Nerve Lab

Question 1

Location of the spinal chord. Begins and ends where? Ends as _____.

Answer 1

begins at the foramen magnum

ends between L1 and L2 as conus medullaris

Question 2

What is the fibrous extension that anchors the spinal chord to the coccyx

Answer 2

filum terminale

Question 3

what is the collection of nerve roots at the inferior end of the vertebra canal? What 2 nerves do they contain?

Answer 3

cauda equina

lumbar & sacral nerves

Question 4

What are the 2 functins of the spinal chord?

Answer 4

• provides communication to and from the brain

- contains spinal reflex centers

Question 5

What type of neurons are located in the dorsal, ventral, and lateral grey horn?

Answer 5

dorsal = interneurons
ventral = somatic motor neurons
lateral = visceral motor neurons

Question 6

Spinal nerve is formed by the union of these 2.

Answer 6

dorsal & ventral roots

Question 7

The cell bodies of what type of neurons are located in the dorsal root ganglion?

Answer 7

sensory neurons

Question 8

Myelinated axons run through here (3).

Answer 8

dorsal, lateral, ventral white columns (funiculi)

Question 9

Damage of the phrenic nerve causes

Answer 9

respiratory failure

Question 10

What are the 5 nerves in the brachial plexus?

Damage in the brachial plexus causes

Answer 10

• axillary nerve
• musculocutaneous nerve
• radial nerve
• median nerve
• ulnar nerve
• loss of sensation in the arm

Question 11

Which nerve is in the lumbar plexus? (2)
Where does it innervate?
damage in the lumbar plexus causes (2)

Answer 11

• femoral nerve & saphenous
• quadriceps
• cant flex hips or extend knee

Question 12

Which nerve is in the sacral plexus?
What does it innervate? (4)
damage in the sacral plexus causes (3)

Answer 12

• sciatic nerve
• hamstring, adductor Magnus, legs/foot
• no flexion of knee, leg useless, “footdrop”

Question 13

Stretching of this plexus causes a football injury called stinger.

Answer 13

brachial plexus

Question 14

Which nerve is involve in the carpal tunnel syndrome

Answer 14

median nerve

Question 15

Which nerve do we hit in funny bone

Answer 15

ulnar

Question 16

Define reflex.

Answer 16

rapid, predictable, involuntary motor responses to stimuli

Question 17

Define reflex arc.

Answer 17

nerve pathways of a reflex

Question 18

Define muscle spindle.
What does it excite and initiate?

What do the golgi tendon organs inform? What does it excite and initiate?

Answer 18

• inform the nervous system of the length of the muscle
• excited by stretch of the muscle, initiate contraction
• inform the brain the amount of tension in the muscle & tendons
• excite by muscle contraction, initiate relaxation

Question 19

Define monosynaptic vs polysynaptic reflexes.

Answer 19

• mono = one chemical synapse between one sensory and one motor neuron
• poly = more than one chemical synapse involving interneurons

Question 20

What are the 5 components of a reflex arc? simple

Answer 20

1. receptor - site of stimulus
2. sensory neuron - transmits afferent impulses to the CNS
3. integration center - mono or polysynaptic region withini the CNS
4. motor neuron - conducts efferent impulses to an effector organ
5. effector - muscle/gland responds by contracting or secreting

Question 21

Why is reflex testing an important part of every exam? What does a hyperactive reflex indicate? hypoactive?

Answer 21

• test for proper functioning of the nervous system
• hyperactive = damage to the corticospinal tract and loss of brains inhibitory input
• hypoactive = peripheral nerve damage or ventral horn damage

Question 22

What is the difference between an inborn/intrinsic and learned/acquired reflex? What is an example?

Answer 22

• inborn = a rapid, involuntary, predictable motor response to a stimulus
  ex. Splash boiling water on arm, drop pot

-acquired = result from practice or repetition,
Example: driving skills.

Question 23

all stretch reflexes are _____ and _____.

Answer 23

monosynaptic and ipsilateral

Question 24

What are the 3 steps to a stretch reflex? What happens at the same time?

