Lecture 14 - The PNS

Question 1

how many pairs of cranial nerves are there?

Answer 1

12

Question 2

how many pairs of spinal nerves are there?

Answer 2

31

Question 3

what structures are innervated by the somatic nervous system?

Answer 3

skin, muscle, bone, parietal membranes

Question 4

what type of tissue does the somatic motor system innervate?

Answer 4

skeletal muscle, voluntary control (exception - reflex arc)

Question 5

what types of sensation are somatic sensory neurons responsible for feeling?

Answer 5

pain, temperature, touch, proprioception

Question 6

what type of pain is felt by somatic sensory neurons?

Answer 6

direct pain arising from the site of the injury; sharp, focussed and well-localized

Question 7

what type of tissue does the autonomic nervous system innervate?

Answer 7

supplies viscera (glands, smooth muscle, cardiac muscle, visceral membranes)

Question 8

what type of pain is felt by the autonomic sensory neurons?

Answer 8

stretch or lack of oxygen at the organs, vague, ill-defined and ache like, perceived as indirect or referred pain

Question 9

spinal nerves are bundles of:

Answer 9

axons

Question 10

at what point do the spinal nerves exit the vertebral column below the vertebrae and not above?

Answer 10

transition point at C8

Question 11

what are the four main classes of spinal nerves?

Answer 11

• somatic afferents (GSA)
• visceral afferents (GVA)
• somatic efferents (GSE)
• visceral efferents (GVE)

Question 12

detects pain, temperature, touch, and proprioception from the body wall

Answer 12

somatic afferents (GSA)

Question 13

detects pain, distension, and chemical changes in visceral structures

Answer 13

visceral afferents (GVA)

Question 14

motor neurons in the ventral horn projecting to skeletal muscles

Answer 14

somatic efferents (GSE)

Question 15

autonomic fibres (sympathetic or parasympathetic) innervating smooth muscle, cardiac muscle, and glands

Answer 15

visceral efferents (GVE)

Question 16

what are the two primary branches of the spinal nerve?

Answer 16

dorsal primary ramus, ventral primary ramus

Question 17

the dorsal and ventral roots are _____ long, and join up to form the ______

Answer 17

~1cm, spinal nerve

Question 18

the spinal nerve exits the vertebral column through the:

Answer 18

intervertebral foramen

Question 19

a dense irregular connective tissue that surrounds a whole spinal or peripheral nerve and fills the spaces between the nerve fascicles

Answer 19

epineurium

Question 20

a protective sheath that surrounds an individual nerve fascicle

Answer 20

perineurium

Question 21

a protective sheath that acts like a saran wrap around an individual axon and its myelin sheath

Answer 21

endoneurium

Question 22

an area of skin supplied by nerves from a single spinal root (all spinal nerves innervate a band of skin)

Answer 22

dermatomes

Question 23

what are the three somatic nerve plexuses?

Answer 23

• brachial plexus
• lumbar plexus
• lumbosacral plexus

Question 24

in a nerve plexus, all of the nerves ____ with one another

Answer 24

interact

Question 25

which spinal nerves form the brachial plexus?

Answer 25

C5, C6, C7, C8, and T1

Question 26

what are the five main nerves that stem from the brachial plexus?

Answer 26

1) axillary (shoulder) 2) musculocutaneous (biceps) 3) median (forearm flexors, thenar) 4) radial (posterior arm and forearm) 5) ulnar (hand muscles - except thumb)

Question 27

which spinal nerves form the lumbar plexus?

Answer 27

L1, L2, L3, L4

Question 28

what is the main nerve that stems from the lumbar plexus?

Answer 28

the femoral nerve (anterior compartment of thigh)

Question 29

which spinal nerves form the lumbosacral plexus?

Answer 29

L4, L5, S1, S2, S3

Question 30

what are the two main nerves that stem from the lumbosacral plexus?

Answer 30

1) tibial (posterior thigh, toe muscles) 2) common peroneal (lateral leg, 'foot drop')

Question 31

what are the five main steps of the reflex arc?

Answer 31

1) arrival of stimulus and activation of receptor 2) activation of a sensory neuron 3) interneuron sends information to be processes in the CNS 4) interneuron activates the motor neuron 5) response by effector

Question 32

what is the purpose of the reflex arc?

Answer 32

to remove the body from a painful or uncomfortable stimulus

Question 33

the autonomic nervous system is a _____ pathway

Answer 33

two neuron

Question 34

which region of the of the spinal cord/brainstem is part of the sympathetic nervous system?

