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Unit 2 > BIOMED 10/15a SC Anatomy 1 > Flashcards

BIOMED 10/15a SC Anatomy 1 Flashcards

1
Q

Spinal cord

A

part of CNS that profusely connects to the PNS - longitudinal

  • virtual two-way link between the brain and the periphery
  • connects to the periphery via 31 spinal nerves
  • diameter changes in size depending on the part of the body that it innervates
  • runs from foramen magnum to L2
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2
Q

Do spinal cord levels all match the vertebral levels?

A

no - the spinal cord ends at L2 and that’s when nerves start to track off from them

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3
Q

Transverse orientation of the spinal cord

A
  • Dorsal (balloon on nerve)
  • Ventral = front
  • Central Canal
  • Grey Matter
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4
Q

what does the grey matter of the spinal cord consist of?

A
  • rexed’s laminae
  • ventral horn: motor neurons
  • dorsal horn: sensory neurons
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5
Q

what is rexed’s lamina?

A

there are 10 different lamina
each lamina has distinct cells
there is a gradient along the dorsal (sensory), middle (integration between sensory and motor), ventral (motor)

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6
Q

white matter tracts of the spinal cord

A

carry axons that travel from the brain to the spinal cord, or PNS to CNS no cell bodies, primarily axons

  1. posterior Funiculus
  2. Lateral Funiculus
  3. Anterior Funiculus
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7
Q

what is the significance of the ratio of grey matter to white matter in the spinal cord?

A
  • Thoracic spine has pointed structures called lateral horns and smaller grey matter -> sympathetic neurons
  • Cervical and Lumbar spine have enlarged grey matter -> parasympathetic neurons
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8
Q

how is the spinal cord connected to the periphery?

A

Interior to exterior

  1. spinal nerve
  2. ramus
  3. plexus
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9
Q

what is the spinal nerve composed of?

A

dorsal and ventral roos join to form a spinal nerve

-it has both sensory and motor impacts

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10
Q

what is the ramus?

A
  • split of the spinal nerve
  • dorsal supplies the muscle and skin of the back
  • ventral forms the plexus (brachial and lumbar)
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11
Q

what is the plexus?

A
  • there are brachial and lumbosacral plexuses
  • they supply the UEs and LEs
  • formed from the ventral rami
  • have both motor and sensory axons and neurons
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12
Q

peripheral spinal nerve structure

A

Most internal to external

  1. Endoneurium
  2. Perineurium
  3. Epineurium
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13
Q

what is the endoneurium?

A

it covers bundles of multiple axons that are surrounded by schwann cells

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14
Q

what is the perineurium?

A

multiple bundles of axons surrounded by the endoneurium are encapsulated into a fascicle called the perineurium

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15
Q

what is the epineurium?

A

epineurium encloses all of the fascicles of endoneurium and perineurium to create the peripheral nerve structure

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16
Q

what is the purpose of sensory receptors?

A

help in converting 1 form of energy to electrical signal

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17
Q

what does a receptor need in order to complete the transfer of energy appropriately?

A
  1. stimulus transduction
  2. receptor specificity
  3. location of receptor
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18
Q

what is the process of stimulus transduction?

A
  • process by which stimulus is converted into an electrical signal
    1. stimulus from environment
    2. altered membrane conductance
    3. altered membrane potential
    4. altered action potential frequency
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19
Q

significance of receptor specificiity

A

receptors only respond to specific type of stimulus

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20
Q

Spinal nerves have two different components

A
  1. sensory

2. motor

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21
Q

how do sensory nerves transfer information afferently to the cns?

A
  1. there is a receptor that is attached to a sensory afferent nerve.
  2. the receptor gets the stimulus and travels to the dorsal root ganglia (bipolar)
  3. no synapse on dorsal root ganglia
  4. enters the spinal cord
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22
Q

once the axon of the sensory nerve enters the spinal cord, what does it do?

A

It can do any of the three or all of the three:

  1. enters at the level of the spinal cord, innervates/synapses the interneuron right there
  2. travels up spinal cord to somatosensory cortex
  3. synapses on other segments of the spinal cord
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23
Q

how do motor nerves transfer information Efferently to muscles?

A
  1. neurons sit in anterior horn of spinal cord
  2. axons leave through the anterior/ventral root
  3. skeletal muscles are innervated
24
Q

what are the different anterior horn cells?

A
  • part of the final common pathway
  • neurons whose axons project onto the muscles
  • all heavily myelinated
    1. alpha (MOST)
    2. gamma (middle)
    3. beta (least)
25
Q

what is a motor unit?

A
  • single alpha motor neuron and all the muscle fibers that it innervates
  • single muscle fiber receives info from a single motor neuron
  • all muscles in a motor unit contract together when neuron fires
  • ALL OR NONE
  • to create more muscle force, recruit more motor units
  • multiple motor neurons come out of a single spinal segment
26
Q

what is a myotome?

A
  • muscle served by a single spinal nerve root emerging from a spinal segment
  • consists of multiple motor units
27
Q

What is a dermatome?

A

-area of skin innervated by a single ventral spine root

28
Q

sclerotome

A

connective tissue structures innervated by a specific spinal nerve

29
Q

what are different ways to classify receptors by location?

A
  1. exteroceptors
  2. interoceptors
  3. proprioceptors
30
Q

what is the significance of an exteroceptor?

A
  • sensitive to stimuli arising from outside of the body

- most common in skin (epidermis, dermis, and some in hypodermis)

31
Q

what are the different types of exteroceptors?

