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somatic functions Flashcards

1
Q

Somatic Motor Pathway

A

Neural pathway for voluntary muscle movements.

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2
Q

Regions Involved:

A

Cerebrum, Motor Cortex, Brainstem, Spinal Cord.

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3
Q

provide a description of the regions involved

Regions Involved: Cerebrum, Motor Cortex, Brainstem, Spinal Cord.

A

Description: Coordinates voluntary movements like writing or playing an instrument.

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4
Q

Consequences of Damage

A

Muscle weakness, Difficulty with voluntary movements, Neurological disorders.

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5
Q

also known as:

A

Voluntary Pathway

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6
Q

not all sensations are ____

A

perceived

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7
Q

Define Sensation:

A

Detection of changes in internal or external environment via sensory receptors.

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8
Q

components of sensation:

A

Involves sensory receptors and neurons transmitting signals to CNS.

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9
Q

define perception:

A

Conscious awareness and interpretation of sensations.

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10
Q

where does processing occur?

A

in the cerebral cortex.

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11
Q

describe Subconscious Processing:

A

Some sensory information processed subconsciously in lower centers like spinal cord and brainstem.

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12
Q

example of subconscious processing:

A

Not consciously aware of blood acidity or CO2 levels, but brain centers receive and respond to this information.

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13
Q

difference between perception and sensation:

A

Perception: Conscious awareness and interpretation.

Sensation: Detection of changes.

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14
Q

Somatic Sensation:

A

Definition: Tactile sensations from skin (touch, pressure, vibration, temperature, pain) and proprioceptive sensations from muscles and joints.

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15
Q

proprioception

A

perception or awareness of the position and movement of the body:
“exercises to improve balance and proprioception”

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16
Q

Special Senses:

A

Definition: Vision, hearing, taste, smell, balance; arise from specific sense organs.

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17
Q

Visceral Sensation:

A

Definition: Sensations from visceral organs like pressure, stretch, chemical concentrations.

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18
Q

Peripheral Nervous System Sensory Types:

A

Somatic Sensations: Skin, muscles, joints.

Special Sensations: Sense organs.

Visceral Sensations: Visceral organs.

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19
Q

Types of Sensory Receptors:

A

Free Nerve Endings: Receptors composed of bare dendrites.

Encapsulated Nerve Endings: Bare dendrites enclosed within connective tissue capsules.

Separate Cells: Receptors physically separated from the first neuron in sensory pathway.

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20
Q

Free Nerve Endings:

A

Receptors composed of bare dendrites.

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21
Q

Encapsulated Nerve Endings:

A

Bare dendrites enclosed within connective tissue capsules.

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22
Q

Separate Cells:

A

Receptors physically separated from the first neuron in sensory pathway.

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23
Q

Somatic Sensory Pathways:

A

Pain and Temperature Pathway: Transmits signals from free nerve endings.
Touch, Pressure, Vibration,

Proprioception Pathway: Transmits signals from encapsulated nerve endings.

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24
Q

Pain and Temperature Pathway:

A

Transmits signals from free nerve endings.

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25
Q

Touch, Pressure, Vibration, Proprioception Pathway:

A

Transmits signals from encapsulated nerve endings.

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26
Q

Proprioception:

A

Definition: Position sense; awareness of body and its segments in space.

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27
Q

what are the types of somatic sensations?

A

tactile and proprioceptive

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28
Q

what are somatic sensations detected by?

A

specific receptors

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29
Q

list the tactile sensory receptors:

A

Touch – Merkel disc, Meissner corpuscle, Ruffini corpuscle

Pressure – Merkel disc, Ruffini corpuscle

Vibration – Meissner corpuscle, Pacinian corpuscle

Temperature – Free nerve endings

Pain – Free nerve endings

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30
Q

list the proprioceptive sensory receptors:

A

Position sense (muscles) – muscle spindles, tendon organs

Position sense (joints) – Ruffini corpuscles, Pacinian corpuscles

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31
Q

origins of somatic sensations

A

Tactile receptors in skin, proprioceptive receptors in muscles and joints.