Answer 34

thoracolumbar --> T1-L2

Question 35

which region of the spinal cord/brainstem is part of the parasympathetic nervous system?

Answer 35

craniosacral --> CN III, CN VII, CN IX, CN X, S2, S3, S4

Question 36

in the somatic motor system, one axons emerges from the ____, and travels to the ____. this is known as the ____

Answer 36

CNS, effector site, 'common final pathway'

Question 37

in the autonomic motor system, the preganglionic fibre travels from the _____, and travels to the _____

Answer 37

CNS, autonomic ganglion

Question 38

in the autonomic motor system, the postganglionic fibre travels from the _____, and travels to the _____

Answer 38

ganglion, effector site

Question 39

- has a short preganglionic fibre - has a long postganglionic fibre - releases norepinephrine/epinephrine into the bloodstream (adrenal medulla) or onto the target tissue these are all characteristics of the:

Answer 39

sympathetic nervous system

Question 40

- has a long preganglionic fibre - has a short postganglionic fibre - releases acetylcholine at the target tissue these are all characteristics of the:

Answer 40

parasympathetic nervous system

Question 41

what effect does the sympathetic nervous system have on the eyes?

Answer 41

dilates pupils

Question 42

what effect does the sympathetic nervous system have on the salivary glands?

Answer 42

thick viscid secretion

Question 43

what effect does the sympathetic nervous system have on the trachea and bronchioles?

Answer 43

dilation

Question 44

what effect does the sympathetic nervous system have on the heart?

Answer 44

increases heart rate and contractility

Question 45

what effect does the sympathetic nervous system have on the ureters and bladder?

Answer 45

relaxes detrusor m., contracts trigone and sphincter (prevents voiding)

Question 46

what effect does the sympathetic nervous system have on the gastrointestinal system?

Answer 46

decreases motility and tone, contracts sphincters

Question 47

what effect does the sympathetic nervous system have on the genetalia?

Answer 47

male - stimulates ejaculation female - relaxes uterus (partuition)

Question 48

what effect does the sympathetic nervous system have on the blood vessels?

Answer 48

skeletal muscle - dilates viscera - constricts

Question 49

list the steps that sympathetic nerves takes to innervate the skin

Answer 49

1) preganglionic sympathetic neuron travels down the ventral root in the white ramus communicantes 2) synapses in sympathetic chain ganglion 3) signal exits the ganglion and travels to the skin down the gray ramus communicantes

Question 50

list the steps that sympathetic nerves takes to innervate the heart and lungs

Answer 50

1) preganglionic sympathetic neuron travels down the ventral root in the white ramus communicantes 2) synapses in sympathetic chain ganglion 3) signal travels up the chain 4) the signal exits the chain and travels to the heart/lungs

Question 51

list the steps that sympathetic nerves takes to innervate the abdominal viscera

Answer 51

1) preganglionic sympathetic neuron travels down the ventral root in the white ramus communicantes 2) signal passes through the sympathetic chain ganglion and travels down the splanchnic nerves 3) synapses at the celiac ganglia 4) signal travels along nerves surrounding the celiac artery

Question 52

cutaneous and visceral sensory (pain) neurons share the same:

Answer 52

ascending tracts to the brain

Question 53

what is referred pain?

Answer 53

pain in the visceral organs is often felt at the skin because the brain can't tell the difference between cutaneous and visceral signals

Question 54

what effect does the parasympathetic nervous system have on the eyes?

Answer 54

pupil constriction and accomodation reflex

Question 55

what effect does the parasympathetic nervous system have on the lacrimal glands?

Answer 55

stimulates tears

Question 56

what effect does the parasympathetic nervous system have on the salivary glands?

Answer 56

copious watery secretion

Question 57

what effect does the parasympathetic nervous system have on the trachea and bronchioles?

Answer 57

constricts them and increases secretion

Question 58

what effect does the parasympathetic nervous system have on the heart?

Answer 58

decreases heart rate and decreases contractility

Question 59

what effect does the parasympathetic nervous system have on the ureters and bladder?

Answer 59

contracts the detrusor m., relaxes trigone and sphincter (voids bladder)

Question 60

what effect does the parasympathetic nervous system have on the gastrointestinal system?

Answer 60

increases motility and tone

Question 61

what effect does the parasympathetic nervous system have on the genetalia?

Answer 61

stimulates erection

Question 62

the autonomic motor system is controlled by the:

Answer 62

hypothalamus