A
  1. merkels disc - light touch
  2. meissner’s corpuscle - dermis - light pressure
  3. ruffinis organs - deep pressure
  4. pacinean corpuscle - deep pressure
  5. free nerve endings - pain and temperature
32
Q

what are the two main concepts of exteroceptors?

A
  1. receptive field

2. adaptation

33
Q

what is a receptive field?

A

exteroceptor concept:
area of the skin that receives input can be either sharp or diffuse
2 point discrimination changes with a patient - need to do sensory re-education

34
Q

what is adaptation with an exteroceptor?

A

change in response to a specific stimulus

  1. rapid/phasic - specific
    - meissner’s corpuscles
    - pacinean corpuscle
  2. slow/tonic - diffuse
    - merkel’s cells
    - ruffini’s endings
35
Q

what is an interoceptor?

A

visceroceptor

-from internal viscera

36
Q

what is a proprioceptor?

A

Monitors degree of stretch in skeletal muscles, tendons, joints and ligaments
relay information to cerebrum, cerebellum, and spinal reflex arcs

37
Q

what 3 receptors respond to proprioception?

A
  1. muscle spindles
  2. golgi tendon organs
  3. joint kinesthetic receptors
38
Q

what do muscle spindles do?

A

respond to stretch and rate of change of muscle length

  1. intrafusal fibers
    - nuclear bag fibers
    - nuclear chain fibers
  2. extrafusal fibers
39
Q

intrafusal muscle fibers***

A

sensory organs

  1. nuclear bag
    - static > muscle length
    - dynamic > rate of change of muscle length
    - group Ia dynamic afferent nerves innervate all static and dynamic
  2. nuclear chain
    - static > muscle length
    - group II afferent fibers for just static
40
Q

golgi tendon organ

A
  • near muscle tendon junction
  • receptor that detects tension
  • collagen detects stretch
  • have a high threshold for stimulation
  • goal is to prevent any muscle/tendon issue
41
Q

extrafusal muscle fibers

A

skeletal muscles

42
Q

transduction with pacinean corpuscle

A
  • pacinean corpuscle is in the skin and detects pressure
  • pressure deforms lamellae of receptors
  • receptors at the end have axons that now receives a changed mechanical input
  • axons have ion channels that are mechanically gated
  • mechanically gated ion channels open and change membrane conductance
  • Sodium enters and causes cell to depolarize
  • get EPSP and it reaches threshold
  • AP travels down axon as converted electrical energy (relayed by afferent fibers of spinal cord)
43
Q

how are different types of sensory information detected and relayed?

A

different sensory functions have:

  1. specific receptor types
  2. afferent axon type
  3. varying axon diameter
  4. varying conduction velocity
44
Q

how do joint kinesthetic receptors impact proprioceptor receptors?

A
  • tells us about the position of the joint in space
    1. monitor stretch in synovial joints
    2. send info to the somatosensory cortex, cerebellum, and spinal reflex arcs
    3. sense movement or/and joint position
45
Q

what is the purpose of the thalamus?

A

-2 located at the base of the brain in the diancephalon
-regulate all of the input going towards the cortex from anywhere
“gate keeper”

46
Q

what is the somatosensory cortex?

A

receives all sensory inputs

47
Q

ascending tracts

A

carry info from periphery to the cortex

  • contralateral somatosensory cortex
    1. DCML
    2. ALS
48
Q

DCML inputs/main sensations

A 
Dorsal Column Medial Leminiscal Tract/Dorsal Column
-Tactile
-Proprioception
-Vibration
ASCENDING
49
Q

DCML Pathway

A
  1. First order neuron (bipolar) axon that is afferent has proprioceptors or mechanoreceptors and detects a stimulus then enters the dorsal root ganglion and dorsal columns(posterior funiculus); does NOT synapse
  2. second axon of the first order neuron travels up to the medulla oblongata where there are two nuclei and synapses there
  3. Second order neuron sits in either of the below nuclei in the medulla oblongata and its axons cross over and travel to the thalamus (VPL) where they synapse
    - nucleus cuneatis
    - nucleus grasilis
  4. Third order neuron goes from the thalamus to the primary somatosensory cortex
50
Q

ALS inputs/main sensations

A 
Anterolateral System/Spinothalamic Tract/Venterolateral Pathways
-Pain
-Itch
-Temperature
(older than DCML)
ASCENDING
51
Q

similarities amongst DCML and ALS

A
  • project to contralateral thalamus and somatosensory cortex
  • Three main neurons
    1. first order: in the dorsal root ganglion
    2. second order: varies
    3. third order: in the thalamus (ventroposterolateral - VPL nucleus)
52
Q

ALS Pathway

A
  1. First order neuron (bipolar) axon that is afferent has nociceptors or thermoreceptors and detects a stimulus then enters the dorsal root ganglion
  2. second axon of the first order neuron synapses on second order neuron of ALS that sits in the dorsal horn of the spinal cord
  3. Second order neurons axons cross over and ascend in the anterolateral funiculus to the thalamus where they synapse
  4. Third order neuron goes from the thalamus to the primary somatosensory cortex
53
Q

what are the axons of the second order neurons called in the DCML pathway?

A

decussated medial leminiscus

54
Q

somatotopic organization for DCML

A 
specific order in which the fibers from different body parts are ascending
Fasiculus Grasilis
-most medial = LE
Fasiculus Cuneatus
-most lateral = UE
55
Q

somatotopic organization for ALS**??

A
  • Most lateral = LE

- Most medial = UE

Unit 2 (31 decks)

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