Cranial Nerves Flashcards
describe directional terminology for the forebrain
- rostral - anterior
- dorsal - superior
- caudal - posterior
- ventral - inferior
describe directional terminology for the brainstem and spinal cord
- rostral - superior
- caudal - inferior
- ventral - anterior
- dorsal - posterior
names of cranial nerves I-XII
- CN I - olfactory n.
- CN II - optic n.
- CN III - oculomotor n.
- CN IV - trochlear n.
- CN V - trigeminal n.
- CN VI - abducens n.
- CN VII - facial n.
- CN VIII - vestibulocochlear n.
- CN IX - glossopharyngeal n.
- CN X - vagus n.
- CN XI - accessory n.
- CN XII - hypoglossal n.
describe general somatic afferents of cranial nerves
- somatic sensation
- fibers convey impulses from the skin and striated muscle spindles
describe general visceral afferents of cranial nerves
- visceral sensation
- fibers convey impulses from the viscera and blood vessels
describe general visceral efferents of cranial nerves
- visceromotor function
- fibers innervate the smooth muscle of the viscera, intraocular muscles, heart, salivary glands, etc.
describe general somatic efferents of cranial nerves
- somatomotor function
- fibers innervate striated muscles
describe special somatic afferents of cranial nerves
- fibers conduct impulses from the retina and from the auditory and vestibular apparatus
describe special visceral afferents of cranial nerves
- fibers conduct impulses from the taste buds of the tongue and from the olfactory mucosa
describe special visceral efferents of cranial nerves
- fibers innervate striated muscles derived from the branchial arches (branchiogenic efferents and branchiogenic muscles)
describe CN I
- olfactory n.
- special sensory
- only sensory
- part of the telencephalon, NOT a true cranial nerve
- true olfactory fibers run from olfactory epithelium in the nasal cavity through cribriform plate and innervate the olfactory bulb
describe CN II
- optic nerve
- special sensory
- only sensory
- part of the diencephalon, NOT a true cranial n.
- some fibers cross, others do not, at the optic chiasm
- fibers then run in the optic tract
- leaves the orbit via the optic canal
describe CN III
- oculomotor nerve
- somatic motor control - superior rectus m., inferior rectus m., medial rectus m., and inferior oblique m.
- upper eyelid - levator palpebrae superioris
- visceral motor control - pupillary constrictors, pupillary sphincter, ciliary muscle
- enters orbit via superior orbital fissure
describe CN IV
- trochlear n.
- somatic motor control - superior oblique
- enters orbit via superior orbital fissure
- only CN with contralateral symptoms in nuclear lesion (still ipsilateral in nerve lesion)
- only CN to emerge from dorsal surface
describe CN VI
- abducens n.
- somatic motor control - lateral rectus m.
- pulls the eye away from the midline (abduction of the eye)
which 3 cranial nerves control ocular muscles?
- CN III, IV, and VI
describe CN V
- trigeminal n.
- emerges in the middle of the pons
- trigemical ganglion
- 3 branches: V1 - ophthalmic, V2 - maxillary, V3 - mandibular
- innervates: muscles of mastication, oral floor muscles, tensor tympani (middle ear), tensor veli palatini (pharyngeal)
- sensation of the face, forehead, and tongue
- branches of other cranial nerves join up with CN V
describe the general sensory innervation of CN V
- ophthalmic division (V1)
- trigeminal ganglion
- maxillary division (V2)
- mandibular division (V3)
- skin of the face, nasal mucosa, and anterior 2/3 of the tongue
describe the general motor innervation of CN V
muscles of mastication:
- temporalis
- maseter
- medial pterygoid
- lateral pterygoid
describe the visceral hitchhikers of CN V
- branches of CN VII hitchhike on V2 and V3 nerves to get to glands in the face
- branch of CN IX hitchhikes on V3 / posterior auricular to get to parotid gland
describe ophthalmic division of CN V
- V1
- exits through the superior orbital fissure
- frontal n.
- nasociliary n.
- lacrimal n. (sensory only)
describe the maxillary division of CN V
- V2
- exits via the foramen rotundum
- posterior, middle, anterior superior alveolar nn.
- infraorbital n.
- zygomatic n.
describe the mandibular division of CN V
- V3
- exits via the foramen ovale
- auriculotemporal n.
- buccal n.
- pterygoid branch
- masseteric branch
- inferior alveolar n.
- lingual n.
which 3 nerves penetrate the foramen ovale?
- auriculotemporal n.
- inferior alveolar n.
- lingual n.
what are the features of the lingual n.?
- runs medial to the mandible
- branch of V3
- general sensory - mucosa, 2/3 of tongue, and floor of mouth
- chorda tympani
describe the chorda tympani
- branch of CN VII
- runs with lingual n.
- innervates glands (submandibular, sublingual, sm ones)
- taste, anterior 2/3 of tongue
what are the features of the inferior alveolar n.?
- part of the mandibular division (V3) of CN V
- runs within the mandible, enters mandibular foramen
- mylohyoid, anterior belly of digastric (motor)
- pulp of teeth (sensory)
- mental n. - skin and lip (sensory)
what are the 5 branches of CN VII that innervates muscles of facial expression?
- temporal
- zygomatic
- buccal
- cervical
- posterior auricular
what is the greater petrosal n.?
- branch of CN VII that innervates lacrimal and nasal glands
what is the nerve to stapedius?
- branch of CN VII that innervates the stapedius m.
- branches that innervate stylohyoid and posterior belly of digastric
describe CN VIII
- vestibulocochlear n.
- special sensory n. only, but 2 different modalities: vestibular senses and sense of hearing
describe CN IX
- glossopharyngeal n.
- exits via jugular foramen
describe the motor innervation of CN IX
- pharyngeal constrictors
- stylopharyngeus
- parotid gland
describe the sensory innervation of CN IX
- posterior tongue
- posterior oral pharynx
- mucosa - middle ear
- skin - external ear, canal
- tympanic membrane
describe the special sensory innervatino of CN IX
- taste - posterior 1/3 tongue
- chemoreceptors and baroreceptors - carotid sinus
describe the sensory innervation of CN X
vagus n.
- visceral in abdomen and thorax
- laryngopharynx and larynx
- taste - epiglottis
- ear and external acoustic meatus
- posterior cranial fossa - dura
describe the motor innervation of CN X
vagus n.
- pharyngeal constrictors (with CN IX)
- laryngeal mm.
describe the special sensory innervation of CN X
vagus n.
- pressure receptors - aortic arch
- chemoreceptors - aortic body
describe CN XI
- spinal accessory n.
- innervates SCM and trapezius mm
- ascends cord, into skull via foramen magnum, exits with CN X via jugular foramen
what motor deficits are associated with CN XI impingement?
- will not be able to contract muscles (trapezius and SCM)
describe CN XII
- hypoglossal n.
- motor only
- tongue muscles
- exits via hypoglossal canal
which cranial nerves are motor only?
- CN III - oculomotor n
- CN IV - trochlear n.
- CN VI - abducens n.
- CN XI - accessory n.
- CN XII - hypoglossal n.
which cranial nerves are sensory only?
- CN I - olfactory n.
- CN II - optic n.
- CN VIII - vestibulocochlear
which cranial nerves are both sensory AND motor?
- CN V - trigeminal n.
- CN VII - facial n.
- CN IX - glossopharyngeal n.
- CN X - vagus n.
describe the relationship between location (dorsal/ventral) of cranial nerves and their modality (sensory vs. motor)
- more dorsal (lateral) nerves are sensory
- more ventral (medial) nerves are motor