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32
Q

Proprioceptive Receptors in Skeletal Muscles types and function:

A

Types: Muscle spindles, tendon organs.

Function: Monitor changes in muscle length and tension.

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33
Q

muscles spindles location and function:

A

Location: Encapsulated nerve endings within muscle belly.

Function: Respond to changes in muscle length.

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34
Q

tendon organs location and function:

A

Location: Encapsulated nerve endings within tendons.

Function: Respond to changes in muscle tension.

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35
Q

components of the SNS

A

Components: Includes sensory and motor pathways.

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36
Q

sensory pathways functions and direction:

A

Function: Transmit somatic sensory signals from peripheral receptors to the brain.

Direction: Upward transmission towards the brain.

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37
Q

motor pathways function and direction:

A

Function: Transmit motor signals from the brain to skeletal muscles.

Direction: Downward transmission from the brain.

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38
Q

what are located within the columns of white matter?

A

Signals that are transmitted up (sensory) and down (motor) the spinal cord and brain stem via specific tracts.

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39
Q

Tract Definition:

A

Bundle of axons transmitting signals in one direction within the central nervous system.

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40
Q

sensory signals direction and function:

A

Travel up the spinal cord.

Transmit sensory information to the brain.

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41
Q

motor signals direction and classification:

A

Travel down the spinal cord.

Transmit commands from the brain to muscles or glands.

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42
Q

what is sensory afferent?

A

Sensory afferent refers to nerve fibers or pathways that carry sensory information from sensory receptors (such as those in the skin, muscles, or organs) to the central nervous system (CNS), specifically to the brain or spinal cord.

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43
Q

sensory afferent classification:

A

classified as afferent neurons, which are nerve cells that carry signals towards the CNS.

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44
Q

what is motor efferent?

A

Motor efferent refers to nerve fibers or pathways that carry motor commands from the central nervous system (CNS), specifically from the brain or spinal cord, to muscles or glands.

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45
Q

how are motor efferents classified?

A

classified as efferent neurons, which are nerve cells that carry signals away from the CNS

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46
Q

Bottom - up (CNS)
Outside - IN (PNS)

A

sensory (afferent)

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47
Q

Top - Down (CNS)
Inside - Out (PNS)

A

Motor (efferent)

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48
Q

How are tracks typically named, and how does this aid in identifying their function?

A

Tracks are named based on their origin and termination. This naming convention helps distinguish sensory or ascending tracts from motor or descending tracts.

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49
Q

how can you determine whether a tract is sensory or motor?

A

Tracts starting in the spinal cord and ending in higher centers (like the thalamus) are sensory (ascending), while those starting in higher centers and ending in the spinal cord are motor (descending).

50
Q

how do tracts defer from nerves?

A

they are either sensory or motor. Never mixed

51
Q

How can you determine whether a tract is sensory or motor based on its name?

A

tracts are named based on their origin and destination. If the tract name indicates a path from the spinal cord to higher centers (e.g., thalamus), it’s sensory (ascending).

If it indicates a path from higher centers (e.g., cerebral cortex) to the spinal cord, it’s motor (descending).

52
Q

What does the name “Spinothalamic tract” suggest about its function?

A

The name indicates that the tract originates in the spinal cord and terminates in the thalamus. Therefore, it is an ascending sensory tract responsible for transmitting sensory information from the spinal cord to the thalamus.

53
Q

How is the function of the “Corticospinal tract” determined by its name?

A

The name implies that the tract starts in the cerebral cortex and terminates in the spinal cord.

As a result, it is a descending motor tract responsible for transmitting motor signals from the cerebral cortex to the spinal cord.

54
Q

How many neurons are involved in each somatic sensory pathway?

A

Each somatic sensory pathway consists of three neurons.

55
Q

Describe the function of the first-order neuron in a somatic sensory pathway.

