Cranial Nerves -- BDS

Question 1

CN I

Answer 1

olfactory nerve (smell)

sensory; special viceral afferent (SVA)

Only CN without thalamic relay to cortex!

Directly relay to piriform cortex

Question 2

CN II

Answer 2

Optic

• function = sight
• special somatic (voluntary) afferent (SSA)
• Lateral geniculate nucleus and pretectal nucleus (pupillary light reflex)

Question 3

CN III

Answer 3

Oculomotor

• Motor (general somatic efferent (GSE) and general visceral efferent-parasympathetic (GVE))
• function = eye movement (LR6SO4)R3 pupillary constriction (sphincter pupilae (EWN), muscarinic receptors), accomodation, eyelid opening (levator palprebrae)
• Nuclei: oculomotor nerve nucleus (superior collicullus of midbrain) + accessory Edinger-Westphal nucleus.

Question 4

CN IV

Answer 4

Trochlear

motor: general somatic efferent

one extraocular muscle– suberior oblique

nucleus: nucleus of the trochlear nerve in midbrain, immediately caudal to the oculomotor nucleus (superior colliculous)

Question 5

CN V

Answer 5

Trigeminal

• General somatic sensory and branchial somatic motor
• Both sensory and motor
• 4 nuclei: one motor (motor nucleus of trigeminal nerve) and three sensory (mesencaphalic, prinicipal sensory and spinal nuclei of trigeminal nerve)
• Function: mastication, facial sensation (ophthalmic, maxillary, mandibular), somatosensation from anterior 2/3 of tongue.

Question 6

CN VI

Answer 6

Abducens

• general somatic efferent (GSE)
• Function: eye movement to one muscle (lateral rectus)
• Nucleus: abducent nucleus in the pons near the median plane

Question 7

CN VII

Answer 7

Facial

• both sensory and motor
• special sensory (taste), general somatic sensory, branchial somatic motor and parasympathetic visceral motor
• facial movement, taste from anterior 2/3 of tongue, lacrmation, slaivation (submandibular and sublingual glands), eyelid closing (obicularis oculi), stapedius muscle in ear (note that nerve courses through parotid gland, but does not innervate it.

Question 8

CN VIII

Answer 8

Vestibulocochlear

• both sensory and motor
• special somatic afferent (special sensation of hearing, equilibrium, and motion (accelaration/deceleration)
• function: hearing and balance
• nucleus: vestibular nuclei (junction of pons and medulla), cochlear nuclei (medulla)

Question 9

CN IX

Answer 9

glossopharyngeal

• both sensory and motor
• general somatic sensory, special sensory (taste), visceral sensory, branchial somatic motor, and parasympathetic visceral motor
• 4 nuclei: Motor = nucleus ambiguus and inferior salivary nucleus; Sensory = snsory nuclei of the trigeminal nerve and nuclei of the solitary tract.
• function: taste and somatosensation from posterior 1/3 of tongue, swallowing, salivation (parotid gland), monitoring carotid body and sinus chemo- and baroreceptors, and stylopharyngeus (elevates pharynx, larynx).

Question 10

CN X

Answer 10

Vagus

• both motor and sensory
• general somatic sensory (GSS), special sensory (taste) (SST), visceral sensory, brachial somatic motor (BSM), parasympathetic visceral motor (PVM)
• Function: taste from epiglottic region, swallowing, soft palate elevation, midline uvula, talking, coughing, thoracoabdominal viscera, monitoring aortic arch chemo- and baroreceptors

Question 11

CN XI

Answer 11

accessory

• both sensory and motor
• gerneral somatic sensory (GSS), special sensory (taste) (SST), visceral sensory, brachial somatic motor (BSM), parasympathetic visceral motor (PVM)
• function: head turning, shoulder shrugging (SCM, trapezius)
• Nucleus: sensory nucleus of the trigeminal nerve and nuclei of the solitary tract (taste and viceral sensory), and dorsal vagal nucleus (PVM)

Question 12

CN XII