Answer 24

1. stretch activates the muscle spindle (propioceptor)
2. sensory neurons synapse directly with the motor neuron
3. motor neuron causes stretched muscle to contract

-inhibit motor neurons of antagonist

Question 25

What muscles and nerve are responsible for the patellar reflex? Is the patellar reflex monosynaptic or polysynaptic?

Answer 25

- muscle spindles in quadriceps - nerve L2-L4 - prevent antagonist (hamstring) - monosynaptic

Question 26

What 2 reflexes consist of a crossed extensor reflex? What are examples? Is it poly or monosynaptic?

Answer 26

ipsilateral flexor reflex & contralateral extensor reflex - step on glass; purse snatching - polysynaptic

Question 27

What kind of reflex is a plantar reflex? What is the stimulus? The response? What function does it test for? What is babinski's sign? In who is it presented? Why? What does it indicate in adults?

Answer 27

- superficial - Stimulus: stroking lateral aspect of the sole of the foot - Response: downward flexion of the toes - tests function of corticospinal tracts - response: dorsiflexion of hallux and fanning of toes - Present in infants due to incomplete myelination - In adults, indicates corticospinal or motor cortex damage

Question 28

What are the 5 components of a reflex arc complicated?

Answer 28

1. arrival of stimulus & activation of a receptor 2. propogation of AP along sensory neuron. reaches the spinal cord via the dorsal root 3. excitatory neurotransmitters released by the synaptic knob of sensory neuron, which then arrives at the postysynaptic membrane of the interneuron, which creates a EPSP (interneuron may or may not be present) 4. AP propagates down the motor neuron via the ventral root of the spinal nerve 5. release of neurotransmitters by motor neuron causes response from effector

Question 29

What are the 4 ways to classify reflexes?

Answer 29

1. development - innate vs acquired 2. response - somatic-skeletal vs visceral-control (smooth, cardiac muscles & glands) 3. processing site - spinal vs cranial 4. complexity of circuit - mono vs polysynaptic

Question 30

stretch reflex (simple)

Answer 30

increasing muscle length activates sensory neuron that triggers the motor response of contraction of muscle

Question 31

patellar reflex (simple) - what does it stretch after stimulation of what?

Answer 31

type of stretch reflex that contracts the quadriceps after stimulating the muscle spindles of quadricpes

Question 32

polysynaptic reflexes (simple)

Answer 32

involve several muscle groups and excitatory/inhibitory post synaptic potentials

Question 33

What does a tendon reflex prevent? How does that happen?

Answer 33

- prevents tearing/breaking of tendons | - increase in tension = increase inhibitory effect on muscles so doesn't break

Question 34

withdrawal reflex

Answer 34

move affected parts away from the stimulus (pain, pressure, touch)

Question 35

flexor reflex

Answer 35

stimulation of flexor muscles and inhibition of extensor muscles

Question 36

crossed extensors reflex What tye of reflex arc is it? (2) What happens? What does it support? Is it mono or polysynaptic?

Answer 36

- ipsilateral and contralateral reflex arc - stimulation of one leg causes flexor stimulation and extensor inhibition. the opposite occurs in the other leg to support body weight - polysynaptic

Question 37

What are the 5 characteristics of crossed extensor reflexes?

Answer 37

1. involve interneurons 2. intersegmental in distribution (activate many muscles) 3. involve reciprocal inhibition (coordinates muscular contraction) 4. have reverberating circuits (prolong reflex motor response) 5. several reflexes cooperate to produce a coordinated/controlled response

Question 38

What is a muscle spindle? What is it excited and what does it initiate? Where is it found? Is it sensory or motor?

Answer 38

- -inform the nervous system of the length of the muscle - excited by stretch of the muscle, initiate contraction - found in skeletal muscle - sensory

Question 39

Pupillary reflex What is response? Why do you get the consensual response? What 2 nerves mediate it and what do they do?

Answer 39

- response: constriction of iris due to light - regulate the amount of light that enters the eye - optic (carry light impulse) & oculomotor nerve (constrict)

Question 40

Achilles reflex what action, what muscles, what nerves? mono or polysynaptic?

Answer 40

- foot jerks toward plantar surface - gastrocnemius muscle - S1 and S2 of the tibial nerve - monosynaptic