A

The first-order neuron transmits signals from the sensory receptor to the spinal cord or brainstem.

56
Q

What is the role of the second-order neuron in a somatic sensory pathway?

A

The second-order neuron transmits signals from the spinal cord or brainstem to the thalamus.

57
Q

What does the third-order neuron do in a somatic sensory pathway?

A

The third-order neuron transmits signals from the thalamus to the primary somatosensory area in the parietal lobe of the cerebrum.

58
Q

How do second-order neurons behave in somatic sensory pathways?

A

Second-order neurons always decussate or cross over to the opposite side of the body in both pathways.

(Therefore, somatic sensory information from one side body always ends up on the opposite side of the brain)

59
Q

describe the 3-neuron relay system:

A

First order neuron: sensory receptor to spinal cord or brainstem

Second-order neuron: spinal cord or medulla oblongata to thalamus

Third-order neuron: transmit signals from the thalamus to the primary somatosensory area in the parietal lobe of the cerebrum.

60
Q

Somatic sensory pathways have ______

The _____ in the pathway crosses to the opposite side of the body

A

Therefore:

Somatic sensory pathways have 3 neurons

The 2nd neuron in the pathway crosses to the opposite side of the body

61
Q

what are the two main somatic sensory pathways?

A

Anterolateral (spinothalamic) pathway

Posterior column pathway

62
Q

Anterolateral (spinothalamic) pathway

A

Carries signals related to temperature and pain

Uses tracts in the anterior and lateral columns

63
Q

Posterior column pathway

A

Carries signals related to touch, pressure, vibration, and proprioception

Uses tracts in the posterior column

64
Q

What are the two main somatic sensory pathways, and what types of sensations do they transmit?

A

The anterolateral pathway: Transmits signals from free nerve endings, leading to perceptions of pain and temperature.

The posterior column pathway: Transmits signals from encapsulated nerve endings, leading to perceptions of touch, pressure, vibration, and proprioception.

65
Q

How are the tracts in the spinal cord named for each somatic sensory pathway, and what sensations do they carry?

A

The anterolateral pathway: Utilizes tracts in the anterior and lateral columns, transmitting sensations of pain and temperature.

The posterior column pathway: Utilizes tracts in the posterior column, transmitting sensations of touch, pressure, vibration, and proprioception.

66
Q

Describe the crossing over of neurons in the somatic sensory pathways.

A

In both pathways, the first motor neuron crosses over to the opposite side of the body. The lower motor neuron then carries the signal up the pathway to the brain.

67
Q

What is the structure of the anterolateral pathway?

A

The first-order neuron enters the spinal cord via the posterior root of a spinal nerve.

It relays its sensory signal to a second-order neuron in the posterior horn of the spinal cord.

The axon of the second-order neuron crosses over to the opposite side of the body and ascends through the spinal cord and brainstem to the thalamus in the spinal thalamic tract.

68
Q

What happens in the thalamus regarding the anterolateral pathway?

A

In the thalamus, the second-order neuron relays the sensory signal to a third-order neuron, whose axon transmits the signal to the primary somatosensory area.

69
Q

How does the structure of the posterior column pathway compare to the anterolateral pathway?

A

In the posterior column pathway, the first-order neuron also enters the spinal cord via the posterior root of a spinal nerve.

However, unlike the anterolateral pathway, the first-order neuron does not relay its signal to second-order neurons in the spinal cord.

70
Q

What does the axon of the first-order neuron in the posterior column pathway do instead of relaying signals to second-order neurons?

A

The axon of the first-order neuron passes into a tract in the posterior column on the same side and proceeds up the spinal cord to the brainstem.

71
Q

How does the crossing over of neurons occur in the posterior column pathway?

A

The axon of the second-order neuron in the brainstem crosses over to the opposite side of the body.

This crossing over occurs because second-order neurons are responsible for crossover in somatic sensory pathways.

72
Q

What happens in the thalamus regarding the posterior column pathway?

