Mitch Medical Healthcare

Cranial Nerve I Olfactory

The olfactory nerve supplies nerve endings to the superior nasal concha and upper one third of the nasal septum. The olfactory nerve is not routinely tested. However, in any patient with a suspected frontal lobe disorder, the olfactory nerve should be evaluated.

Table 21-1 Cranial Nerves Cranial Nerve

I: Olfactory

II: Optic

III: Oculomotor

IV: Trochlear V: Trigeminal

VI: Abducens VII: Facial

VIII: Vestibulocochlear

IX: Glossopharyngeal

X: Vagus

XI: Spinal accessory

Function

Smell

Vision

Eye movements; papillary constriction; accommodation

Eye movements

General sensation of face, scalp, and teeth; chewing movements

Eye movements

Taste; general sensation of palate and external ear; lacrimal gland and submandibular and sublingual gland secretion; facial expression

Hearing; equilibrium

Taste; general sensation of pharynx and ear; elevation of palate; parotid gland secretion

Taste; general sensation of pharynx, larynx, and ear; swallowing; phonation; parasympathetic innervation to heart and abdominal viscera

Phonation; head, neck, and shoulder movements

Clinical Findings with Lesion

Anosmia

Amaurosis

Diplopia; ptosis; mydriasis; loss of accommodation

Diplopia

''Numbness'' of face; weakness of jaw muscles

Diplopia

Loss of taste on anterior two thirds of tongue; dry mouth; loss of lacrimation; paralysis of facial muscles

Deafness; tinnitus; vertigo; nystagmus

Loss of taste on posterior one third of tongue; anesthesia of pharynx; partially dry mouth

Dysphagia; hoarseness; palatal paralysis

Hoarseness; weakness of head, neck, and shoulder muscles

XII: Hypoglossal

Tongue movements

Weakness and wasting of tongue