4-cranial Nerves.docx

CRANIAL NERVE I: OLFACTORY NERVE Close one of the patient’s nostrils with a finger Ask the patient if he can smell a strongly scented volatile substance such as coffee or lemon extract. The test is then repeated for the other nostril. Should sniff strongly to draw the volatile molecules well into the nose Testing substance should not produce a response due to chemical irritation of nasal mucosa [responses are due to stimulation of branches of the trigeminal nerve] For this reason, substances such as ammonia, perfumes (because of alcoholic content), and onions, although strongly scented, cannot be used to test for olfactory function

CRANIAL NERVE II: OPTIC NERVE: Tested by the investigation of visual acuity and the visual fields Visual acuity is tested with the familiar wall chartsnellen eyechart Field of vision: Confrontation test

CRANIAL NERVE III: OCULOMOTOR CRANIAL NERVE IV: TROCHLEAR CRANIAL NERVE VI: ABDUSCENS Concerned with the pupillary reflex (III), accommodations (III), and eye movements (III, IV, and VI) Tested simultaneously by examining the size, outline, and reaction of each pupil to light and dark and to accommodation for near and far vision

Cranial Nerve V: Trigeminal nerve: Significance— tested for both motor and sensory functions. Muscles of mastication: Palpation while patient clenches—the force of contraction and muscle bulk of the masseter and temporal muscles are noted by external palpation of these muscles bilaterally while the patient clenches. Lateral movement of the jaw against the examiner's finger is one test of pterygoid functions. Two reflexes:Corneal reflex, Jaw jerk reflexPlace a thumb on patient’s chin, just below lower lip. Sharply tap the thumb with a percussion hammer or with fingers of the other hand. The patient’s jaw should close. Displacement against resistance-to check their ability to carry out voluntary displacement of the jaw against the imposed resistance of the examiner's hand. The patient is asked to move the jaw forward, sideways and upward his head steadied by your other hand-weakness in movement assessed. Sensory function of the trigeminal nerve: corneal reflex to touch (ophthalmic division) Instruments for the testing of trigeminal sensory function Graded Frey’s hairs Two-point esthesiometers Calibrated thermal devices for the application of hot and cold Taste testing

Cranial Nerve VII: Facial nerve: Motor function test— Ask the patient to smile, to wrinkle the forehead, frown, whistle, blow out the cheek, close the eyelid tightly, raise each eyebrows Unilateral facial paralysis, but raise both eyebrowsUMN lesion If eyebrow on affected side cannot be raised -LMN

Cranial Nerve VIII: Vestibulocochlear nerve: Hearing & balance Acoustic nerve function includes both cochlear (hearing) and vestibular (balance) components, which are physiologically distinct and which are tested separately Simple tests for vestibular function include the past-

lesion Test for taste perception: Apply the test solution of four primary tests(sweet, salt, sour, bitter) to the lateral borders of anterior two-thirds of the tongue Ask the patient to identify the taste.

pointing test and assessment for the eye movements that are characteristic of nystagmus when the patient is asked to look to one side and then upward Hearing may be tested at three levels : By observing the patient’s ability to hear (a) normal speech and a whisper or (b) the ticking of a watch held at varying distances from each ear By holding one or more tuning forks near each ear, on the mastoid process, and on the forehead (allowing separation of nerve and conduction deafness as well as identification of unilateral defects) By audiometric testing (the most precise method)

Cranial Nerve IX (Glossopharyngeal Nerve). Gag reflex, taste sensation The glossopharyngeal nerve provides taste fibers to: The posterior aspect of the tongue Somatic sensory fibers to the same area of the tongue as well as to the pharynx and soft palate (tested along with sensory function of cranial nerve X Motor fibers to the stylopharyngeus muscle, which plays only a minor role in palatal function. Thus, any accurate testing of cranial nerve IX motor function is impossible.

Vagus Nerve Pharyngeal movements, gag reflex Pharyngeal movement observation — symmetrical elevation of the soft palate and shortening of the uvula when the patient says 'ah' Pharyngeal and gag reflex, i.e. contraction of the palate and faucial muscles in response to touching the mucous membrane of the posterior pharynx.

Cranial Nerve XI (Accessory Nerve). The spinal accessory nerve is tested through its motor supply to the trapezius and sternomastoid muscles. For the trapezius, ask the patient to shrug his or her shoulders against the resistance of your hands For the sternomastoid, have the patient turn and flex the head against the same resistance

Hypoglossal nerve Tongue movement Ask the patient to protrude the tongue. If damaged unilaterally, tongue will deviate to the damaged side.

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Neurological Assessment. (1) Mental status. level of consciousness and orientation to time, place, and person. Altered states of consciousness are: (a) Conscious--Alert, awake, aware of one's self and environment.

(b) Confusion--Disorientation in time. Irritability and/or drowsiness. Misjudgment of sensory input. Shortened attention span. Decrease in memory. (c) Delirium--Disorientation, fear. Misperception of sensory stimuli. Visual and auditory hallucinations. Loss of contact with environment. (d) Stupor--Unresponsive, but can be aroused back to a near normal state. (e) Coma--Unresponsive to external stimuli. (4) Sensation. The sensory functions include touch, pain, vibration, position, temperature, and discrimination. If the patient complains of numbness, peculiar sensations, or paralysis, sensation should be checked more carefully over flexor and extensor surfaces of the extremities. Generally the face, arms, legs, hands, and feet are tested for touch and pain. (a) Touch: wisp of cotton. Ask the patient to close his eyes and respond whenever the cotton touches his skin. Compare the sensation in symmetrical areas of the body, such as the cheeks. (b) sharpness or dullness of pain: blunt end of a safety pin. (c) sense of vibration: tuning fork held firmly against a bone. [ the thumb side of the wrist, the outside of the elbow]. (e) Temperature sensation: tubes filled with hot and cold water (f) ability to discriminate : stereognosis (the ability to recognize objects by touching them like coin, paper clip, or key in the patient's hand and ask him to identify it. one- and two-point stimuli. Alternate touching the patient's fingertip with two pinpoints simultaneously and then with one pin. Have the patient discriminate between the one- and two-point stimuli.