A

In the thalamus, the second-order neuron relays the sensory signal to a third-order neuron, whose axon then transmits the signal to the primary somatosensory area.

73
Q

anterolateral sensations:

A

temperature, pain - free nerve endings

74
Q

posterior column sensations:

A

touch, pressure, vibration, proprioception - Encapsulated nerve endings

75
Q

anterolateral 1st - 2nd order neuron synapse:

A

spinal cord

76
Q

posterior column 1st - 2nd order neuron synapse:

A

medulla oblongata

77
Q

anterolateral spinal cord tract:

A

contralateral spinothalamic tract (2nd order neuron)

78
Q

posterior column spinal cord tract

A

ipsilateral posterior tract (1st order neuron)

79
Q

How many somatic motor pathways are there, and what is their structure?

A

There are two main somatic motor pathways, each consisting of two neurons.

80
Q

main somatic motor pathways (2)

A

Upper motor neurons transmit signals from the primary motor area in the frontal lobe of the cerebrum to the spinal cord.

Lower motor neurons transmit signals from the spinal cord to the skeletal muscle.

80
Q

What is the role of upper motor neurons in somatic motor pathways?

A

Upper motor neurons transmit signals from the primary motor area in the frontal lobe of the cerebrum to the spinal cord.

80
Q

Describe the function of lower motor neurons in somatic motor pathways.

A

Lower motor neurons transmit signals from the spinal cord to the skeletal muscle.

80
Q

How do upper motor neurons behave in somatic motor pathways?

A

Upper motor neurons always decussate or cross over to the opposite side of the body in both somatic motor pathways.

(Therefore, motor signals originating on one side of the brain always end up on the opposite side of the body)

81
Q

somatic motor pathways consist of a _____ relay system.

A

2 - neuron

82
Q

describe the somatic motor pathway relay system:

A

Upper motor neuron: primary motor area - spinal cord

Lower motor neuron: spinal cord - skeletal muscle

83
Q

Therefore:

Somatic motor pathways have ____
The _____ in the pathway crosses to the opposite side of the body

A

Therefore:

Somatic motor pathways have 2 neurons

The 1st neuron in the pathway crosses to the opposite side of the body

84
Q

How can somatic motor pathways be classified?

A

direct pathways originating in the cerebral cortex and indirect pathways originating in the brainstem.

85
Q

How do upper motor neurons cross over in the two main direct somatic motor pathways?

A

Upper motor neurons always cross over, but the location of crossing over differs.

86
Q

what percent of neurons cross over in the brain stem in the lateral corticospinal tract?

A

90% cross over in the brainstem at the decussation of the pyramids.

87
Q

in the anterior corticospinal tract what remaining percent cross over at their target spinal cord segment?

A

10%

88
Q

What is the significance of the decussation of the pyramids?

A

The decussation of the pyramids is the site at which 90% of upper motor neurons decussate in the brainstem, visible as a meshwork on the surface of the medulla oblongata.

89
Q

what are somatic motor pathways classified as?

A

direct or indirect

90
Q

Direct motor pathways

A

carry signals originating in the cerebral cortex

91
Q

Indirect motor pathways

A

carry signals originating in the brain stem

92
Q

where do all somatic motor pathways use tracts?

A

in the anterior and lateral columns

93
Q

The main direct motor pathway

A

corticospinal pathway

94
Q

Where do 90% of upper motor neurons decussate?

A

90% of upper motor neurons decussate in the medulla oblongata.

95
Q

What pathway do these decussated upper motor neurons follow?

A

They travel down the contralateral side of the spinal cord, specifically through the lateral corticospinal tract.

96
Q

How do 10% of upper motor neurons travel in the spinal cord?

A

They travel down the ipsilateral side of the spinal cord.

97
Q

What pathway do these 10% of upper motor neurons follow?

Where do these upper motor neurons decussate?

A

They travel through the anterior corticospinal tract.

