A

angular

167
Q

utricle and saccule angular or linear

A

linear

168
Q

how do semicircular canals work? same for otoliths

A

When the head is rotated the endolymph in the canals is “sloshed”, this moves the cupula over the hair cells, which depolarizes the hair cells. The hair cells will either excite or inhibit the afferent vestibular nerves.
Rotation of the head to the left stimulates the left semicircular canals and rotation to the right stimulates the right semicircular canals.

169
Q

where do afferents from the vestibular hair cells terminate

A

Superior, Medial, Lateral, Inferior nuclei in medulla

semicircular canals help with VOR (eye movements)

utricles help with posture

Neuro (4 decks)

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