Neurological examinations Examination of the Cranial nerves Enas Sabah MSc. Human Physiology

Cranial nerves Are a set of 12 paired nerves that arise directly from the brain & divide into sensory motor and mixed nerves. The olfactory and optic nerves arise from the cerebellum while the remaining emerge from brain stem

Examination of the Cranial nerves: 1. Olfactory n. this nerve is examined by giving the patient different types of odors like fruit and peppermint. 2. Optic n. : the following tests are done: Visual acuity (Snellen`s chart) Visual field Color vision (Ishihara`s chart)

3. Oculomotor, 4. Trochlear, 6. Abducent nerves: These nerves supply the extraocular muscles. To test them, move your finger in front of the patient's eye in different directions and ask him to follow your finger.

5.Trigeminal n.: it has motor and sensory parts: Motor: put hands on temporal and masseter muscles with the patient clenching his teeth. Sensory: test the sensation over the areas of face supplied by the 3 branches of trigeminal n., Corneal reflex: touching the cornea with a piece of cotton will lead to blinking.

7. Facial n.: Motor: a. Try to open the patient’s eyes while he attempts to keep them closed. b. Ask the patient to whistle. c. Ask him to smile. d. Ask him to fill his mouth and blow out his cheek. Sensory: Taste function: feel the taste over anterior two/third of the tongue.

8.Vestibulocochlear n.: Vestibular branch: rotate the patient while sitting on a chair and observe presence of nystagmus. Other tests also can be done.

Cochlear branch: two tests are done: Rinne test a vibrating tuning fork is first placed over the mastoid process. When the sound is no longer perceived, the fork is immediately placed in front of the ear. For normal hearing the fork should be heard for twice as long when it is at the air as when it is vibrating on the mastoid process. In conductive deafness, the vibration is heard only or predominately through the mastoid process indicating that air conduction is impaired.

2. Weber test: a vibrating tuning fork is placed on the middle of the forehead. Normally the sound is heard equally at both sides. In conductive deafness, the sound is heard well on impaired side, whereas with perceptive deafness the normal ear hears the sound better.

9. Glossopharyngeal n.: it is examined by feeling the taste over posterior one/third of tongue. Also it mediate the sensory part of gag reflex (It is done by touching the uvula which induces nausea).

10. Vagus n.: 1. Look at soft palate movement by asking the patient to say aahh. 2. Gag reflex (motor part) 3. Swallowing 4. Voice production.

11. Accessory n. Ask the patient to shrug his shoulders while you press on them downwards. Also ask him to rotate his chin while you apply resistance against the chin and watch the contraction of sternomastiod muscle. 12. Hypoglossal n.: ask the patient to bring out his tongue and move it in different directions.