Lab 3 Cranial Nerve Function

what is the anatomical explanation for why humans have sharper vision in the central aspects of their visual fields than in the peripheral visual fields?

cones in the central retina

fovea centralis

found in the center of the macula lutea. anything you want to view well you focus here. has the most cones

which 2 cranial nerves does the pupillary light reflex asses?

CN II and CN III

when assessing a subject's ability to visually track a moving finger, it is discovered that the subject's right eye is unable to follow the movement of the finger as it moves to the right side of the subject's head. which cranial nerve(s) might be responsible for this problem?

CN III, IV, VI

the corneal reflex, in which touching the cornea of one eye causes both eyes to blink, is used to assess which cranial nerves? why are we not performing that in today's lab?

CN V and CN VII, not doing it for hygienic reasons

"ask the subject to smile broadly. record any asymmetry or drooping in the face." what cranial nerve is this assessing?

CN VII, Facial Nerve

an individual is asked to smile broadly. it is observed that the left corner of the mouth cannot be elevated normally. when asked to wrinkle the brow, it is normally. which cranial nerve is involved in this facial control issue, and is the lesion in that nerve, or within the CNS?

CN VII, central lesion

during a neurological exam, a subject attempts to shrug his/her shoulders into the resistance of the physician's hands pressing down. the physician notes that while the right shoulder overcame resistance easily, and left shoulder seemed weaker. this sign is consistent with a lesion in which cranial nerve?

CN XI (accessory), left side

During a neurological exam, a subject attempts to shrug his/her shoulders into the resistance of the physician's hands pressing down. The physician notes that while the right shoulder overcame the resistance easily, the left shoulder seemed significantly weaker. This sign is consistent with a lesion in which cranial nerve?

CN XI, accessory nerve, left side

CN IX

glossopharyngeal nerve, motor to muscles of pharynx, salivary glands; sensory for taste

CN XII

hypoglossal nerve, motor to tongue muscles

CN VI

abducens nerve, motor to muscles that move eyeball

CN XI

accessory nerve, motor to neck and back muscles

optic disc

blind spot, where the optic nerve leaves the eye. area of retina where there are not rods and cones. anything focused here cannot be seen

what is a consensual reflex?

both eyes respond when you shine light into one eye

differences in central and peripheral vision

central vision involves the cones and and peripheral vision involves the rods

during a neurological exam a hearing deficit is detected in an individual's left year. when asked to hum the individual reported that the humming was especially loud on the left side. what type of hearing deficit is this person experiencing?

conduction deficit, left side

interpreting a Snellen Eye Chart

ex: someone who scored a 20/200 means that the smallest line on the chart that you can read at 20 feet, a person with perfect vision can read that at 200 feet.

CN VII

facial nerve, motor to muscles of facial expression, controls tears and salivation, sensory for taste

hyperopia

farsightedness, objects are focused behind the retina either because the eyeball is too short or lens is lazy

myopia

nearsightedness, objects are focused in front of the retina either because the eyeball is or too long or lens is too strong

pupillary light reflex

normal constriction of pupils when bright light shines on retina, involves CN II and CN III

conduction deficit

occurs when sound vibrations can't be conducted to the inner ear along the normal conduction pathway.

Light is shined into the right pupil, and only the right pupil constricts. Then light is shined into the left pupil and only the right pupil constricts. This pattern is consistent with a lesion to which cranial nerve? Name the nerve and the side.

oculomotor nerve, left side

CN III

oculomotor nerve, motor to muscles that move eyeball, constricts pupil

CN I

olfactory nerve, sensory for smell

CN II

optic nerve, sensory for vision

In protocol two, The Blind Spot Test, what must be done to the paper containing the X and the dot mark when the right eye is covered?

paper must be flipped over

Describe a test to assess the function of the olfactory nerve. Why are we not doing that in our lab?

plug one of your nostrils and have them try to smell the odor. Nor doing it for sanitary reasons

what does it mean if someone's vision is described as being 20/15 according to the Snellen eye chart?

this person can read the bottom line of the chart clearly at 20 feet when a person with perfect vision can only read at 15 feet away. this person has myopia and can see shorter distance than the average person

Although the cold caloric test, in which cold water is introduced into the ear, can be used to assess the function of the vestibular portion of the vestibulocochlear nerve, what is that test more commonly used for?

to assess the level of consciousness

CN V

trigeminal nerve, sensory to face, motor to muscles of mastication

CN IV

trochlear nerve, motor to muscles that move eyeball

cones

type of photoreceptor, involved in color vision and are not sensitive to light

rods

type of photoreceptor, involved in dim vision and peripheral vision and see in shades of grey, sensitive to light

CN X

vagus nerve, sensory and motor to internal organs in thoracic and abdominal cavities

CN VIII

vestibulocochlear nerve, sensory for hearing and balance

nerve deficit

when there is damage to the neurons in the inner ear.