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Cranial Nerves
The 12 cranial nerves
43
Anatomy
Undergraduate 3
01/21/2014

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Cards

Term
Name the 12 cranial nerves, and whether they are sensory, motor, or both?
Definition
1. Olfactory - S
2. Optic - S
3. Oculomotor - M
4. Trochlear - M
5. Trigeminal - B
6. Abducens - M
7. Facial - B
8. Vestibulocochlear (acoustic) - S
9. Glossopharyngeal - B
10. Vagus - B
11. Spinal accessory - M
12. Hypoglossal - M
Term
Which what sensory CN's do not synapse at the brainstem?
Definition
CN I and II
Term
What is the function of CN I?
Definition
Smell
Term
Describe the pathway of this nerve?
Definition
A small group of neurons originates in the olfactory mucosa, and penetrate the holes of the cribiform plate to enter the olfactory bulb. These small nerves synapse in the bulb, and the secondary nerves form the olfactory nerves
Term
Where does CN I go back to?
Definition
The Rhinencephalon (olfactory cortex)
Term
What is the function of CN II?
Definition
Sight
Term
Describe the pathway of this nerve?
Definition
Nerve fibres leave the retina, and form the optic nerves when they leave the eye. These nerves coalesce in the optic chiasm, and from here the left and right optic tracts emerge
Term
What then happens to the optic tracts?
Definition
They pass posteriorly and synapse in the lateral geniculate bodies of the thalamus
Term
(T/F) The left optic tract carries visual information from the right visual field, and vice versa.
Definition
True
Term
What is the function of CN III, IV and VI?
Definition
Eye movement
Term
Where do each of these nerves originate?
Definition
III: junction of midbrain and pons
IV: junction of midbrain and pons
VI: junction of medulla and pons
Term
What 4 muscles does CN III innervate?
Definition
- Superior, inferior and medial rectus
- Levatator palpebrae superioris
Term
What muscle does CN IV innervate?
Definition
Superior oblique
Term
What muscle does CN VI innervate?
Definition
Lateral rectus
Term
What movement is the superior rectus responsible for? Inferior? Lateral? Medial?
Definition
- Rotation upwards
- Rotation downwards
- Rotation towards the nose
- Rotation laterally
Term
(T/F) All 3 of these nerves share a common exit point of the skull
Definition
True
Term
What is this point?
Definition
The superior orbital fissure
Term
What is the function of CN V?
Definition
Jaw movement and facial sensation
Term
Name the 4 components of CN V
Definition
1. Opthalmic 2. Maxillary 3. Mandibular 4. Motor
Term
Where does the opthalamic exit? What is its function?
Definition
- Superior orbital fissure - Sensation of the forehead
Term
Where does the maxillary exit? What is its function?
Definition
- foramen rotundum
- Sensation of the cheek
Term
Where does the mandibular exit? What is its function?
Definition
- Foramen ovale - Sensation for the jaw, innervation of the muscles of mastication
Term
Which component of the trigeminal nerve is the only component to exit the pons? What is the function of this component? What nerve carries innervation from this component to the target tissue?
Definition
Motor component; innervates muscles of mastication; mandibular nerve
Term
What is the function of CN VII?
Definition
- Motor: Innervates the muscles of facial expression - Sensory: anterior 2/3 of tongue - PNS supply to salivary glands
Term
How does it exit the skull?
Definition
Via the stylomastoid foramen
Term
Describe its pathway
Definition
Exits the brainstem lateral to CN VI and passes through the internal acoustic meatus. It then travels to the middle ear and leaves via the stylomastoid foramen and fans out.
Term
How many branches does CN VII fan out to after leaving the skull?
Definition
5
Term
What is the function of CN VIII?
Definition
- Hearing
- Sense of balance
Term
Where does it exit the skull?
Definition
It doesn't
Term
Describe its pathway?
Definition
Leaves brainstem lateral to CN VII and enters the internal acoustic meatus
Term
What is the function of CN IX?
Definition
- PNS innervation of salivary glands - Motor: innervation to stylopharngeus muscle - Sensory: posterior 1/3 of tongue and pharynx
Term
Where does it leave the skull?
Definition
Jugular foramen
Term
Describe its pathway
Definition
Leaves the medulla below CN VIII, then leaves the jugular foramen
Term
What is the function of CN X?
Definition
- PNS innervation to thorax and abdomen
- Sensory and motor innervation to the larynx
Term
Where does it exit the skull?
Definition
Jugular foramen
Term
Describe its pathway?
Definition
Exits medulla just below CN IX and joins it, leaving through the jugular foramen
Term
(T/F) CN X is a very small nerve,
Definition
False, it is large
Term
What is the function of CN XI?
Definition
Motor to the trapezius and sternoclenomastoid
Term
(T/F) All rootlets of this nerve originate in the medulla
Definition
False, some have their origins in the upper cervical levels
Term
Describe their pathway?
Definition
Cervical roots join and travel towards the foramen magnum. Medullary roots come from just below CN X and the fibres together make up CN XI. The combined fibres leave via the jugular foramen
Term
What is the function of CN XII?
Definition
Supplies intrinsic and extrinsic muscles of the tongue
Term
Where does it exit the skull?
Definition
Hypoglossal canal
Term
Describe its pathway
Definition
The nerve arises from rootlets that exit between the pyramid and olive of the medulla. The rootlets fuse and leave the skull via the hypoglossal canal
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