chapter 13

Question 1

• Contains axons of motor neurons

Answer 1

Ventral root

Question 2

Contains axons of sensory neurons

Answer 2

Dorsal root

Question 3

Contain cell bodies of sensory neurons

Answer 3

Dorsal root ganglia

Question 4

Carry both afferent (sensory) and efferent (motor) fibers

Answer 4

Mixed Nerves

Question 5

Outer layer of spinal cord

Answer 5

Dura mater

Question 6

Middle meningeal layer

Answer 6

Arachnoid mater

Question 7

Inner meningeal layer

Answer 7

Pia mater

Question 8

Functions of the spinal meninges include:

Answer 8

• Protecting spinal cord
• Carrying blood supply
• Continuous with cranial meninges

Question 9

• Viral or bacterial infection of meninges

Answer 9

Meningitis

Question 10

Specialized membranes isolate spinal cord from

surroundings

Answer 10

Spinal Meninges

Question 11

Carries dissolved gases, nutrients, and wastes

Answer 11

Cerebrospinal Fluid (CSF)

Question 12

Major categories of disease detected in CSF

Answer 12

• Meningeal infections
• Subarachnoid hemorrhage
• CNS malignancy
• Demyelinating disease

Question 13

• Is the innermost meningeal layer
• Is a mesh of collagen and elastic fibers
• Is bound to underlying neural tissue

Answer 13

The Pia Mater

Question 14

• Is superficial

* Contains myelinated and unmyelinated axons

Answer 14

White matter

Question 15

• Surrounds central canal of spinal cord
• Contains neuron cell bodies, neuroglia, unmyelinated
axons
• Has projections (gray horns)

Answer 15

Gray matter

Question 16

• Dorsal (posterior)

* Connect to peripheral receptors

Answer 16

Sensory nuclei

Question 17

• Ventral (anterior)

* Connect to peripheral effectors

Answer 17

Motor nuclei

Question 18

The cell bodies of neurons form functional groups

called

Answer 18

nuclei

Question 19

Spinal Cord Summary:

Answer 19

• Spinal cord has a narrow central canal
• Surrounded by gray matter
• Containing sensory and motor nuclei
• Sensory nuclei are dorsal
• Motor nuclei are ventral

Question 20

• Interconnecting branches of spinal nerves

* Surrounded by connective tissue sheaths

Answer 20

Peripheral Nerves

Question 21

• Regional loss of sensory or motor function

* Due to trauma or compression

Answer 21

Peripheral Neuropathy

Question 22

The Four Major Plexuses of

Ventral Rami:

Answer 22

1. Cervical plexus
2. Brachial plexus
3. Lumbar plexus
4. Sacral plexus

Question 23

• Includes ventral rami of spinal nerves C1–C5
• Innervates neck, thoracic cavity, diaphragmatic
muscles
• Major nerve
• Phrenic nerve (controls diaphragm)

Answer 23

The Cervical Plexus

Question 24

• Includes ventral rami of spinal nerves C5–T1
• Innervates pectoral girdle and upper limbs
• Nerves that form brachial plexus originate from:
• Superior, middle, and inferior trunks
• Large bundles of axons from several spinal nerves
• Lateral, medial, and posterior cords
• Smaller branches that originate at trunks

Answer 24

The Brachial Plexus

Question 25

* Includes ventral rami of spinal nerves T12–L4 * Major nerves * Genitofemoral nerve * Lateral femoral cutaneous nerve * Femoral nerve

Answer 25

The Lumbar Plexus

Question 26

``` • Includes ventral rami of spinal nerves L4–S4 • Major nerves • Pudendal nerve • Sciatic nerve • Two branches of the sciatic nerve 1. Fibular nerve 2. Tibial nerve ```

Answer 26

The Sacral Plexus

Question 27

* About 10 million | * Deliver information to CNS

Answer 27

Sensory neurons

Question 28

* About 1/2 million | * Deliver commands to peripheral effectors

Answer 28

Motor neurons

Question 29

About 20 billion | • Interpret, plan, and coordinate signals in and out

Answer 29

Interneuron

Question 30

``` A mechanism for spreading stimulation to multiple neurons or neuronal pools in the CNS ```

Answer 30

Divergence

Question 31

A mechanism for providing input to a single neuron from multiple sources

Answer 31

Convergence

Question 32

A mechanism in which neurons or pools work sequentially

Answer 32

Serial | processing

Question 33

A mechanism in which neurons or pools process the same information simultaneously

Answer 33

Parallel processing

Question 34

A positive feedback | mechanism

Answer 34

Reverberation

Question 35

• Automatic responses coordinated within spinal cord • Through interconnected sensory neurons, motor neurons, and interneurons • Produce simple and complex reflexes

Answer 35

Reflexes

Question 36

* Rapid, automatic responses to specific stimuli * Basic building blocks of neural function * One neural reflex produces one motor response

Answer 36

Neural Reflexes

Question 37

``` • The wiring of a single reflex • Beginning at receptor • Ending at peripheral effector • Generally opposes original stimulus (negative feedback) ```

Answer 37

Reflex arc

Question 38

• Five Steps in a Neural Reflex

Answer 38

* Step 1: Arrival of stimulus, activation of receptor * Physical or chemical changes * Step 2: Activation of sensory neuron * Graded depolarization * Step 3: Information processing by postsynaptic cell * Triggered by neurotransmitters * Step 4: Activation of motor neuron * Action potential * Step 5: Response of peripheral effector * Triggered by neurotransmitters

Question 39

• Four Classifications of Reflexes

Answer 39

1. By early development 2. By type of motor response 3. By complexity of neural circuit 4. By site of information processing

Question 40

Basic neural reflexes | • Formed before birth

Answer 40

Innate reflexes

Question 41

* Rapid, automatic | * Learned motor patterns

Answer 41

Acquired reflexes

Question 42

• Involuntary control of nervous system • Superficial reflexes of skin, mucous membranes • Stretch or deep tendon reflexes (e.g., patellar, or “knee-jerk,” reflex) • Visceral reflexes (autonomic reflexes

Answer 42

• Somatic reflexes

Question 43

• Control systems other than muscular system

Answer 43

Visceral reflexes (autonomic reflexes)

Question 44

• A stretch reflex • Have least delay between sensory input and motor output • For example, stretch reflex (such as patellar reflex) • Completed in 20–40 msec • Receptor is muscle spindle

Answer 44

Monosynaptic Reflexes

Question 45

* Stretch reflexes * Maintain normal upright posture * Stretched muscle responds by contracting * Automatically maintain balance

Answer 45

Postural reflexes also monosypatic reflex

Question 46

* More complicated than monosynaptic reflexes * Interneurons control more than one muscle group * Produce either EPSPs or IPSPs

Answer 46

Polysynaptic Reflexes

Question 47

``` • Prevents skeletal muscles from: • Developing too much tension • Tearing or breaking tendons • Sensory receptors unlike muscle spindles or proprioceptors ```

Answer 47

Tendon Reflex

Question 48

* Move body part away from stimulus (pain or pressure) * For example, flexor reflex * Pulls hand away from hot stove * Strength and extent of response * Depend on intensity and location of stimulus

Answer 48

Withdrawal Reflexes

Question 49

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

Answer 49

Reciprocal Inhibition