Cranial nerves adi

Taste in anterior two-thirds of tongue This test assesses the special sensory nerve fibers of the facial nerve that provide taste to the anterior two-thirds of the tongue. Exam Keep the salt and sugar samples out of sight of the volunteer. Instruct the volunteer to close their eyes. Place a small amount of salt in one of the volunteer's hands and sugar in the other. Remember which hand contains the salt and which contains the sugar. Instruct the volunteer to taste both samples and report which one is salt and which is sugar.

Taste in anterior two-thirds of tongue Normal results The volunteer should be able to correctly determine which sample is the salt and which is the sugar. The volunteer should be able to taste the salt and/or sugar on both halves of their tongue. Abnormal results Absence of taste in any part of the anterior two-thirds of the tongue. Damage to either facial nerve will result in ipsilateral loss of taste in the tongue. Damage to both facial nerves will result in bilateral loss of taste in the tongue.

Nerve assessment Perform the following assessments to test the function of the volunteer's cranial nerve! Shoulder and head movement This test assesses the motor pathway of the accessory nerve that allows us to shrug our shoulders and turn our heads. Exam Ask the volunteer to sit in a chair with their feet flat on the floor. The experimenter will then gently press down on the volunteer's shoulders. Instruct the volunteer to shrug their shoulders to see if they can overcome the resistance applied by the experimenter. In the table, record whether or not the volunteer was able to overcome the resistance. The experimenter will now place their hand on the right side of the volunteer's head. Instruct the volunteer to turn their head to the right to see if they can overcome the gentle resistance applied by the experimenter. Repeat the step above, but this time on the left side of the volunteer's head. In the table, record whether or not the volunteer was able to overcome the resistance on both sides. Report the results of this test. Was each member of your group able to overcome the resistance applied by the experimenter?

Shoulder and head movement Normal results The volunteer should be able to overcome the gentle resistance placed on their shoulders and on the side of their head. Abnormal results Inability to overcome the gentle resistance applied to the shoulders.This result suggests damage to the branch of the accessory nerve that innervates the trapezius on the same side. Inability to overcome the gentle resistance applied to the side of the head. This result suggests damage to the branch of the accessory nerve that innervates the sternocleidomastoid on the same side. Inability to overcome the gentle resistance applied to the shoulders and the side of the head suggests a complete severing of the accessory nerve.

cranial nerve 10

X. Vagus nerve

the oculomotor nerve innervates the

rest of the extraocular muscles

cranial nerves

12 pairs of nerves that carry messages to and from the brain

Balance test This test assesses the vestibular branch of the vestibulocochlear nerve. Exam Ask the volunteer to stand somewhere where they can walk in a straight line. Instruct the volunteer to walk forward in a heel-to-toe manner in a straight line. If the volunteer can easily perform the step above, ask them to repeat the heel-to-toe walk, but this time with their eyes closed.

Balance test Normal results Ability to walk in a heel-to-toe manner in a straight line with eyes open with relative ease. Removing visual feedback will make the task more difficult, but it should still be relatively easy to complete. Abnormal results Falling over and/or inability to maintain a straight line while walking heel-to-toe.This result indicates damage to the vestibular branch of the vestibulocochlear nerve or to the semicircular canals of the inner ear. Note: Swaying is not an abnormal result because it indicates proprioceptive correction by the volunteer.

Corneal reflex This test assesses both the trigeminal nerve and the facial nerve. The sensory information is detected by the trigeminal nerve, while the facial nerve provides the motor stimulus to blink.

Corneal reflex Normal results A forceful blink when the cotton swab touches the cornea. The trigeminal nerve (CN V) is the afferent pathway of the corneal reflex that carries the light impulse to the trigeminal nucleus. Here, the fibers synapse with the efferent pathway. The efferent impulse is carried by the facial nerve (CN VII), causing you to blink. Abnormal results No blink occurs when the cornea is touched but the volunteer does feel the cotton swab.This reaction indicates damage to the efferent pathway (CN VII). The volunteer does not feel the cotton swab but still blinks when the cornea is touched.This reaction indicates damage to the afferent pathway (CN V).

