Topic 19 -peripheral nervous system

Question 1

cranial nerves all 12 pairs

Answer 1

1 olfactory 
2 optic
3 oculomotor 
4 Trochlear
5 Trigeminal  
6 Abducens 
7 Facial 
8 Vestibulocochlear 
9 Glossopharyngeal 
10 Vagus 
11 Accessory 
12 Hypoglossal

Question 2

which cranial nerves are associated with the forebrain

Answer 2

1 olfactory

2 optic

Question 3

which cranial nerves are associated with the midbrain

Answer 3

3 oculomotor

4 trochlear

Question 4

which cranial nerves are associated with the pons

Answer 4

5 trigeminal
6 abducens
7 facial
8 vestibulocochlear

Question 5

which cranial nerves are associated with medulla oblongata

Answer 5

9 glossopharyngeal
10 vagus
11 accessory
12 hypoglossal

Question 6

2 pairs of cranial nerves are only Sensory

Answer 6

sensory
1 olfactory
2 optic

Question 7

1 pair of cranial nerves is mainly sensory

Answer 7

sensory

8 vestibulocochlear

Question 8

9 pairs of cranial nerves are

Answer 8

mixed nerves

• carry both sensory + motor neurons
• motor neurons ⇒ cell bodies in brainstem nuclei
• sensory neurons ⇒ cell bodies in ganglia of PNS
• e.g. trigeminal (V)
• motor function = chewing
• sensory function = conveys general sensations (touch, pressure, pain, temperature etc) from face to CNS

Question 9

Spinal nerves

Answer 9

• 31 pairs = all mixed nerves
• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

Question 10

spinal nerves exit at

Answer 10

exit via intervertebral foramina (except 1st - between atlas + occipital bone

Question 11

each spinal nerve has two points of attachment to spinal cord:

Answer 11

a) Dorsal Root
- sensory; cell bodies in dorsal root ganglion
b) Ventral Root
- autonomic and somatic motor neurons; cell bodies in ventral or lateral horn

Question 12

• spinal nerve = joining of dorsal + ventral roots

- immediately divides into branches = rami:

Answer 12

a) dorsal ramus
innervates skin + muscles of back
b) ventral ramus
- forms thoracic nerves (T2 - T12) OR further branch + join up forming nerves plexuses (= nerve networks)
c) rami communicantes
- connect ventral ramus to sympathetic trunk
- contain autonomic nerve fibres (neurons)

Question 13

cervical plexus

Answer 13

C1-C5

phrenic (innervates diaphragm)

Question 14

brachial plexus

Answer 14

C5-C8, T1

Axillary, radial,ulnar, median, musculocutaneous

Question 15

Lumbar plexus

Answer 15

L1-L4

femoral

Question 16

Sacral

Answer 16

L4-S4

sciatic => divides into tibial and common fibular

Question 17

Peripheral Nervous system: Sensory (Afferent) Division

consists of

Answer 17

stimulus -> receptor -> CNS
Receptors
First order Neurons

Question 18

Receptors

Answer 18

detect changes in environment 
classified by 
location 
type of stim received 
structure of receptor

Question 19

receptors classified by location

Answer 19

i) exteroceptors
- stimulus in external environment = receptors at body surface e.g. touch, most special senses)
ii) interoceptors
- stimulus in internal environment (in viscera, blood vessels etc)
iii) proprioceptors
- located in joints, skeletal muscles etc
- monitor body position (stretch receptors, muscle spindles) – balance + movement

Question 20

receptors classified based on type of stim received

Answer 20

i) mechanoreceptor- mechanical stimuli (e.g. pressure, touch, hearing)
ii) thermoreceptors- temperature
iii) chemoreceptors- chemical
iv) photoreceptors- light
v) nociceptors - pain`

Question 21

receptors based on structure

Answer 21

i) free nerve endings - terminal dendrites of unipolar sensory neurons e.g. pain, root hair plexus
ii) encapsulated nerve endings - terminal dendrites enclosed in CT
e. g. Meissner’s + Pacinian corpuscles

Question 22

First Order Neurons = sensory neurons

Cell bodies where

Axon terminates where

Answer 22

• unipolar neurons attached to or associated with receptor
• axon located in cranial/spinal nerves to CNS
• cell bodies in:
  a) sensory ganglia of cranial nerves
  b) dorsal root ganglia of spinal cord-

axon terminals in:

a) brain nuclei
b) dorsal horn of spinal cord

Question 23

Peripheral system: Motor (efferent) Division

Answer 23

CNS => effector (E)
2 subdivisions
somatic
autonomic

Question 24

Somatic peripheral nervous system

Answer 24

• effector = skeletal muscle
• consists of lower motor neurons (= motor neurons):
  = single multipolar neuron:
  a) cell body in ventral horn of spinal cord to effector
  b) cell body in motor nuclei of brain stem to effector (e.g. facial motor nucleus for cranial nerve VII)

Question 25

Autonomic division of nervous system

Answer 25

• effector = smooth muscle, cardiac muscle, glands
• 2 successive multipolar neurons from CNS to effector:
  a) preganglionic neuron
• myelinated
• cell body in brain stem or lateral horn of spinal cord
  b) postganglionic neuron
• unmyelinated
• cell body in autonomic ganglion (outside CNS)

Question 26

2 subdivisions of autonomic nervous system

Answer 26

a) Sympathetic (SNS)

b) Parasympathetic (PSNS)

Question 27

Differences between SNS and PSNS for Cell body of preganglionic neuron

Answer 27

SNS: lateral horn T1 => L2
PSNS: Brain stem S2=>S4

Question 28

Differences between SNS and PSNS for Autonomic ganglia

Answer 28

SNS: Trunk (either side of column) OR collateral (ant to vert column or close to large abdominal arteries)

PSNS: terminal (at or in organ/effector wall)

Question 29

Differences between SNS and PSNS for Postganglionic neurons

Answer 29

SNS: long axons
PSNS: Short axons

Adrenal medulla= modified postganglionic neurons of SNS

Question 30

Differences between SNS and PSNS for Functions

Answer 30

SNS: flight or fight
PSNS: Rest and digest

Question 31

Differences between SNS and PSNS for exit CNS (nerves)

Answer 31

SNS: mainly as thoracic nerves
PSNS: mainly 80% via vagus (cranial nerve X)