Neuroscience Section 2 PDF

Neuroscience Section 2 Cranial nerves Olfactory nerve (CN I) optic nerve (CN II) oculomotor nerve (CN III) trochlear nerve (CN IV) trigeminal nerve (CN V) abducens nerve (CN VI) facial nerve (CN VII) vestibulocochlear nerve (CN VIII) glossopharyngeal nerve (CN IX) vagus nerve (CN X) accessory nerve...

Neuroscience Section 2 Cranial nerves Olfactory nerve (CN I) optic nerve (CN II) oculomotor nerve (CN III) trochlear nerve (CN IV) trigeminal nerve (CN V) abducens nerve (CN VI) facial nerve (CN VII) vestibulocochlear nerve (CN VIII) glossopharyngeal nerve (CN IX) vagus nerve (CN X) accessory nerve (CN XI) hypoglossal nerve (CN XII ) I-Olfactory nerve Function: smell Ty pe: sensory (special senses) Lesion: Anosmia- loss of sense of smell. Hyposmia- decrease ability to detect smell. Hyperosmia- increased sensitivity to the sense of smell. Parosmia: distorted odor perception Phantosmia: olfactory hallucination Olfactory nerve examination Testing of the integrity of the olfactory nerve involves blocking of one nostril while the patient is blindfolded or with the eyes closed, then have the patient smell aromatic substances such as coffee, vanilla, cinnamon, etc. Avoid using substances with strong or noxious smell such as alcohol or ammonia. Have the patient identify the substance based on its aroma. Then repeat the same procedure on the other nostril. This is done to compare the sense of smell on both sides. II-Optic nerve Optic nerve Function: vision Type: sensory (special senses) Lesion: 1- Monocular blindness: loss of vision in one of your eyes 2- Bitemporal hemianopia : partial blindness in which vision is impaired in the outer half of both the right and left visual fields. 3- Homonymous hemianopia: a field loss deficit in the same halves of the visual field of each eye Optic nerve examination Visual Acuity Test Snellen chart Visual Field Test Confrontation test Visual Reflexes Test Pupillary light reaction (cranial nerves II & III) III-Oculomotor nerve Function: eye movement Ty pe: motor (somatic to 4 extraocular muscles and autonomic fibers to the pupil and ciliary muscle of lens) Lesion: Ptosis: (droopy eyelid) due to paralysis of levator palpebrae superioris Down and out positioning of the affected eye Dilated pupil (mydriasis) : caused by lack of parasympathetic innervation IV-Trochlear nerve Function: eye movement Type: motor (supplies superior oblique muscle) Lesion: Verhical Diplopia: when the patient looks downward Weakness in depression of adducted eye VI-abducens nerve Function: eye movement Type: motor (supplies lateral rectus muscle) Lesion: Horizontal Diplopia Abductor paralysis Oculomotor, Trochlear and Abducens nerves examination V-Trigeminal nerve Function: face sensation + muscles of mastication (masseter, temporal, and pterygoid muscles) Type: mixed Lesion: Loss of facial sensation Absent corneal reflex Exaggerated Jaw reflex in UMNL Weakness of mastication muscles Trigeminal nerve examination Sensory examination Using a cotton wisp, where the examiner gives instructions to the patient to close their eyes and say "yes" each time they feel a touch. For testing nociception, the same procedure is followed as above, but this time the testing object is a sharp object rather than a cotton wisp. Trigeminal nerve examination Motor examination The subject is asked to clench their teeth, while the examiner palpates the temporalis and the masseter muscle to assess its muscle tone. Muscle strength - can be assessed by placing the fingers of the examining hand beneath the chin and asking the patient to open the mouth and resist closure. Trigeminal nerve examination Reflex examination Corneal reflex: involves B/L involuntary blinking of the eyelids stimulated by thermal, painful or tactile stimulation of the cornea. The absence of this reflex is indicative of TNr/Ophthalmic nerve or facial nerve damage as the ophthalmic nerve is the afferent limb and the facial nerve is the efferent limb. Trigeminal nerve examination Reflex examination Jaw reflex: The mandible “or lower jaw” is tapped at a downward angle just below the lips at the chin while the mouth is held slightly open. In response, the masseter muscles will jerk the mandible upwards. Normally this reflex is absent or very slight. However, in individuals with upper motor neuron lesions the jaw jerk reflex can be quite pronounced. (VII )FACIAL NERVE: Type: It is mixed nerve. Function: a-Moto r part: It supplies muscles of the face, posterio r belly of digastric, stylohyo id, stapediu s b-Sensory part receiv es taste (special) sensation from the anterio r 2/3 of the tongue and the buccal cavity. c-Autono mic (parasymp ath etic) part supplies submand ibu lar gland, sublingual gland, lacrim al glands lesion How differentiate clinically between UMN and LMN Facial paralysis. 1. By asking the patient to close eye on the affected side. If he can then it is UMNL. If he can’t, then it is LMNL. 2. Saying joke. If the patient laughs and improve asymmetry then it is UMNL. If not, then it is LMNL Examination A- MOTOR PART Examination (VIII )VESTIBULOCOCHLEAR Type :-It is purely sensory. Function and lesion:- It divides into two parts:Cochlear part :- It carries impulses for hearing and its lesion leads to decrease acuity of hearing and tinnitus. Vestibular part: - It carries impulses for equilibrium ( head position and movement) and its lesion leads to vertigo. Examination 1- Rinne Test 2- Weber Test IX- GLOSSOPHARYNGEAL NERVE Type: It is mixed nerve. Function:- 1-Motor fibers to the Stylopharyngeus muscle which play role in swallowing and speech - Constrictors of the pharynx. 2- Sensory fibers: -General sensation from the posterior 1/3 of tongue, -Taste sensation from the posterior 1/3 of tongue. 3- Autonomic fibers (Parasympathetic fibers) to the parotid gland. Lesion Loss of taste from posterior 1/3 of tongue Decreased sensation on the back of tongue Diminished gag reflex Trouble swallowing X- VAGUS NERVES Type: It is mixed nerve. Function:1-Motor fibres: to the soft palate, pharynx and larynx. 2- Sensory fibers from: -Throat and outer part of the ear -Internal organs (The thoracic and abdominal viscera) 3- Autonomic fibres: - Parasympathetic fibres to the heart (inhibitory) and the GIT Lesion Diminished gag reflex Trouble swallowing Hoarseness of voice Abnormalities in heart rate GIT problems Examination of GLOSSOPHARYNGEA and VAGUS NERVES XI- ACCESSORY NERVE: Type: It is purely motor nerve. Function:Cranial part: It shares in the motor innervations of the soft palate and pharynx. (As vagus nerve) Spinal part: It supplies the sternomastoid and trapezius muscles. Examination XII-HYPOGLOSSAL NERVE Type: It is purely motor nerve.. Function: It supplies the intrinsic and extrinsic muscles of the tongue. Lesion:tongue weakness or atrophy Problems with speech and swallowing ( if both nerves are damaged ) Examination Thank you