cranial nerves Flashcards
what are cranial nerves
12 pairs of nerves that emanate from the base of the brain, numbered rostral to caudal
function of cranial nerves
cranial nerves provide motor and sensory innervation of the head and neck, they provide innervation of special sense organs(5 senses) and carry sympathetic and parasympathetic fibers of the ANS to structures in head neck thorax and abdomen
cranial nerves that are sensory, motor, both, and ones that contain visceral motor (autonomic) function
sensory: i, ii, viii
motor: iii, iv, vi, xi, xii
both: v, vii, ix, x
Visceral motor autonomic: 3 7 9 10
some say marry money, but my brother says big breasts matter more
Olfactory nerves (CN I)
cranial exit: cribriform plate
cell bodies: nasal mucosa (olfactory epithelium)
Components: Special visceral afferent
chief function: Smell
Lesion of olfactory could be due to ethmoid bone fracture-> anosmia no smell sometimes they wont taste
Optic nerves (CN II)
cranial exit: Sphenoid bone- optic canal
cell bodies: ganglion of retina
Components: special somatic afferent
chief function: Special Sensory- vision
lesion of optic nerves causes issues of vision due to eyeball energy
Oculomotor (CN III)
- function: somatic motor eye movement and visceral motor nerves
- location of neuron cell bodies: upper midbrain- oculomotor nucles
- passage thru skull: sphenoid bone-superior orbital fissure
- Route: superior orbital fissure- then splits and one branch goes to somatic motor muscles and one branch goes to ciliary ganglion which inervates visceral motor nerves (pupillary sphincter and ciliary muscle
- Structures innervated: levator palp m., SR m, IR m, MR, IO (LR6, SO4)everything else 3
- Injury and explanation: complete oculomotor nerve palsy is associated with: ptosis (droopy eyelid), down and out eyeball (SO and LR unopposed), a pupil thats fixed and dialated
- Causes of injury: Cavernous sinus injury or anuerysms of posterior cerebral or superior cerebellar arteried
Trochlear (CN IV)
*cranial exit: sphenoid bone-Superior Orbital Fissure
*location of neuron cell bodies: lower midbrain-trochlear nucleus
*chief function: somatic motor- eye movements
Route: midbrain to cavernous sinus to superior orbital fissure to outside of common tendinous ring (where all eye muscles come out) to superior oblique m.
lesion-> paralysis of superior oblique muscle of the eye causing diplopia (Double vision when looking down, headaches) cant look down when eye is abducted, due to cavernous sinus injury
Abducens (CN VI)
- cranial exit: sphenoid bone-Superior orbital fissure
- loc of neuron cell bodies: Pons-abducent nucleus
- chief function: eye movement lateral rectus m.
- route: cavernous sinus to superior orbital fissure to inside of common tendinous ring
*injury: horizontal diplopia, cant abduct eye, eye will be (medial unoppsed medial rectus). due to cavernous sinus injury or fracture of base of skull
Vestibulocochlear (CNVIII)
cranial exit: temporal-internal acoustic meatus
location of neuron cell bodies: spiral ganglia (cochlea) and Vestibular ganglion
chief function: special sensory hearing and balance
lesion causes vertigo and tinnitus (ringing and buzzing) could be due to tumor
Accessory (CN XI)
- cranial exit: occipital bone- rootlets go into foramen magnum and then comes out of jugular foramen
- chief function: SCM m., and trapezius head and neck movement
- location of neuron cell bodies: spinal cord-anterior horn of cervical region
*lesion- weakness in turning head to opposite side (SCM) and or weakness of shrugging shoulders (trap) due to neck laceration
hypoglossal (CN XII)
- cranial exit: Hypoglossal canal
- loc of neuron cell bodies: medulla hypoglossal nucleus
- chief function: somatic motor for tongue
- route: medulla to hypoglossal canal and goes above ansa cervicalis to go into tongue
- lesion: peripheral lesion causes tongue to deviate toward side of injury due to neck laceration
special sensory cranial nerves
I-smell
II-vision
VII, IX, X- taste
VIII- hearing and balance
somatic sensory cranial nerves
for information relay for body position (proprioception), pain, temp, vibration, and touch
CN V, VII, IX, X
visceral sensory cranial nerves
sensory info from viscera except pain
CN IX, X
Visceral Motor cranial nerves
this is autonomic innervation of cardiac muscle, smooth muscle, and glands
CN III, VII, IX, X
Branchial motor cranial nerves
innervation of muscle thats derived from branchial arches
CN V, VII, IX, X, XI
Somatic motor cranial nerves
innervation of muscle from myotomes
CN III, IV, VI, XII
trigeminal CN V (Ophthalmic V1)
- function: purely somatic sensory, from skin of forhead, scalp, mucous membranes (nasal)
- loc of neuron cell bodies: trigeminal semilunar ganglion
- route:sphenoid bone- superior orbital fissure
- injury: anesthesia numbness due to inflammation
trigeminal CN V (Maxillary V2)
- function: purely somatic sensory, from skin of upper lip, skin over prominence of cheek, palate, maxillary sinus
- loc of neuron cell bodies: trigeminal semilunar ganglion
- route:trigeminal semilunar ganglion to foramen rotundum
- injury:anesthesia, trigeminal neuralgia/Tic douloureux (intermittent excruciating pain) due to inflammation
trigeminal CN V
(mandibular V3)
sensory division
- function: somatic sensory-sensory from skin of lower jar, from mucosa on anterior 2/3 tongue
- location of cell bodies: trigeminal seminlur ganglion
- route: sphenoid bone-foramen ovale
- injury: anesthesia due to inflammation
trigeminal CN V
(mandibular V3)
motor division
- function: branchial motor- chewing and swallowing
- loc of neuron cell bod- Pons motor nuc of V
- route: to foramen ovale
- structures inn: muscles of mastication (temporalis, lat+med pterygoids, masseter), tensor veli palatini, tensor tympani, mylohyoid, ant. digstric
*injury: difficulty chewing due to inflammation
Facial nerve CN VII (somatic sensory division)
- function- sensory from skin behind, enternal acoustic meatus, tympanic membrane (external surface)
- loc of neuron cell bodies: geniculate ganglion
- route: geniculate ganglion to internal acoustic meatus then leaves stylomastoid foramen
- injury: anesthesia
Facial nerve CN VII (special sensory division)
- function: taste from tongue (anterior 2/3rds) and taste from palate
- loc of neuron cell bodies: geniculate ganglion
- Route: enters internal acoustic meatus leaves thru petrotympanic fissure
- injury: cant taste due to chorda tympani nerve damage
Facial nerve CN VII (motor division)
- function: facial expression
- loc of neuron cell bodies: motor nucleus of VII
- route: enter internal acoustic meatus leaves stylomastoid foramen
- route: TZBMC branches
- inn: muscles of facial expression (platysma, buccinator, frontalis, occipitalis, orbicularis oculi, orbicularis oris) stapedius, stylohyoid, posterior digastric
- injury: Bells palsy (facial paralysis, eyelids dont close, angle of mouth droops, fore head droops) due to parotid gland innervation distal to stylomastoid foramen
