Intro to Nervous System

Question 1

What are the 2 branches of the nervous system?

Answer 1

Central (Brain & Spinal cord)

Peripheral (Cranial & Spinal nerves)

Question 2

What does the brain give rise to?

Answer 2

Cranial nerves

Question 3

Describe the spinal cord

Answer 3

Conducts impulses to and from the brain

Divided in to segments that give rise to spinal nerves

Question 4

What is the basic functional unit of the nervous system?

Answer 4

The neuron

Question 5

Which neuron shape is responsible for most sensory neurons?

Answer 5

Pseudounipolar

Question 6

Define nerve

Answer 6

A collection of cell processes and axons located in the peripheral nervous system

Question 7

What are the supporting cells to a nerve?

Answer 7

PNS - Schwann cells

Connective tissue - Endoneurium, perineurium, epineurium

Question 8

Define a tract

Answer 8

A collection of neuronal cell processes that travel within the central nervous system

Question 9

Define a ganglion

Answer 9

A collection of neuron cell bodies located outside the central nervous system

Question 10

Define a nucleus

Answer 10

A collection of neuron cell bodies located within the central nervous system

Question 11

What is the alternate name for the lateral horn?

Answer 11

Intermediogrey column

Question 12

Where are tracts located in the central nervous system?

Answer 12

White matter

Question 13

What is the main purpose of primary afferent neurons?

Answer 13

Conduct sensory impulses from the peripheral to the central nervous system

Question 14

What is the main function of the final efferent neurons?

Answer 14

Conduct motor impulses from central nervous system to effector organ

Question 15

What is an alternate name for final efferent neurons?

Answer 15

Lower motor neurons

Question 16

Why does the monosynaptic patellar reflex occur?

Answer 16

Hammer taps space, stretching the muscle spindle.

Primary afferent neuron sends signal to brain that the muscle spindle is stretched, brain send signal via lower motor neuron (final efferent) to contract muscle

Question 17

What is an interneuron

Answer 17

A short neuron located between afferent and efferent neurons within the CNS

Excitatory or inhibitory

Question 18

What is the main function of the interneuron?

Answer 18

During a reflex movement, afferent nerves will signal both excitatory and inhibitory neurons

Inhibitory neurons will send efferent signals to inhibit extensor muscle nerves and excitatory neurons will send efferent signals to activate flexor muscle nerves

Question 19

What are projection neurons?

Answer 19

Found only in the central nervous system

Similar to interneurons with longer axons

Question 20

What is an ascending tract of a projection neuron?

Answer 20

Cell body is in the spinal cord, and upper motor neuron projects cranially to terminate in the brain

Question 21

What is a descending tract of an projection nueron?

Answer 21

Pathway begins in a nucleus or cortex of the brain and the axon extends to the brainstem or spinal cord terminating on a lower motor neuron (projection neuron in an upper motor neuron)

Question 22

Which projection neurons are relayed first and why?

Answer 22

Ascending neurons send signals to the brain, descending neurons come next to send the efferent signal to the muscles

Interneurons relay the signal for the withdrawal reflex on one side of the side (activate flexors) and to the contralateral side to activate the extensors of the opposing limb

Question 23

How to classify peripheral motor neurons

Answer 23

Afferent (towards CNS)
Efferent (Away from CNS)

Somatic (main body mass)
Visceral (organs/blood vessels)

Question 24

Define General Somatic Efferent (GSE)

Answer 24

Multipolar neurons that supply most of the skeletal muscles

A single neuron extends from the CNS to all muscle fibers involved

Question 25

Define General Visceral Efferent (GVE)

Answer 25

Multipolar neurons that supply smooth muscle, cardiac muscle, and glands Form the autonomic nervous system 2-neuron chain between the central nervous system and the effector organ

Question 26

Define General Visceral Afferent (GSA)

Answer 26

Pseudounipolar neurons that carry sensory information from the somatic body system to the CNS

Question 27

Where are the cell bodies of GSA neurons located?

Answer 27

Sensory ganglia

Question 28

Define Special somatic Afferent (SSA) and Special Visceral Afferent (SVA) neurons

Answer 28

SSA: bipolar neurons that carry visual and auditory information SVA: Bipolar and pseudounipolar neurons that carry taste and smell sensations

Question 29

What horn do GVE nerves originate from? GVA? GSA? GVA?

Answer 29

GVA and GSA originate from the dorsal horn GVE nerves originate from the lateral horn GSE nerves originate from the ventral horn

Question 30

Describe the anatomy of a spinal nerve

Answer 30

Dorsal and ventral roots originate from grey matter horns and combine at the dorsal root ganglion to form the spinal nerve which then divides in to the dorsal branch, ventral branch and communicating branch

Question 31

Where do spinal nerves exit the central nervous system?

Answer 31

Intervertebral foramen

Question 32

What types of neurons are present in the dorsal root ganglion?

Answer 32

Sensory/afferent ganglion

Question 33

Where do the dorsal branches of the spinal nerve innervate?

Answer 33

Epaxial muscles, dorsal 1/3 of cutaneous innervation

Question 34

Where do the ventral branches of the spinal nerve innervate?

Answer 34

Hypaxial muscles, limbs & ventral 2/3 of cutaneous innervation

Question 35

How are spinal nerves organized?

Answer 35

C1 comes from lateral vertebral foramen of atlas Cervical spinal nerves come out of the IV foramina cranial to their vertebrae (Cervical 2 comes out cranial to C2) Thoracic & lumbar spinal nerves exit the CNS caudal to their vertebrae Sacral nerves exit pelvic and dorsal foramina

Question 36

Why do thoracic and lumbar nerves exit caudal to their vertebrae?

Answer 36

Cervical nerve 8 exits caudal to C7 & cranial to T1