7 CN I, II, III, IV, VI

Question 1

CN I
Axon:
CNS Origin/Termination:
Peripheral Origin/Termination:

Answer 1

Axon: SSA
CNS: Olfactory bulb
Per: Olfactory epithelium

Question 2

This CN is in charge of olfaction (taste/smell)

Answer 2

CN I

Question 3

Pain in Olfactory epithelium is detected by this CN/nucleus

Answer 3

CN V (spinal trigeminal nucleus)

Question 4

Thinnest and slowest axons in human body are _____. They collect into a series of bundles called _____.

Answer 4

Olfactory axons

Olfactory fila

Question 5

Olfactory bulb and tract develop as outgrowths of the _____. This tract reaches ipsilateral hemisphere with no relay in the ____.

Answer 5

Telencephalon

Thalamus

Question 6

Each type of olfactory receptor sends an axon to one ____ of a ____ cell.

Answer 6

Glomerulus

Mitral

Question 7

Processes olfactory sensory information

Answer 7

Pyriform area

Question 8

Creates emotional response to smell

Answer 8

Medial Olfactory Stria

Question 9

CN II

1. Axon:
2. CNS Origin/Termination:
3. Peripheral Origin/Termination:

Answer 9

1. SSA
2. Lateral geniculate nucleus (thalamus), superior colliculus, hypothalamus (circadian rhythm)
3. Retinal ganglion cells

Question 10

The lens accounts for ___ of the eye’s refractive power (especially good to adjust for up close [reading] vision). Most refraction is at the ____ surface.

Answer 10

1/3

Corneal

Question 11

Visual protein. Low-acuity, monochromatic vision in dim-light.

Answer 11

Rods

Question 12

Visual protein. High acuity, color vision, need lots of light.

Answer 12

Cones

Question 13

Damage anterior to optic chiasm only affects _____

Answer 13

Ipsilateral eye

Question 14

Damage at optic chiasm causes

Answer 14

Heteronymous Deficits (lose peripheral vision/nasal tracts-> tunnel vision)

Question 15

Damage to optic tract (posterior to chiasm) causes _____

Answer 15

Homonymous Deficits (lose right or left side vision in both eyes = lose right or left visual field)

Question 16

Results of CN III injury

Answer 16

1. Affected eye is “down and out” (direction pointed because of weak medial and superior rectus)
2. Diplopia (Double Vision)
3. Dilated pupil
4. Lens can’t focus

Question 17

Only CN that decussates

Answer 17

IV (Trochlear)

Question 18

This CN controls the superior oblique which moves eye downward and laterally (and internal rotation/intorsion) Injured -> diplopia when going downstairs or reading

Answer 18

CN IV Trochlear

Question 19

This CN innervates ipsilateral lateral rectus, which abducts the eye.

Answer 19

CN VI Abducens

Question 20

Because of CN VI long intracranial course, it is susceptible to increased _____

Answer 20

Intracranial pressure

Question 21

Injury to CN VI causes:

Answer 21

Medial strabismus (affected eye deviates medially)

Question 22

The _____ interconnects CN III, IV, and VI nuclei to coordinate head and eye movement. Motor neurons and internuclear neurons from these nuclei ascend in this structure.

Answer 22

Medial Longitudinal Fasciculus (MLF)

Question 23

Eye movement types:

Answer 23

1. Scanning- eyes move from one visual target to another in high-speed movement known as saccades
2. Tracking- smooth pursuit, eyes follow target
3. Compensation- gaze held on target during head movement (vestibulo-ocular reflex)

Question 24

CN III innervation and function:

Answer 24

1. Superior rectus -> elevation
2. Inferior rectus -> depression
3. Medial rectus -> adduction
4. Inferior oblique -> external rotation (extorsion))

Question 25

CN III 1. Axon types 2. CNS origin 3. Peripheral termination

Answer 25

1. GSE 2. Oculomotor nucleus (rostral midbrain) 3. Superior, inferior, medial recti; inferior oblique, levator palpebrae, superioris muscles 1. GVE 2. Edinger-Westphal nucleus (in above) 3. Ciliary ganglion, sphincter pupillae muscle (parasympathetic - decreases pupil size for near vision)

Question 26

CN IV 1. Axon types 2. CNS origin 3. Peripheral termination

Answer 26

1. GSE 2. Trochlear nucleus (caudal midbrain) 3. Superior Oblique muscle

Question 27

CN VI 1. Axon types 2. CNS origin 3. Peripheral termination

Answer 27

1. GSE 2. Abducens nucleus (caudal pons) 3. Lateral rectus muscle

Question 28

Each side of CN II is connected to both sides of CN III at the _____. -> Light shined in one eye causes constriction of BOTH pupils

Answer 28

Edinger-Westphal nucleus.

Question 29

CN III nucleus is located in this section of the brainstem:

Answer 29

Rostral Midbrain (medial)

Question 30

Trochlear nucleus (IV) is located in this section of the brainstem:

Answer 30

Caudal Midbrain (medial)

Question 31

Abducens nucleus (VI) is located in this section of the brainstem:

Answer 31

Caudal pons (medial)