CRANIAL NERVES Flashcards
11th Cranial Nerve
11 Accessory
Neck turning and shoulder shrugging
The person is asked to turn the head and to shrug the shoulders against resistance provided by the examiner.
10th Cranial Nerve
10 Vagus Nerve
Swallowing, the gag reflex, and speech
Control of muscle in some internal organs (gastrointestinal) and the heart rate
12th Cranial Nerve
12 Hypoglossal
Tongue movement
The person is asked to stick out the tongue, which is observed for deviation to one side or the other.
1st Cranial Nerve
1 Olfactory
Smell
The ability to smell is tested by asking the person to identify items with very specific odors (such as soap, coffee, and cloves) placed under the nose. Each nostril is tested separately.
2nd Cranial Nerve
2 Optic
Vision
The ability to see is tested by asking the person to read an eye chart. Peripheral vision is tested by asking the person to detect objects or movement from the corners of the eyes.
Detection of light
The ability to detect light is tested by shining a bright light (as from a flashlight) into each pupil in a darkened room.
3rd Cranial nerve
3 Oculomotor
Eye movement upward, downward, and inward
The ability to move each eye up, down, and inward is tested by asking the person to follow a target moved by the examiner.
Narrowing (constriction) or widening (dilation) of the pupil in response to changes in light
The pupils’ response to light is checked by shining a bright light (as from a flashlight) into each pupil in a darkened room.
Raises the eyelids
The upper eyelid is checked for drooping (ptosis).
4th Cranial Nerve
4 Trochlear
Eye movement downward and inward
The ability to move each eye down and inward is tested by asking the person to follow a target moved by the examiner.
5th Cranial Nerve
5 Trigeminal
Facial sensation
Sensation in areas of the face is tested using a pin and a wisp of cotton.
The blink reflex is tested by touching the cornea of the eye with a cotton wisp.
Chewing
Strength and movement of muscles that control the jaw are tested by asking the person to clench the teeth and open the jaw against resistance.
6th Cranial Nerve
6 Abducens
Eye movement outward
The ability to move each eye outward beyond the midline is tested by asking the person to look to the side.
7th Cranial Nerve
7 Facial Cranial Nerve
Facial expression, taste in the front two thirds of the tongue, production of saliva and tears, and control of a muscle involved in hearing
The ability to move the face is tested by asking the person to smile, to open the mouth and show the teeth, and to close the eyes tightly.
Taste is tested using substances that are sweet (sugar), sour (lemon juice), salty (salt), and bitter (aspirin
, quinine
, or aloes).
8 Cranial Nerve
8 Auditory (vestibulocochlear)
Hearing
Hearing is tested with a tuning fork or with headphones that play tones of different frequencies (pitches) and loudness (audiometry).
Balance
Balance is tested by asking the person to walk a straight line.
9th Cranial Nerve
9 Glossopharyngeal
Swallowing, the gag reflex, and speech
Because both the 9th and 10th cranial nerves control swallowing and the gag reflex, they are tested together.
The person is asked to swallow. The person is asked to say “ah-h-h” to check movement of the palate (roof of the mouth) and uvula (the small, soft projection that hangs down at the back of throat).
The back of the throat may be touched with a tongue blade, which evokes the gag reflex in most people.
The person is asked to speak to determine whether the voice sounds nasal (another test of palate movement).
Cranial Nerves Mnemonic
Oh Oh Oh To Tickle A Female’s Vagina Gave Victor A Hard-on
1 Olfactory 2 Optic 3 Ocularmotor 4 Troclear 5 Trigeminal 6 Abducens 7 Facial 8 Vestibularcochlear 9 Glossopharangeal 10 Vagus 11 Accessory 12 Hypoglossal
CN X
Vagus nerve
The vagus nerve is one of 12 cranial nerves. It is the longest of the cranial nerves, extending from the brainstem to the abdomen by way of multiple organs including the heart, esophagus, and lungs. Also known as cranial nerve X, the vagus forms part of the involuntary nervous system and commands unconscious body procedures, such as keeping the heart rate constant and controlling food digestion.
Electrical stimulation of the vagus nerve, called vagus nerve stimulation (VNS), is sometimes used to treat people with epilepsy or depression.
The vagus nerve is involved in one of the most common causes of fainting, called vasovagal syncope. This is an overreaction of the body to certain stimuli, like the sight of blood, which involves the stimulation of the vagus nerve. This stimulation causes a drop in blood pressure and heart rate. Less blood flows to brain, resulting in loss of consciousness. In most cases, vasovagal syncope does not require treatment.
CN XI
Cranial Nerve XI: The Spinal Accessory Nerve
This nerve supplies the sternocleidomastoid and trapezius muscles, which have the following functions:
Rotation of head away from the side of the contracting sternocleidomastoid muscle.
Tilting of the head toward the contracting sternocleidomastoid muscle.
Flexion of the neck by both sternocleidomastoid muscles.
Elevation of the shoulder by the trapezius.
Drawing the head back so the face is upward by the trapezius muscles.
With weakness or paralysis these functions are decreased or absent. When the lesion is nuclear or infranuclear, there is associated muscle atrophy and fasciculations.
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