Cranial nerve practical

physiology

1. EXAMINATION OF CRANIAL NERVES

2. CRANIAL NERVES I. Olfactory II. Optic III. Oculomotor IV. Trochlear V. Trigeminal VI. Abducent VII Facial VIII Vestibulocochlear IX Glossopharyngeal X Vagus XI Accessory XII Hypoglossal

3. The olfactory, optic and vestibulocochlear nerves are entirely sensory The occulomotor, trochlear, abducent, accessory and hypoglossal nerves are entirely motor The remaining nerves are mixed nerves.

4. 1. OLFACTORY NERVE Function – sense of smell Test each nostril separately with other nostril and eye closed. Use familiar materials like orange peel, coffee powder, soap, toothpaste , etc.

5. 11. OPTIC NERVE Function – vision Compone n ts of examina t io n - Acuity of vision Field of vision Color vision

6. VISUAL ACUITY Visual acuity recorded according to formula V=d/D, where d is distance at which patient can read the letter and D is the distance at which letters are readable by a person with normal vision .

7. VISUAL FIELD Confrontation test- examiner sits one meter away facing the patient whose right eye is tested with examiners left eye and vice versa. The other eye is kept covered self by the corresponding hands of the examiner and the patient. Differing numbers of fingers of examiner are presented in different quadrants of visual field from extreme periphery .

8. COLOR VISION Ishihara pseudoisochromatic eye plates are used in older children. Child is asked to identify the number produced by virtue of different colors.

9. PUPIL EXAMINATION Size, shape and pupillary reflexes Test – patient should be looking into distance. Bring the light beam directed to pupil from periphery. Sudden constriction of pupil occurs (direct response). Repeat the test , this time looking at the contralateral pupil, which will normally constrict Accomodation reaction – hold up a pen close to patients nose. Ask patient to look away and then quickly at the pen. As eyes converge, pupils constrict.

10. 111.OCCULOMOTOR, 1V.TROCHLEAR, V1.ABDUCENT NERVES Function – eye movements Test – observe the eye movements when a colored object is moved in various directions of visual field. Above age of 4 years child is asked to look at a red pen as it is moved in direction of action of extraocular muscles Doll’s eye movement phenomenon is used to test ocular movements in infants

11. Extraocular muscles 4 Recti and 2 Obliques Superior rectus Inferior rectus Medial rectus Lateral rectus Superior oblique Inferior oblique

12. V. TRIGEMINAL NERVE Function – sensory to face and eyes, motor to muscles of mastication Corneal and conjunctival reflex Sensory ‐ test sensations over forehead, cheeks and chin ( ophthalmic, maxillary and mandibular divisions) Motor ‐ ask to clench the teeth and palpate over the cheek and temple (masseters & temporalis ) ‐ ask to open the mouth wide ‐ jaw deviates to the paralyzed side (pterygoid)

13. VII. FACIAL NERVE Function – Motor to facial muscles, Taste sensation to anterior 2/3 of tongue Motor ‐ raise the eyebrows (frontalis) –wrinkling try to open tightly closed eyes ( orbicularis oculi ) obliteration of nasolabial fold on paralyzed side look for deviation of angle of mouth blowing of air ( buccinators) Sensory ‐ test for taste in the anterior 2/3 rd of tongue

14. VIII. VESTIBULOCOCHLEAR NERVE Function – sound perception and maintenance of body balance Hearing assessment Ask for tinnitus Rinne’s test Weber ‘ s test

15. I X & X ‐ GLOSSOPHAR Y NGEA L AND VAGUS NERVE Function – IXth: motor for stylopharyngeus muscle and middle pharyngeal sphinctor, sensory to posterior 1/3 of tongue Xth: Motor for soft palate,pharynx,larynx , sensory and motor for respiraory passage, heart and most of abdominal viscera

16. Gag reflex – tickle the posterior pharyngeal wall and look for contraction of pharynx ‐ afferent is IX and efferent is X Sensory – taste in posterior 1/3 of tongue

17. XI. ACCESSORY NERVE Trapezius muscle Tested by shoulder shrugging against resistance Drooping of shoulder on paralyzed side and scapula drop to lower level Sternomastoid ask the child to turn his head to one side or other against resistance

18. X11. HYPOGLOSSAL NERVE Ask the child to protrude the tongue ‐ it deviates to the paralyzed side Fasciculation of tongue in Wernig –Hoffman disease Atrophy of tongue on affected side in LMN palsy In UMN palsy ,tongue is spastic , thin and pointed

19. THANK YOU