Exam 2: Lecture 14 Cranial nerves

Question 1

cranial nerves

Answer 1

exit or enter the central nervous system through holes in the skull, NOT through spinal foramina
- 12 pairs

Question 1

what do the cranial nerves provide? (3)

Answer 1

sensory, motor and autonomic innervation to the head

Question 2

cranial foramina

Answer 2

the holes in the skull cranial nerves go through

Question 3

CN 1

Answer 3

olfactory

Question 4

CN 2

Answer 4

optic

Question 5

CN 3

Answer 5

oculomotor

Question 6

CN 4

Answer 6

trochlear

Question 7

CN 5

Answer 7

trigeminal

Question 8

CN 6

Answer 8

abducens

Question 9

CN 7

Answer 9

facial

Question 10

CN 8

Answer 10

vestibulocochlear (auditory)

Question 11

CN 9

Answer 11

glossopharyngeal

Question 12

CN 10

Answer 12

vagus

Question 13

CN 11

Answer 13

spinal accessory

Question 14

CN 12

Answer 14

hypoglossal

Question 15

sensory innervation examples

Answer 15

somatic (pain, touch, vibration) and special (olfaction, vision, taste, hearing)

Question 16

motor innervation examples

Answer 16

skeletal muscles

Question 17

autonomic innervation examples

Answer 17

pupil dilation, tears, nose running, sweat, saliva, heart rate, blood pressure, respiration rate. Etc.

Question 18

olfactory nerve

Answer 18

(1) special sense of smell ⇒ nerves are in the nasal epithelium
- enter skull through cribriform plate
- The neurons in the olfactory bulbs send axons through the olfactory tract to the cerebral cortex ⇒ NOT THALAMUS

Question 19

optic nerve

Answer 19

(2) the sense of vision ⇒ cells in the retina of the eye send their axons through the optic nerve
- Many of the axons cross (decussate) in the optic chiasm
- They continue to the optic tract to the thalamus

Question 20

oculomotor nerve

Answer 20

(3) 1. innervates skeletal muscle (4/6 extra ocular muscles)
2. Parasympathetic function (autonomic) to constrict pupil and focus lens ⇒ muscles to open eyelid
- innervate ciliary ganglion in the back of the eye socket for focus and pupil dilation

Question 21

ciliary body

Answer 21

contracts the lens so it becomes larger

Question 22

what happens when the posterior cerebral artery enlarges?

Answer 22

can cause abnormal function of CN3
- Ipsilateral eye doesn’t move properly
- Pupil will dilate
- Eyelid droops

Question 23

trochlear nerve

Answer 23

(4) innervates the superior oblique muscle to move the eye down and out

Question 24

what cranial nerve is the only one to exit from the dorsal surface of the brain?

Answer 24

trochlear nerve (CN 4)

Question 25

trigeminal nerve

Answer 25

innervates skeletal muscle of mastication and causes cutaneous sensation from the head and face
- Temporalis (superior) and masseter (inferior) ⇒ muscles that allow you to chew your food

Question 26

what is the only cranial nerve to emerge form the middle of the pons?

Answer 26

trigeminal nerve (CN 5)

Question 27

3 branches of cutaneous (trigeminal n) sensation

Answer 27

1. Ophthalmic (V1)⇒ forehead and eye
2. Maxillary (V2)⇒ cheek and nose
3. Mandibular (V3) ⇒ lower jaw

Question 28

abducens nerve

Answer 28

(6) innervates one extra ocular muscle called the lateral rectus muscle
- moves the eye laterally

Question 29

facial nerve

Answer 29

(7) innervates skeletal muscles for facial expression ⇒ smiling, frowning, scowling, etc.
and taste receptors in the anterior ⅔ of the tongue
- does a lot of things such as innervates parasympathetic ganglia that innervate lacrimal glands, nasal mucosal glands, and salivary lands
- tears, snot, and saliva

Question 30

vestibularcochlear nerve

Answer 30

(8) special sensory information like hearing and balance
- Both cochlea (sound) and vestibular (balance/position/movement) apparatus have hair cells

Question 31

glossopharyngeal nerve

Answer 31

(9) innervates stylopharyngeus muscle responsible for elevating the pharynx during swallowing and receives sensory information and taste from posterior ⅓ of tongue
- pain, touch, etc.
- innervates autonomic ganglion responsible for the stimulation of the parotid gland (salivation)

Question 32

vagus nerve

Answer 32

(10) innervates skeletal muscles for swallowing and autonomic input to the heart and gut
- Sense blood oxygenation and CO2
- Innervates skeletal muscles of the throat and larynx for swallowing
- General sensation ⇒ behind ear and larynx
- Special sensation of taste ⇒ back of throat

Question 33

spinal accessory nerve

Answer 33

(11) Innervates 2 skeletal muscles that allow turning your head and shrugging your shoulders
- Trapezius muscle and sternocleidomastoid muscle
- Axons enter the skull through the foramen magnum and then exit the skull through the jugular foramen

Question 34

hypoglossal nerve

Answer 34

(12) innervates the muscles of the tongue for movement

Question 35

which nerves carry special senses only? (3)

Answer 35

Olfactory (smell)
Optic (vision)
Vestibulocochlear (hearing)

Question 36

which nerves innervate skeletal muscle and do nothing else? (5)

Answer 36

Oculomotor (eye)
Troclear (eye)
Abducens (eye)
Spinal accessory (neck/shoulder)
Hypoglossal (tongue)

Question 37

which nerve innervate muscle and carries general sensation of touch, vibrations, etc.? (1)

Answer 37

Trigeminal
(jaw, muscles, sensation for face, head, mouth)

Question 38

which nerves have mixed function? (3)

Answer 38

Facial
Glossopharyngeal
Vagus