Cranial Nerves 1-6

Question 1

What kind of fiber is the olfactory nerve?

Answer 1

Special visceral afferent (SVA). Sensory

Question 2

Where does the olfactory nerve start?

Answer 2

The olfactory nerve originates in the olfactory bulb and passes through the cribriform plate of the ethmoid bone to enter the olfactory region of the nasal cavity.

Question 3

What is anosmia?

Answer 3

Anosmia is the loss of smell usually caused by fracture of the ethmoid bone or foster-Kennedy syndrome. - This may also cause a runny nose from cerebrospinal fluid leakage.

Question 4

What is foster-Kennedy syndrome?

Answer 4

Foster-Kennedy syndrome is associated with tumors of the frontal lobe.

Question 5

What other than damage to the ethmoid bone or foster-Kennedy-syndrome can cause anosmia?

Answer 5

Most of the time, anosmia and hyposmia are temporary and are caused by inflammation in the nasal cavity which prevents chemicals from reaching the olfactory epithelium

Question 6

What kind of fiber is the optic nerve?

Answer 6

The optic nerve is SSA (sensory) and SVA (parasympathetic)

Question 7

What is the function of the SVA - parasympathetic fibers of the optic nerve?

Answer 7

The optic nerve is, in addition to our visual nerve, also the afferent limb of the pupillary light reflex. It is sensory and carries information to the brain about whether to constrict or dilate the pupil.

Question 8

What is the optic chiasm?

Answer 8

The optic chiasm is the place of crossing of nasal fibers.

Question 9

What are the nasal fibers of the optic nerve and their function?

Answer 9

The nasal fibers of the optic nerve cross contralaterally in the optic chiasm and provide the temporal vision.

Question 10

What are the temporal fibers of the optic nerve and what is their function?

Answer 10

The temporal fibers are ipsilateral and provides nasal vision

Question 11

Where do the optic fibers terminate?

Answer 11

The optic fibers travel from the retina to the visual cortex in the occipital lobe

Question 12

What is the pathway of the oculomotor nerve?

Answer 12

The oculomotor nerve originates in the midbrain, passes along the lateral wall of the cavernous sinus, passes through the superior orbital fissure and goes inside the tendinous ring before it supplies the muscles and the ciliary ganglion.

Question 13

What two fibers does the oculomotor nerve consist of?

Answer 13

The oculomotor nerve consists of GSE (motor) fibers and GVE (parasympathetic fibers)

Question 14

What muscles does the superior branch of the oculomotor nerve supply?

Answer 14

The superior branch of the oculomotor nerve supplies the:

• Levator palpebrae superioris.
• The superior rectus.

Question 15

What muscles does the inferior branch of the oculomotor nerve supply?

Answer 15

The inferior branch of the oculomotor nerve supplies the:

• Inferior rectus
• Medial rectus
• Inferior oblique

Question 16

What do the parasympathetic fibers of the oculomotor nerve supply?

Answer 16

The parasympathetic fibers of the oculomotor nerve are responsible for the efferent limb of the pupillary light reflex and supplies:

• The ciliary ganglion
• The pupillary muscles
• The ciliary muscles

Question 17

What are the nuclei in the midbrain where the oculomotor nerve originates called?

Answer 17

The motor fibers originate from the oculomotor nucleus.

The parasympathetic fibers originate from the Edinger-Westphal nucleus.

Question 18

What is the pathway of the trochlear nerve?

Answer 18

The trochlear nerve originates in the midbrain, passes through the cavernous sinus, through the superior orbital fissure, outside the tendinous ring and terminates in the superior oblique muscle.

Question 19

What does the trochlear nerve control?

Answer 19

The trochlear nerve controls the superior oblique muscle which controls the downward movement of the eyeball. Keeps the eye from rolling up into orbit.

Question 20

Where does the trigeminal nerve originate?

Answer 20

The trigeminal nerve originates in the pons.

Question 21

Where does the three branches of the trigeminal nerve exit the skull?

Answer 21

• The ophthalmic nerve V1 exits through the superior orbital fissure.
• The maxillary V2 exits through the foramen rotundum.
• The mandibular exits through the foramen ovale.

Question 22

What fibers does the V1 consist of?

Answer 22

The V1 consists of GSA fibers (sensory).

Question 23

What structures does the ophthalmic division innervate with sensory fibers?

Answer 23

V1 has sensory innervation of the:

• Eyeball
• Tip of nose
• Skin of eyes above the eyeball.

Question 24

Which branch of the ophthalmic nerve mediates the afferent limb of the corneal reflex (blink reflex)?

Answer 24

The nasociliary branch.

Question 25

Describe the pathway and branches of the ophthalmic nerve.

Answer 25

Question 26

What fibers does the maxillary nerve consist of?

Answer 26

The maxillary nerve is a sensory nerve consisting of GSA fibers.

Question 27

What is the pathway of the maxillary nerve?

Answer 27

The maxillary nerve starts in the pons, goes through the lateral wall of the cavernous sinus, exits the skull through the foramen rotundum and enters the pterygopalatine fossa.

Question 28

What structures does the maxillary nerve provide sensory innervation to?

Answer 28

The maxillary nerve provides sensory innervation to the:

• Skin of face between the eyes and the upper lip.
• Palate
• Paranasal sinuses.
• Maxillary teeth.

Question 29

What reflex does the maxillary nerve supply?

Answer 29

The maxillary nerve contains the afferent limb of the sneeze reflex.

Question 30

Describe the pathways and branches of the maxillary nerve

Answer 30

Question 31

What fibers does the mandibular nerve consist of?

Answer 31

The mandibular nerve is both GSE and GSA.

Question 32

What is the pathway of the mandibular nerve?

Answer 32

The mandibular nerve starts in the pons, passes outside of the cavernous sinus, through the foramen ovale and enters the infratemporal fossa.

Question 33

What muscles does the motor nerve of the mandibular nerve innervate?

Answer 33

The motor nerves of the mandibular nerve innervates the:

• Anterior belly of digastric (elevate hyoid bone - swallowing)
• Mylohyoid muscle (elevate hyoid bone)
• Tensor veli palatini (tenses soft palate - helps prevent food to enter the nasopharynx during swallowing)
• Tensor tympani (dampens noise produced by shewing)
• Muscles of mastication (masseter, medial pterygoid, temporalis - moves mandible up | lateral pterygoid - lower the mandible)

Question 34

What does the sensory fibers of the mandibular nerve innervate?

Answer 34

The sensory fibers of the mandibular nerve innervate the:

• The facial skin of the lower third of the face.
• The inferior row of teeth and gingiva.
• The anterior two thirds of the tongue.

Question 35

Describe the pathways and branches of the mandibular nerve

Answer 35

Question 36

Which reflex does the mandibular nerve innervate?

Answer 36

The mandibular nerve innervates the afferent and efferent limb of the jaw jerk reflex.

Question 37

What nerves innervates the anterior, middle and posterior part of the dura mater?

Answer 37

Anterior - V1

Middle - V2 and V3

Posterior - CN10 and C1

Question 38

Where does the abducens nerve originate and what is its pathway to the orbit?

Answer 38

The abducens nerve originates from the pontomedullary junction, passes through the cavernous sinus, through the superior orbital fissure and terminates in the lateral rectus muscle.

Question 39

What does the abducens nerve control?

Answer 39

The abducens nerve controls the lateral rectus muscle - outward gazing.

Question 40

What kind of fibers is the abducens nerve?

Answer 40

The abducens nerve is a motor nerve with GSE fibers.