1.5- Reflexes and Cranial Nerves

Question 1

What happens when a spinal nerve is cut?

Answer 1

both motor and sensory fibers are destroyed

Question 2

What type of cell bodies are found in the dorsal root ganglion?

Answer 2

sensory

Question 3

What type of cell bodies is in the ventral horn of the SC?

Answer 3

Motor

Question 4

What type of gated channel starts a sensory impulse?

Answer 4

modality

Question 5

What starts a motor impulse?

Answer 5

an upper motor neuron

Question 6

A modality gated receptor starts a sensory impulse, which is then carried along the neuron via _________.

Answer 6

voltage gated channels

Question 7

A motor impulse is started by an upper motor neuron via a ___________ through a __________ and continues via _________.

Answer 7

synapse in the brain through a ligand gated channel and continues via voltage gated channel

Question 8

After an upper motor neuron synapses it continues via the _______ until it reaches the ________ and causes a ________.

Answer 8

lower motor neuron (alpha motor neuron) until it reaches the motor end plate and causes a contraction

Question 9

What is a reflex?

Answer 9

an involuntary response to a stimuli

Question 10

What type of reflex is a multisynaptic reflex?

Answer 10

a withdrawal reflex

Question 11

A withdrawal reflex is a _____________.

Answer 11

multisynaptic reflex

Question 12

What type of reflex is a deep tendon (stretch) reflex?

Answer 12

monosynaptic reflex

Question 13

What type of reflex is a monosynaptic reflex?

Answer 13

a deep tendon (stretch) reflex

Question 14

What type of reflex occurs at the SC level- cortex not directly involved?

Answer 14

multisynaptic reflex (withdrawal reflex)

Question 15

Explain a multisynaptic reflex from stimulation until it enters the SC.

Answer 15

sensory receptor is stimulated -> impulse travels along the peripheral process of the afferent nerve and into the dorsal root ganglion -> the central process of the afferent nerve continues into the spinal cord

Question 16

In addition to a multisynaptic reflex going up the cord, the afferent neuron will _________.

Answer 16

synapse on an interneuron in the ventral horn -> the interneuron synapses onto an alpha motor neuron resulting in muscle activation to move a body part

Question 17

Due to the multisynaptic interneuron synapsing in other areas of the SC, a LE reflex will also have influence over ______________.

Answer 17

the opposite extremity

Question 18

• occurs with 1 single synapse (no interneurons)

- faster because fewer synapses

Answer 18

Monosynaptic reflex

Question 19

When a muscle is quickly stretched it fires a _______.

Answer 19

modality gated sensory nerve

Question 20

Monosynaptic reflex~

impulse travels ________ and synapses __________ -> stimulates a _________

Answer 20

impulse travels back to the spinal cord and synapses directly onto the motor neuron -> stimulates muscle contraction

Question 21

If the CNS/brain influence is removed (like with spinal cord injury) a ___________ occurs

Answer 21

hyperactive reflex

- brain through descending control has an inhibitory effect

Question 22

With a hyperactive reflex, brain through descending control has ____________.

Answer 22

an inhibitory effect

Question 23

How many pairs of cranial nerves?

Answer 23

12 pairs

- some sensory, some motor, some both

Question 24

Name the 12 cranial nerves in order.

Answer 24

Oh Oh Oh To Touch And Feel Very Good Vaginas And Hooters

• olfactory
• optic
• oculomotor
• trachlear
• trigeminal
• abducens
• facial
• vestibulocochlear
• glossopharyngeal
• vargus
• accessory
• hypoglossal

Question 25

I. Olfactory
a.
b.
c.

Answer 25

a. sensory- sense of smell
b. only cranial nerve that goes directly into the cortex via the olfactory bulb
c. has large input into the brain (helps establish memory)

Question 26

II. Optic
a.
b.
c.

Answer 26

a. sensory- visual input
b. very large & heavily myelinated- very fast
c. due to large amounts of myelin, it is susceptible to demyelinating diseases (MS)

Question 27

III.  Oculomotor
a.
b.
c.
d.

Answer 27

a. motor
b. controls 4 different eye muscles controlling eye movements up, down, and medial
c. controls eyelids opening
d. autonomic component- pupillary constriction, size of lens to focus eye

Question 28

IV. Trochlear
a.
b.

Answer 28

a. motor

b. controls 1 eye muscle- turns eye down and in

Question 29

V. Trigeminal
a.
b.
c.

Answer 29

a. both motor and sensory
b. sensory- sensation for areas of the face
c. motor- muscles of mastication (chewing)

Question 30

VI. Abducens
a.
b.
c.

Answer 30

a. motor
b. turns eye lateral (Lateral Rectus)
c. primary control for coordination of eye movement

Question 31

VII.  Facial
a.
b.
c.
d.
e.

Answer 31

a. both motor and sensory
b. sensory- taste (anterior 2/3 of tongue)
c. motor- muscles of facial expressions
d. autonomic- causes salivation & tearing of eyes
e. Corneal blink reflex- touch cornea & eyelid shuts

Question 32

VIII. Vestibulocochlear

a.

Answer 32

a. sensory- hearing and balance (vestibular)

Question 33

IX. Glossopharyngeal
a.
b.
c.

Answer 33

a. both sensory and motor
b. sensory- taster posterior 1/3 tongue & sensation back of throat
c. motor- helps with swallowing

Question 34

X.  Vagus
a.
b.
c.
d.

Answer 34

a. both sensory and motor
b. sensory- external ear sensation
c. motor- gag reflex (with IX- glossopharyngeal)
d. Autonomic- heart, lungs, viscera

Question 35

XI. Accessory
a.
b.
c.

Answer 35

a. motor
b. arises in the SC, ascends up the cranium & then exits the cranium (not truly a cranial nerve)
c. trapezius & SCM (shrug should, turn head to opposite side; loss causes winging of the scapula)

Question 36

XII. Hypoglossal

a.

Answer 36

a. motor- muscles of the tongue

Question 37

What cranial nerves are motor, sensory, or both?

Answer 37

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