The Cranial Nerves

• I - Olfactory nerve
• II - Optic nerve
• III - Oculomotor nerve
• IV - Trochlear nerve
• V - Trigeminal nerve
• VI - Abducens nerve
• VII - Facial nerve
• VIII - Vestibulocochlear nerve/Auditory nerve
• IX - Glossopharyngeal nerve
• X - Vagus nerve
• XI - Accessory nerve/Spinal accessory nerve
• XII - Hypoglossal nerve

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• brainstem
• diencephalon
• midbrain
• pons medulla

• in the motor cortex and transmit impulses from brain to tissue outside brain (corticobulbar tract is a collection of UMN axons and controls head/neck)
• in ganglia outside brain and transmit impulses from sensory organs to brain

• smell receptors stimulated
• action potential initiated in nasal mucosa
• olfactory bulb gathers info
• sends to other structures of CNS via olfactory tract

(Anosmia)

• carries info from retina past optic chiasm 
• to the optic tract, which reaches the occipital lobe via the 
• thalamus

damage is predictable given location of damage

• Motor to eyelid and extrinsic eye muscles
• sensory from these muscles to brain
• facilitates pupil dilation and movement of some eye muscles

Damage can result in ptosis

• Motor to eye muscles (allows up and out movement of the eye)
• Sensory from these muscles

Damage can result in diplopia

• motor innervates muscles of mastication (Masseter, Digastric)
• sensory from face, scalp, nose, and mouth (3 divisions)

• Unilateral damage to LMN: ipsilateral jaw deviation 
• Unilateral UMN lesion: no significant effect
• Bilateral UMN lesion: significant limitations in jaw movement
• Doctor can test for positive jaw jerk

• motor to lateral rectus 
• sensory from this muscle to brain

Damage: failure of lateral rectus to abduct (can't look to the side)

(temporal, zygomatic, buccal, mandibular, cervical)

Motor to all muscles of facial expression, lower face has unilateral innervation, upper face has bilateral innervation

Sensory from anterior 2/3rds of tongue and proprioceptive fibers from facial muscles

• sensory from vestibular apparatus and semicircular canals about equilibrium
• sensory from organ of corti/cochlea about hearing

Damage results in hearing impairment or vertigo

• motor to pharyngeal muscle for swallowing and parasympathetic fibers to salivary glands
• Sensory from pharynx, tonsils, posterior 1/3rd of tongue

Damage: swallowing/numbness of ipsilateral pharynx

• Motor to pharynx, larynx, heart, and other organs
• sensory from neck, chest, and abdomen 

Unilateral damage to lower motor lesion: affects larynx, hoarseness, difficulty swallowing

• Motor stimulation to sternocleidomastoid and trapezius muscles via spinal fibers
• Motor from medulla innervate soft palate, pharynx, and larynx (cranial root) 
• Sensory from the above mentioned 

Damage: drooping shoulder, trouble turning head towards lesion