Cranial Nerves

Question 1

SSS

special sensory

Answer 1

special senses derived from ectoderm - sight sound and balance

Question 2

SVS

special visceral sensory

Answer 2

special senses derived from endoderm - taste

Question 3

SVM

special visceral motor

Answer 3

muscles derived from pharyngeal arches

Question 4

GVS

general visceral sensory

Answer 4

general sensation from viscera

Question 5

GVM

general visceral motor

Answer 5

to smooth muscles of gut tract and autonomic motor

Question 6

GSS

general somatic sensory

Answer 6

general senses from ectoderm (skin)

Question 7

GSM

general somatic motor

Answer 7

skeletal muscles

Question 8

CN I

Answer 8

• Olfactory Nerve
• SVS
• function: smell
• passes through cribiform plate to olfactory bulbs

Question 9

CN II

Answer 9

• Optic Nerve
• SVS
• function: sight
• exits through optic canal
• begins in ganglionic layer of retina

Question 10

CN III

Answer 10

• Oculomotor Nerve
• GSM and GVM
• superior orbital fissure
• GSM: oculomotor nuclear complex. supplies 4 of 6 extrinsic muscles of the eye (superior rectus, inferior rectus, medial rectus and inferior oblique) and levator palprae superioris
• GVM: Edinger-Westphal nucleus. supplies constrictor pupillae and ciliary muscles
• controls shape of lens and pupil

Question 11

CN IV

Answer 11

• Trochlear Nerve
• GSM
• superior orbital fissure
• function: eye movement
• innervates superior oblique muscle of eye
• only crossed cranial nerve
• only cranial nerve that emerges dorsally

Question 12

CN V

Answer 12

• Trigeminal Nerve
• major sensory nerve to face
• supplies motor innervation to muscles of mastication
• GSS: semilunar ganglion. sensory to face and anterior scalp, conjunctiva and eyeball, paranasal sinuses, nasal and oral cavities, anterior 2/3 tongue, external TM, dura of middle and anterior cranial fossa
• SVM: masticator nucleus. motor innervation to muscles of mastication )tempoalis, masseter and pterygoids), tensor veli palatini, tensor tympani, mylohyoid and anterior belly of digastric

Question 13

Ophthalmic Branch of Trigeminal Nerve

Answer 13

• superior orbital fissure
• general sensory to the orbit and its contents
• also sensation to nose, skin above eye (only upper eyelid)

Question 14

Maxillary Branch of Trigeminal Nerve

Answer 14

• foramen rotundum

- provides sensation to maxillary region

Question 15

Mandibular Branch of the Trigeminal Nerve

Answer 15

• foramen ovale

- provides sensation to the mandibular region

Question 16

CN VI

Answer 16

• Abducens Nerve
• superior orbital fissure
• function: eye movement
• GSM
• originates from abducens nucleus
• lies on medial aspect of lateral rectus muscle
• innervates lateral rectus muscle

Question 17

CN VII

Answer 17

• Facial Nerve
• stylomastoid foramen
• primary motor nerve to muscles of facial expression
• piggybacks on CN V to lacrimal gland
• SVM: supply mimetic muscles (temporal, zygomatic, buccal, mandibular, cervical), stapedius, stylohyoideus, and posterior digastric
• GSS: geniculate nucleus, supply external ear
• SVS: geniculate ganglion. taste from anterior 2/3 tongue, hard and soft palates
• GVM: superior salvitory nucleus and lacrimal nucleus. supplies lacrimal gland, submandibular and sublingual glands, and mucous glands

Question 18

CN VIII

Answer 18

• Vestibulocochlear Nerve
• leaves via internal acoustic meatus
• SSS
• auditory component: functions in hearing, cell bodies in spiral ganglion of cochlea
• vestibular component: functions in balance, cells bodies in vestibular ganglion

Question 19

CN IX

Answer 19

• Glossopharyngeal Nerve
• jugular foramen
• SVM: nucleus ambiguous, supplies the stylopharyngeus muscle
• GVM: parotid gland
• GVS: carotid body and carotid sinus
• GSS: sensation from posterior 1/3 of tongue, external ear, middle ear cavity
• SVS: taste from posterior 1/3 of tongue

Question 20

CN X

Answer 20

• Vagus Nerve
• motor innervation to muscles of larynx
• major parasympathetic nerve to thoracic and abdominal organs
• SVM: nucleus ambiguous. supplies striated muscles of pharynx and larynx (EXCEPT tensor veli palantini, stylopharyngeus and palatoglossal)
• GVM: myenteric plexus in wall of gut tube. supplies smooth muscles of pharynx, larynx, thoracic and abdominal viscera as far as left colic flexure
• GVS: sensation from larynx and pharynx, thoracic and abdominal viscera to left colic flexure
• GSS: sensation from external ear, pharynx

Question 21

CN XI

Answer 21

• Spinal Accessory Nerve
• enters through foramen magnum and exits through jugular foramen
• arises from C1-3 lateral rootlets
• SVM
• function: motor innervation to sternocleidomastoid and trapezius

Question 22

CN XII

Answer 22

• Hypoglossal Nerve
• hypoglossal foramen
• GSM
• supplies extrinsic and intrinsic muscles of tongue
• descends in neck b/w internal carotid and internal jugular
• in neck gives rise to superior root of ansa cervicalis and nerve to thyrohyoid muscle