Module 3: Peripheral Nervous System

Question 1

what is the PNS?

Answer 1

everything outside of the CNS (brain and spinal cord)

Question 2

how many pairs of spinal nerves are there?

Answer 2

31 pairs

Question 3

how many cranial nerves are there?

Answer 3

12 pairs

Question 4

what is the composition of the PNS?

Answer 4

1. 31 pairs of spinal nerves
2. ganglia
3. enteric plexuses (GIT)
4. other nerve plexuses
5. sensory receptors

Question 5

what do afferent nerves do?

Answer 5

carry information from sensory receptors to the CNS

Question 6

what are afferent nerves?

Answer 6

somatic: skin, muscle, joint, reflexes and visceral organs (feeling full)

Question 7

what do efferent nerves do?

Answer 7

carry information AWAY from CNS to effector organs

Question 8

what are efferent nerves?

Answer 8

1. somatic, innervate skeletal muscle
2. autonomic, innervates smooth muscle, caridac muscle and glands (parasympathetic and sympathetic)

Question 9

what is the sympathetic nervous system?

Answer 9

fight or flight - increases metabolic rate

Question 10

what are the 5 features of the sympathetic nervous system?

Answer 10

1. sight of origin: thoracolumnar (thoracic start, lumbar finish) shorter than parasympathetic
2. preganglia shorter than parasympathetic
3. have pre and post ganglions
4. postganglia larger than parasympathetic
5. ganglions are close to spinal cord

Question 11

what is the parasympathetic nervous system?

Answer 11

rest and digest - decreases metabolic rate

Question 12

what are the 4 features of the parasympathetic nervous system?

Answer 12

1. sight of origin: cranialsacral (cranium start, sacral finish) - longer than sympathetic
2. postganglia is shorter than sympathetic
3. preganglia is longer then sympathetic
4. ganglions are close to visceral organs

Question 13

what are the 2 types of nerves in the PNS?

Answer 13

1. spinal: arise from the spinal cord
2. cranial: arise from the brain

Question 14

how are the nerves of the PNS classified?

Answer 14

based on impulse direction
1. sensory (dorsal, towards CNS)
2. motor (ventral, away CNS)
3. mixed (both directions)

Question 15

what are the 3 connective tissues protecting the nerves?

Answer 15

1. epineurium
2. perineurium
   3.endoneurium

Question 16

where is the epineruim in the nerve?

Answer 16

outermost connective tissue layer around nerve, epi means upon

Question 17

where is the perinerium in the nerve?

Answer 17

middle connective tissue layer around nerves, peri means around

Question 18

where is the endoneurium in the nerves?

Answer 18

innermost connective tissue layer around nerves, endo means within

Question 19

why do nerves have blood vessels?

Answer 19

nerves need a lot of energy to function

Question 20

how are the 31 spinal nerves distributed?

Answer 20

8 cervical nerves
12 thoraccic nerves
5 lumbar nerves
5 sacral nerves
1 coccygeal nerves

Question 21

how many pairs of cranial nerves are there?

Answer 21

12 pairs

Question 22

what does the vagus nerve do?

Answer 22

longest nerve of the body and works for the organs

Question 23

what is a ramus?

Answer 23

a branch off of a nerve

Question 24

what is the function of the dorsal ramus?

Answer 24

1. mixed spinal nerve
2. sensory and motor innervation to skin and back muscles
3. smaller than ventral ramus

Question 25

what is the function of the ventral ramus?

Answer 25

1. mixed spinal nerves 2. sensory and motor innervation to the rest of the trunk and limbs 3. larger than dorsal ramus

Question 26

what is a nerve plexus?

Answer 26

multiple spinal nerves interacting together to perform a function

Question 27

why is there several nerves working together to form a plexus?

Answer 27

if 1 nerve is broken or damaged complete loss of function doesn't occur

Question 28

what are the 4 main plexuses?

Answer 28

1. cervical: under sternocleidomastoid (sternum-skull) muscle: innervates skin 2. brachial: neck, shoulder: innervates upper limbs 3. lumbar:innervates psoas muscle (attached to lumber spine-femur): innervates ab wall, anterior and medial thigh 4. sacral: posterior lumbar plexus: innervates lower limbs, buttox and pelvis

Question 29

what is the composition of the brachial plexus?

Answer 29

5 roots 3 trunks 3 cords 5 peripheral nerves

Question 30

what are the 5 peripheral nerves in the arm?

Answer 30

1. musculocutaneous nerve 2. axillary nerve 3. radial nerve 4. median nerve 5. ulnar nerve

Question 31

what happens if you damage the brachial plexus?

Answer 31

1. pins and needles 2. funny bone tingles 3. carpal tunnel 5. weakened grip 6. paralysis 7. babies born can have damage called plexus birth palsy 3-6 month recovery, may need surgery to stitch back together

Question 32

where does cranial nerve 1 attach to?

Answer 32

the cerebrum - olfactory

Question 33

where does the cranial nerve 2 attache to?

Answer 33

the diencephalon - optic

Question 34

where do the cranial nerves 3-12 attach to?

Answer 34

the brain stem, so everything else