Exam Position the experimenter and the volunteer so that they sit facing each other. Instruct the volunteer to follow the tip of the experimenter's finger with their eyes while keeping their head still. The experimenter will then move their finger horizontally, vertically, and diagonally. Observe the volunteer's eye movements and notice if there are any involuntary, abnormal, or absent eye movements.

Eye movement Normal results The volunteer's eyes should move together in all directions (up and down, left and right, and diagonally). Abnormal results The inability to move one or both eyes in any direction indicates an abnormality. A nerve or brainstem lesion, or a tumor, could all lead to the inability to move one or both eyes synchronously in any direction.

Nerve assessment Perform the following assessments to test the function of the volunteer's cranial nerve! Hearing test This test assesses the special sensory nerve fibers of the cochlear branch of the vestibulocochlear nerve. Exam Ask the volunteer to sit still with their eyes closed. Instruct the volunteer to raise their hand on the same side that they hear the experimenter make a sound. Rub your fingers together to make a sound near one of the volunteer's ears and wait for them to respond. Be careful not to touch the volunteer. Repeat this procedure a few times randomly for each ear. Ask the volunteer if the sound was the same loudness in each ear.

Hearing test Normal results The volunteer should be able to hear the sound at equal strength in both ears. Abnormal results Absence of hearing or reduced hearing in either ear. If absent or reduced hearing is detected during this test, the Weber and Rinne tests are used to determine the source of hearing loss (neural or structural).

cranial nerve 1

I. Olfactory nerve

cranial nerve 2

II. Optic nerve

cranial nerve 3

III. Oculomotor nerve

cranial nerve 4

IV. Trochlear nerve

cranial nerve 9

IX. Glossopharyngeal nerve

Nerve assessment Perform the following assessments to test the function of the volunteer's cranial nerve! Muscles of facial expression This test assesses the motor components of the facial nerve that allow us to make facial expressions. Exam Before you perform a formal assessment, observe the volunteer's face during conversation and at rest. Notice any facial asymmetry. Ask the volunteer to raise both eyebrows, furrow both eyebrows, smile, frown, show both upper and lower teeth, and puff out both cheeks. Tightly close both of your eyes and keep them closed. Gently attempt to open your eyes using your fingers. Do not attempt to do this on another person. Notice any discrepancies in facial movement bilaterally as you and the volunteer carry out these maneuvers.

Muscles of facial expression Normal results Bilateral facial movement in the forehead, cheeks, and chin. Movement should not be difficult to produce. Abnormal results Facial drooping or inability to produce bilateral facial movements. If a branch of the facial nerve is severed or damaged, then the muscles in the region that branch innervates will be unresponsive. For example, raising the eyebrow will not be possible for a patient with a severed temporal branch of the facial nerve.

Muscles of mastication This test assesses the motor component of the trigeminal nerve that innervates the muscles of mastication. Exam Sit the volunteer in a chair. Instruct the volunteer to clench their jaw. Palpate the masseter and temporalis muscles. In the table, note any atrophy that has occurred in either muscle. The masseter will fatigue quickly if the volunteer clenches their jaw for too long. Next, ask the volunteer to open their jaw. Apply a light pressure upward as if to shut the volunteer's mouth, and instruct the volunteer to keep their jaw open against the pressure. In the table, record whether the volunteer was able to resist the upward pressure. Test multiple people in the group.

Muscles of mastication Normal results The masseter and temporalis muscles should indicate full strength throughout the entire muscle. The volunteer should have no trouble keeping their mouth open against the force applied by the experimenter. Abnormal results Atrophy of either the masseter or temporalis. The inability of the volunteer to maintain a clenched jaw or resist the force applied by the experimenter. Abnormal results on either side of the face indicate that the motor component of the trigeminal nerve is compromised.

Pharyngeal (gag) reflex This test assesses the sensory pathway of the glossopharyngeal nerve and the motor pathway of the vagus nerve that cause us to experience a gag reflex. Do not perform this test on yourself or your group members. Simply watch the video to see what the gag reflex is.

Pharyngeal (gag) reflex This test assesses the sensory pathway of the glossopharyngeal nerve and the motor pathway of the vagus nerve that cause us to experience a gag reflex. Do not perform this test on yourself or your group members. Simply watch the video to see what the gag reflex is.

