Cranial Nerves I, II, III, IV, VI PDF

CN I OLFACTORY NERVE  CN I Olfactory Nerve Origin/Course – odor molecules – nerve endings are triggered – nerve impulse sent – olfactory bulb  CN I Olfactory Nerve Termination – olfactory cortex (inferior/medial temporal lobe) Function – olfactory signal is...

CN I OLFACTORY NERVE  CN I Olfactory Nerve Origin/Course – odor molecules – nerve endings are triggered – nerve impulse sent – olfactory bulb  CN I Olfactory Nerve Termination – olfactory cortex (inferior/medial temporal lobe) Function – olfactory signal is processed and interpreted (noxious smell; pleasant smell)  CN I Olfactory Nerve Clinical Concerns anosmia – lack of smell hyposmia – decreased sense of smell hyperosmia – hypersensitive smell individuals with TBI will have smell complaints because damage at base of skull results in damage to CN I tract CN II OPTIC NERVE  CN II Optic Nerve Origin/Course – light – eye - retina  CN II Optic Nerve Origin/Course – retina structure lines the posterior part of the eye photoreceptor layer where light energy Is transduced into electrical signals  CN II Optic Nerve Origin/Course – optic nerve – optic chiasm cross over structure between the optic nerves and the optic tract CN II Optic Nerve  CN II Optic Nerve Course – LGN (thalamus) – geniculocalcarine tract (optic radiations) Termination – occipital lobe Function – vision  CN II Optic Nerve Clinical Concerns visual field cuts – loss of vision in one of four visual fields/quadrants – individuals with aphasia or TBI can have visual field cuts because of damage to the optic radiations CN III, IV, VI  CN III Occulomotor Nerve Origin/Course – oculomotor nucleus  CN III Occulomotor Nerve Origin/Course – fibers travel ventrally through brainstem to arrive at eyes Termination – various eye muscles Function – eye movements  CN III Occulomotor Nerve Origin/Course – Edigner-Westphal nucleus – fibers course ventrally through the midbrain with the fibers of occulomotor nucleus  CN III Occulomotor Nerve Termination – pupillary sphincter (eye muscle) Function – pupillary light reflex reflexive dilation of the pupil to control amount of light entering the eye  CN III Occulomotor Nerve Termination – ciliary muscle Function – accommodation reflex reflexive changes in the shape of lens for near vision and when eyes need to converge onto an object  CN IV Trochlear Nerve Origin/Course – trochlear nucleus – fibers travel posteriorly to exit at level of inferior colliculus – fibers then travel ventrally to the single eye muscle it innervates  CN IV Trochlear Nerve Termination – eye muscle Function – eye movement  CN IV Trochlear Nerve Claim to Fame – only cranial nerve to exit brain dorsally – only cranial nerve that exists in a completely crossed fashion  CN VI Abducens Nerve Origin/Course – abducens nucleus – fibers travel ventrally through brainstem to arrive at eyes  CN VI Abducens Nerve Termination – eye muscles Function – eye movement