Lecture 17: Spinal Cord 2

Question 1

Three Types of Connective Tissue Layers in Spinal Nerves

Answer 1

Epineurium,
Perineurium,
Endoneurium

Question 2

Epineurium

Answer 2

Outer layer,

Dense network of collagen fibers

Question 3

Perineurium

Answer 3

Middle layer,

Divides nerve into fascicles (axon bundles)

Question 4

Endoneurium

Answer 4

Inner layer,

Surrounds individual axons

Question 5

Branches

Answer 5

Pathways to body areas

Question 6

Rami Communicantes and Sympathetic Nerves

Answer 6

Pathways for visceral sensory neurons,

Part of ANS

Question 7

Dorsal Ramus

Answer 7

Back of body pathway,

Motor and sensory neurons going to and from back of body

Question 8

Ventral Ramus

Answer 8

Access from front to spinal cord pathway,

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

Question 9

Nerve

Answer 9

Bundle of axons

Question 10

Dermatome

Answer 10

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

Question 11

Nerve Plexuses

Answer 11

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

Question 12

4 Major Plexuses of Ventral Rami

Answer 12

Cervical Plexus,
Brachial Plexus,
Lumbar Plexus,
Sacral Plexus

Question 13

Cervical Plexus

Answer 13

Includes ventral rami of spinal nerves C1-C5,

Innervates neck, thoracic cavity, diaphragmatic muscles

Question 14

Major Nerve of Cervical Plexus

Answer 14

Phrenic Nerve

Question 15

Phrenic Nerve

Answer 15

Controls diaphragm

Question 16

Brachial Plexus

Answer 16

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

Question 17

Lumbosacral Plexus

Answer 17

Nerves that emerge innervate pelvis and lower extremities,

Sciatic nerve is biggest in body

Question 18

How Many Sensory Neurons Are There?

Answer 18

10 million

Question 19

What Do Sensory Neurons Do?

Answer 19

Deliver information to CNS

Question 20

How Many Motor Neurons Are There?

Answer 20

500,000

Question 21

What Do Motor Neurons Do?

Answer 21

Deliver commands to peripheral effectors

Question 22

How Many Interneurons Are There?

Answer 22

20 billion mostly in CNS

Question 23

What Do Interneurons Do?

Answer 23

Interpret, plan, and coordinate signals in and out

Functional groups

Question 24

Functional Groups =

Answer 24

Neuronal Pools

Question 25

Neuronal Pools

Answer 25

Functional groups of interconnected neurons, | Limited input sources and output destinations

Question 26

5 Patterns of Neural Circuits in Neuronal Pools

Answer 26

``` Divergence, Convergence, Serial Processing, Parallel Processing, Reverberation ```

Question 27

Divergence

Answer 27

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

Question 28

Convergence

Answer 28

Brings input from many sources to single neuron, | Diaphragm

Question 29

Serial Processing

Answer 29

Moves information in single line

Question 30

Parallel Processing

Answer 30

Moves same information along several paths simultaneously

Question 31

Reverberation

Answer 31

Positive feedback mechanism, | Functions until inhibited

Question 32

Spinal Reflexes

Answer 32

Automatic responses coordinated within spinal cord, | Occur through interconnected sensory neurons, motor neurons, and interneurons

Question 33

First Step In A Spinal Reflex

Answer 33

Arrival of stimulus, activation of receptor

Question 34

Second Step In A Spinal Reflex

Answer 34

Activation of sensory neuron

Question 35

Third Step In A Spinal Reflex

Answer 35

Information processing by postsynaptic cell

Question 36

Fourth Step In A Spinal Reflex

Answer 36

Activation of motor neuron

Question 37

Fifth Step In A Spinal Reflex

Answer 37

Response of peripheral effector

Question 38

Innate Reflexes

Answer 38

Genetically or developmentally determined

Question 39

Acquired Reflexes

Answer 39

Learned

Question 40

Somatic Reflexes

Answer 40

Control skeletal muscle contractions

Question 41

Visceral Reflexes

Answer 41

Control actions of smooth and cardiac muscles and glads

Question 42

Monosynaptic Reflexes

Answer 42

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

Question 43

Polysynaptic Reflexes

Answer 43

Multiple synapses

Question 44

Cranial Reflexes

Answer 44

Processing in the brain

Question 45

Spinal Reflexes

Answer 45

Processing to the spinal cord

Question 46

Stretch Reflex

Answer 46

Monosynaptic reflex

Question 47

Muscle Spindle

Answer 47

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

Question 48

Example of Stretch Reflex

Answer 48

Patellar reflex

Question 49

Extrafusal Fiber in Muscle Spindle

Answer 49

Effector tissue

Question 50

Intrafusal Fiber in Muscle Spindle

Answer 50

Receptor

Question 51

Tendon Reflex

Answer 51

Protective reflex, | Act by inhibiting motor neuron acting on muscle

Question 52

What Do Tendon Reflexes Protect Skeletal Muscles From?

Answer 52

Developing too much tension, | Tearing or breaking tendons

Question 53

Flexor Reflex

Answer 53

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

Question 54

Reciprocal Inhibition

Answer 54

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

Question 55

Types of Reflex Arcs

Answer 55

Ipsilateral, | Crossed Extensor Reflex

Question 56

Ipsilateral Reflex Arc

Answer 56

Occur on same side of body as stimulus

Question 57

Crossed Extensor Reflexes

Answer 57

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