Nerve assessment Perform the following assessments to test the function of the volunteer's cranial nerve(s)! Pharyngeal (throat) movement This test assesses the motor components of the glossopharyngeal and vagus nerves that innervate the muscles of the pharynx (throat). Exam Ask the volunteer to swallow and observe if they have any difficulty in doing so. Then ask them if they have any difficulty swallowing. Next, instruct the volunteer to open their mouth and stick out their tongue. Ask the volunteer to say "ahhhh" and use the tongue depressor to hold down the tongue. Observe the volunteer's soft palate, uvula, and pharynx. You may need to use a light to get a good view. © Did anyone in your group exhibit any asymmetrical throat movements during this test? If yes, describe the asymmetry and which side was affected.

Pharyngeal (throat) movement Normal results The soft palate should rise symmetrically, the uvula should remain in the midline, and the pharynx (throat) should constrict medially, like a curtain. Abnormal results Asymmetrical movement in the throat. Deviation of the uvula from the midline. Damage to either the glossopharyngeal or vagus nerve would result in an ipsilateral lack of movement in the throat.

Pupillary light reflex This test assesses the parasympathetic innervation of the pupil by the oculomotor nerve. The ability of our eyes to adapt to light is controlled by the size of the pupil. Exam Ask the volunteer to sit and look at a fixed point in front of them. Observe the diameter of the volunteer's pupils prior to the test. Are they the same on both sides? Shine the pen light into the right eye and observe the pupillary response of each eye. In the table, record the responses of both the eye that the light was shone into, and the opposite eye. Repeat this test for the left eye

Pupillary light reflex Normal results Both pupils should constrict when a light is shined into either eye. The neural pathway for the pupillary light reflex on each side has one afferent pathway and two efferent pathways. The optic nerve (CN II) is the afferent pathway that carries the light impulse to the midbrain near the superior colliculli. Here, the fibers synapse with the efferent pathway. The efferent pathway carries the signal by way of the oculomotor nerve (CN III) to cause bilateral constriction of both pupils. Abnormal results Absent pupillary response on the same side as the light stimulus. Present pupillary response on the contralateral side.This response indicates that the afferent pathway (CN II) is intact but the efferent pathway (CN III) on the ipsilateral side is damaged. Absent pupillary response on the contralateral side to the light stimulus. Present pupillary response on the ipsilateral side.This response indicates that the afferent pathway (CN II) is intact but the efferent pathway (CN III) on the contralateral side is damaged. Absent pupillary response bilaterally with light stimulus.This response indicates a damaged afferent pathway (CN II), preventing the signal from reaching either efferent pathway (CN III).

Rinne test This test assesses unilateral hearing loss by comparing the perception of sounds transmitted through air conduction and those transmitted through bone conduction. Exam Tap the tuning fork strongly on your palm. Immediately and firmly, press the handle of the tuning fork to the volunteer's mastoid process (bony process posterior to the ear). Instruct the volunteer to say "now" when they can no longer hear the sound. When the volunteer says "now", remove the tuning fork and, without retapping it, hold the prongs close to the volunteer's ear. Instruct the volunteer to again say "now" when they can no longer hear any noise.

Rinne test Normal results Air conduction should be greater than bone conduction. The volunteer should still be able to hear the tuning fork through air conduction after they stop hearing it through bone conduction. Abnormal results Inability to hear the tuning fork after it is removed from the mastoid and held near their ear means bone conduction is greater than air conduction. This result indicates problems transmitting sound waves through the bones of the middle ear, and there is said to be conductive hearing loss. Diminished ability to hear the tuning fork while on the mastoid and after it has been removed (that is, indicating that the sound has stopped when it is still audible to a normal ear).This result indicates sensorineural hearing loss.

Sensation in the face This test assesses the sensory components of the trigeminal nerve that provide sensation to various regions of the face. Exam Ask the volunteer to sit in a comfortable position with their eyes closed. Use a cotton swab to gently stroke the volunteer's skin on their forehead and nose bridge. This is the area innervated by V1 (ophthalmic branch). Stroke the skin under the eyes and along the upper lip. This is the area innervated by V2 (maxillary branch). Stroke the skin in front of the ears and along the chin. This is the area innervated by V3 (mandibular branch). In the table, record whether the volunteer did or did not feel the cotton swab in each of the three regions.

