Lecture 17: Spinal Cord 2 Flashcards

1
Q

Three Types of Connective Tissue Layers in Spinal Nerves

A

Epineurium,
Perineurium,
Endoneurium

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2
Q

Epineurium

A

Outer layer,

Dense network of collagen fibers

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3
Q

Perineurium

A

Middle layer,

Divides nerve into fascicles (axon bundles)

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4
Q

Endoneurium

A

Inner layer,

Surrounds individual axons

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5
Q

Branches

A

Pathways to body areas

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6
Q

Rami Communicantes and Sympathetic Nerves

A

Pathways for visceral sensory neurons,

Part of ANS

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7
Q

Dorsal Ramus

A

Back of body pathway,

Motor and sensory neurons going to and from back of body

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8
Q

Ventral Ramus

A

Access from front to spinal cord pathway,

Motor and sensory neurons going to and from body wall and limbs

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9
Q

Nerve

A

Bundle of axons

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10
Q

Dermatome

A

Specific bilateral region of skin from which sensory information is carried by a pair of spinal nerves,
Each spinal nerve has its own,
Some overlap

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11
Q

Nerve Plexuses

A

Joining of rami that give off branches,
Complex, interwoven networks of nerve fibers,
Formed from blended fibers of ventral rami of adjacent spinal nerves

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12
Q

4 Major Plexuses of Ventral Rami

A

Cervical Plexus,
Brachial Plexus,
Lumbar Plexus,
Sacral Plexus

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13
Q

Cervical Plexus

A

Includes ventral rami of spinal nerves C1-C5,

Innervates neck, thoracic cavity, diaphragmatic muscles

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14
Q

Major Nerve of Cervical Plexus

A

Phrenic Nerve

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15
Q

Phrenic Nerve

A

Controls diaphragm

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16
Q

Brachial Plexus

A

Includes ventral rami of spinal nerves C5-T1,
Nerves that emerge from plexus innervate pectoral girdle and upper limbs,
Axillary area

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17
Q

Lumbosacral Plexus

A

Nerves that emerge innervate pelvis and lower extremities,

Sciatic nerve is biggest in body

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18
Q

How Many Sensory Neurons Are There?

A

10 million

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19
Q

What Do Sensory Neurons Do?

A

Deliver information to CNS

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20
Q

How Many Motor Neurons Are There?

A

500,000

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21
Q

What Do Motor Neurons Do?

A

Deliver commands to peripheral effectors

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22
Q

How Many Interneurons Are There?

A

20 billion mostly in CNS

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23
Q

What Do Interneurons Do?

A

Interpret, plan, and coordinate signals in and out

Functional groups

24
Q

Functional Groups =

A

Neuronal Pools

25
Q

Neuronal Pools

A

Functional groups of interconnected neurons,

Limited input sources and output destinations

26
Q

5 Patterns of Neural Circuits in Neuronal Pools

A
Divergence,
Convergence,
Serial Processing,
Parallel Processing,
Reverberation
27
Q

Divergence

A

Spreads stimulation to many neurons or neuronal pools in CNS (One to many)

28
Q

Convergence

A

Brings input from many sources to single neuron,

Diaphragm

29
Q

Serial Processing

A

Moves information in single line

30
Q

Parallel Processing

A

Moves same information along several paths simultaneously

31
Q

Reverberation

A

Positive feedback mechanism,

Functions until inhibited

32
Q

Spinal Reflexes

A

Automatic responses coordinated within spinal cord,

Occur through interconnected sensory neurons, motor neurons, and interneurons

33
Q

First Step In A Spinal Reflex

A

Arrival of stimulus, activation of receptor

34
Q

Second Step In A Spinal Reflex

A

Activation of sensory neuron

35
Q

Third Step In A Spinal Reflex

A

Information processing by postsynaptic cell

36
Q

Fourth Step In A Spinal Reflex

A

Activation of motor neuron

37
Q

Fifth Step In A Spinal Reflex

A

Response of peripheral effector

38
Q

Innate Reflexes

A

Genetically or developmentally determined

39
Q

Acquired Reflexes

A

Learned

40
Q

Somatic Reflexes

A

Control skeletal muscle contractions

41
Q

Visceral Reflexes

A

Control actions of smooth and cardiac muscles and glads

42
Q

Monosynaptic Reflexes

A

One synapse,
Least delay between sensory input and motor output,
Completed in 20-40 milliseconds

43
Q

Polysynaptic Reflexes

A

Multiple synapses

44
Q

Cranial Reflexes

A

Processing in the brain

45
Q

Spinal Reflexes

A

Processing to the spinal cord

46
Q

Stretch Reflex

A

Monosynaptic reflex

47
Q

Muscle Spindle

A

Receptor for stretch reflexes,
Small, specialized intrafusal muscle fibers,
Surrounded by extrafusal muscle fibers (normal muscle fibers)

48
Q

Example of Stretch Reflex

A

Patellar reflex

49
Q

Extrafusal Fiber in Muscle Spindle

A

Effector tissue

50
Q

Intrafusal Fiber in Muscle Spindle

A

Receptor

51
Q

Tendon Reflex

A

Protective reflex,

Act by inhibiting motor neuron acting on muscle

52
Q

What Do Tendon Reflexes Protect Skeletal Muscles From?

A

Developing too much tension,

Tearing or breaking tendons

53
Q

Flexor Reflex

A

Withdrawal reflex,
Move body part away from stimulus (pain or pressure),
Inhibit antagonist muscle to increase speed of contraction

54
Q

Reciprocal Inhibition

A

For flexor reflex to work the stretch reflex of antagonist (extensor) muscle must be inhibited (reciprocal inhibition) by interneurons in spinal cord

55
Q

Types of Reflex Arcs

A

Ipsilateral,

Crossed Extensor Reflex

56
Q

Ipsilateral Reflex Arc

A

Occur on same side of body as stimulus

57
Q

Crossed Extensor Reflexes

A

Involve a contralateral reflex arc,
Occur on side opposite of stimulus,
Occur simultaneously, coordinated with flexor reflex