They decussate at their target spinal segment.

98
Q

Describe the path of the upper motor neuron (90%)

A

The upper motor neuron originates in the primary motor area.

Its axon travels down the brainstem until it reaches the medulla oblongata.

At the medulla oblongata, it crosses over before descending the spinal cord in the contralateral lateral corticospinal tract.

99
Q

What happens at the target spinal cord segment?

A

At the target spinal cord segment, the axon leaves the tract and relays the signal to a lower motor neuron.

100
Q

How does the signal reach skeletal muscle?

A

The axon of the lower motor neuron exits the spinal cord via the anterior root and transmits the signal to skeletal muscle.

101
Q

Describe the path of the upper motor neuron in this pathway. (10%)

A

The upper motor neuron originates in the primary motor area.

Its axon travels down the ipsilateral brainstem and spinal cord in the anterior corticospinal tract.

102
Q

What occurs at the target spinal cord segment in this pathway?

A

At the target spinal cord segment, the upper motor neuron leaves the tract and crosses over.

103
Q

Where is the lower motor neuron located in this pathway, and what does it do?

A

The lower motor neuron is located in the contralateral anterior horn of the spinal cord. It exits the spinal cord via the anterior root and transmits the signal to skeletal muscle.

104
Q

What can form within the central canal of the spinal cord?

A

Syringomyelia

A fluid-filled (CSF) cyst can form within the central canal of the spinal cord.

105
Q

What are the symptoms associated with a spinal cord cyst?

A

dissociated sensory loss primarily affecting the upper limbs, pain/temperature sensation affected while touch/pressure/vibration/proprioception remain unaffected, muscle weakness in both upper and lower limbs, pain, and autonomic symptoms.

106
Q

What happens if a spinal cord cyst is left untreated?

A

the cyst generally enlarges over time, leading to increased nervous system dysfunction and disability.

107
Q

What is usually required for the treatment of a spinal cord cyst?

A

Surgical treatment, which may involve addressing the cyst and/or its underlying cause, is usually required.

108
Q

BROWN-SÉQUARD SYNDROME

A

Caused by an injury to one half of the spinal cord (hemi section)

109
Q

What areas of the spinal cord does the lesion affect?

BROWN-SÉQUARD SYNDROME

A

ipsilateral anterior, lateral, and posterior columns of the spinal cord.

110
Q

Where are the cell bodies of the lower motor neurons located in both somatic sensory pathways?

A

The cell bodies of the lower motor neurons are in the anterior horn of the spinal cord.

111
Q

Where are the cell bodies of the first-order neurons located in both somatic sensory pathways?

A

The cell bodies of the first-order neurons are in the posterior root ganglion.

112
Q

Where are the axons of the lower motor neurons located in both somatic sensory pathways?

A

The axons of the lower motor neurons are in the anterior root.

113
Q

Where are the axons located in the first-order neurons in both somatic sensory pathways?

A

The axons in the first-order neurons are in the posterior root.

114
Q

What tracts are used in the somatic motor pathways?

A

The corticospinal tracts are used, with an anterior corticospinal tract in the anterior column and a lateral corticospinal tract in the lateral column.

115
Q

Which tracts are utilized in the somatic sensory pathways?

A

The spinothalamic tracts are utilized in the anterior and lateral somatic sensory pathways, spanning the anterior and lateral columns.

116
Q

How are signals related to pressure, vibration, and proprioception transmitted in somatic sensory pathways?

A

These signals are transmitted via the posterior columns’ somatic sensory pathway, which uses tracts in the posterior columns. The axons in these tracts are first-order neurons in the pathway originating on the same side of the body.

117
Q

How are signals related to pain and temperature transmitted in somatic sensory pathways?

A

Signals related to pain and temperature are transmitted via the anterolateral somatic sensory pathway, which uses tracts in the anterior and lateral columns. The axons in these tracts are second-order neurons in the pathway originating on the opposite side of the body.

Anatomy (34 decks)

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