Sensation in the face Normal results The volunteer should be able to feel sensation in all three regions of the face innervated by the branches of the trigeminal nerve (on both sides of the face). Abnormal results The inability to feel in any region suggests damage to the corresponding sensory branch of the trigeminal nerve. Inability to feel on one side of the face indicates that the ipsilateral trigeminal nerve is affected.

Sense of smell This exam assesses the special sensory fibers of the olfactory nerve. It is used to test whether a patient's sense of smell is intact and whether the scent is detected to be of equal strength bilaterally. Unless someone complains about their sense of smell when they go to the doctor, this test is usually skipped during a typical cranial nerve exam. Exam Instruct the volunteer to block one nostril and breathe through the other nostril to establish patency. Ask the volunteer to close their eyes. Instruct the volunteer to breath normally through their open nostril and inform you when they smell something. Hold an odorant near the volunteer's nostril. Repeat the test with the other nostril. Ask the volunteer if the smell was of equal strength in both nostrils. Test other members of the group.

Sense of smell Normal results The volunteer should be able to identify the odorant without any verbal cue. The strength of smell should be equal in both nostrils. Abnormal results Loss of sense of smell in either or both nostrils. Unequal strength of smell between sides. Bilateral loss of smell can occur with rhinitis, smoking, and/or aging. Unilateral loss of smell can suggest a nerve lesion or deviated septum.

Nerve assessment Perform the following assessments to test the function of the volunteer's cranial nerve! Tongue movement This test assesses the motor pathway of the hypoglossal nerve that allows us to move our tongues. Exam Ask the volunteer to stick their tongue out and move it from side to side. Observe if there are any deviations of the tongue from the midline, or any inabilities to manipulate the tongue.

Tongue movement Normal results The tongue should remain in the midline when stuck out and should be easy for the volunteer to control. Abnormal results Inability to stick out tongue. Tongue atrophy. Deviations of the tongue from the midline. A peripheral lesion of the hypoglossal nerve will result in the tongue deviating toward the same side as the lesion.

cranial nerve 5

V. Trigeminal nerve V1. Ophthalmic branch V2. Maxillary branch V3. Mandibular branch

cranial nerve 6

VI. Abducens nerve

cranial nerve 7

VII. Facial nerve

cranial nerve 8

VIII. Vestibulocochlear nerve

Visual acuity test This test is used to assess special sensory nerve fibers of the optic nerve. This exam is performed to gauge a person's ability to discern the shapes and details of the various things they see. Visual acuity refers to a person's clarity of vision. Exam If the volunteer wears glasses or contacts, they should keep them on during this test. Position the volunteer 2.8 m (9.19 feet) from the visual acuity eye chart. Ask the volunteer to cover their right eye. Instruct the volunteer to read from the top line, then down the chart as far as they can. Follow the volunteer's progress to check their accuracy. Repeat the test with the volunteer's left eye covered. Note the visual acuity for each eye in the table.

Visual acuity Normal results 20/20 (row 8) is considered normal vision for the average person. Having 20/20 vision indicates that you can see an object with normal clarity and sharpness standing 20 feet from that object. Abnormal results 20/40 vision means you must stand 20 feet away from an object to see the same amount of detail that a person with 20/20 vision can see at 40 feet. 20/15 vision means that you can see at 20 feet what the average person can see at 15 feet. Blurred vision in most people is usually caused by abnormal eye shapes.

Visual field test This test is used to assess special sensory nerve fibers of the optic nerve. The exam estimates the boundaries of a person's peripheral (side) vision. Exam Position the experimenter and volunteer so that they sit facing each other. Instruct the volunteer to cover one eye and look at the experimenter's nose throughout the test. The experimenter will now hold one finger to the side of the visual field, out of sight. Slowly move the finger toward the volunteer's peripheral vision, and ask them to indicate when they see the finger. Repeat this test for the other eye. In the table, record the estimated angles of the volunteer's visual field in both eyes. Give your best guess of the angles based on the patient's gaze forward being zero degrees. Test multiple people in the group.

Visual field Normal results A normal visual field is considered to be within a range of up to 95 degrees temporally (toward the ear) and 60 degrees nasally (toward the nose). Abnormal results A decreased field of vision indicates damage to some part of the visual system. Abnormal results may be due to a disorder affecting the central nervous system, which may in turn affect various structures of the visual system. Some of these diseases include: Diabetes Glaucoma Multiple sclerosis Retinal detachment Stroke Tumors

Weber test This test assesses conductive hearing loss by testing the skull's ability to conduct sound to the bones that make up the middle ear, which allow us to hear noise. Exam Tap the tuning fork strongly on your palm. Immediately and firmly, press the handle of the tuning fork to the top of the volunteer's head along the midline. Ask the volunteer where they hear the sound. 12... 6seek to 10%, 20% ... 60% Record whether or not the sound was heard in both ears for each volunteer tested.

Weber test Normal results The volunteer should report hearing the sound equally in both ears. Some people report hearing the sound in the middle of their head. Abnormal results If it is already known which ear is affected: Conductive hearing loss is indicated when the defective ear hears the tuning fork more loudly than the unaffected ear. Sensorineural hearing loss is indicated when the unaffected ear hears the tuning fork more loudly than the affected ear. If it is unknown which ear is affected, the Rinne test is used to help determine the cause of hearing loss.

cranial nerve 11

XI. Accessory nerve

cranial nerve 12

XII. Hypoglossal nerve

sensorineural hearing loss

caused by damage to hearing organ, cochlea, or vestibulocochlear nerve ***

From which part of the brain does the olfactory nerve emerge?

forebrain

from which part of the brain does the optic nerve emerge

forebrain

conductive hearing loss

form of hearing loss that occurs when there is a problem transmitting sound waves through the bones (ossicles) in the middle ear

From which part of the brain does the abducens nerve emerge?

inferior border of the pons along the midline

olfactory bulb shape

large # of cell bodies concentrated within. olfactory bulb is considered the nucleus for the olfactory nerve bc it is where the nerves first synapse.

the abducens nerve innervates the

lateral rectus muscle

use anatomical terms to explain the location of the optic nerve nucleus (the lateral geniculate nucleus) within the brain

located within the lateral thalamus , very close to the cerebral aqueduct. the lateral geniculate is more superior than most of the other cranial nerve nuclei

from which part of the brain foes the hypoglossal nerve emerge

medulla oblongata between the pyramid and the olive

explain location of facial nerve nuclei

motor nuclei of facial nerve: inferior portion of the pons sensory nucleus of facial nerve: the solitary nucleus: inferior within the medulla oblongata

What happens at the optic chiasm?

nerve fibers from each eye cross to the other side of the brain. specifically, the signals received from the medial retina (later visual field) cross over

which branch of the trigeminal nerve is assessed by the corneal relex

ophthalmic branch V1 provides sensation to the eye

where does pipe cleaner to identify pathway of optic nerve

optic canal

the lateral retina of the left eye receives visual stimulus from which side of the visual field?

right visual field

the trochlear nerve innervates the

superior oblique muscle

the oculomotor, abducens, and trochlear nerves all exit the skull through the

superior orbital fissure

from which part of the brain does the accessory nerve emerge

superior spinal cord

Think about which nerves innervate which oculomotor muscles. If a patient is unable to move their eye laterally, which nerve would you suspect to be damaged?

the abducens nerve innervates the lateral rectus muscle

from which part of the brain does the facial nerve emerge?

the brainstem at the junction between the pons and medulla

from which part of the brain do the glossopharyngeal and vagus nerves emerge?

the lateral aspect of the medulla oblongata

from which part of the brain does the trigeminal nerve emerge?

the lateral aspect of the pons

which branch carries motor impulses to the muscles of mastication? these impulse originate in the motor nucleus of the trigeminal nerve located in the pons

the mandibular branch V3

From which part of the brain does the oculomotor nerve emerge?

the midbrain near the maxillary bodies

From which part of the brain does the trochlear nerve emerge?

the posterior surface of the midbrain

Where does the olfactory nerve exit the skull?

tiny holes in cribriform plate