GA: Cranial Nerves Flashcards
Which cranial nerves are special sensory?
1, 2, 8
Which cranial nerves are motor?
3,4,6,11,12
Which cranial nerves are mixed? (motor + sensory)
5, 7, 9, 10
What cranial nerves are GSE? (General Somatic Efferent): Somatic Muscle
3,4,6,12 (motor to muscle)
Which cranial nerves are GVE (general visceral efferent): autonomics to smooth and cardiac muscle + glands??
Parasympathetic:
3,7,9,10
Which cranial nerves are SVE (Branchial or Special Visceral Efferent): muscles dervied from the pharyngeal arches?
5 - arch 1
7 - arch 2
9 - arch 3
10 - arches 4 + 6
What does general somatic afferent (GSA) mean?
Sensory in the skin, joint capsule, tendon, muscle
Ectoderm (outside)
Ex. “I have a cut right here”
What does GVA (general visceral afferent) mean?
Sensory of visceral structures
Endoderm (inside)
Which cranial nerves are SSA (special somatic afferents)?
hearing + balance = 8
sight = 2
Which cranial nerves are SVA (special visceral afferent)?
chemical senses
taste = 7,9,10
smell = 1
What is the function + location of the olfactory N. (I)?
Function: (SVA) Special sense of smell
Location: Olfactory organ
What is the tract of the olfactory N.?
Cribriform plate –> olfactory bulbs
How do you examine for CN 1?
Test w/ several different familiar odors
What are some clinical problems associated with the olfactory N.?
Ansomia - Olfactory loss (loss of smell)
CSF Rhinorrhea (CSF leakage through nose)
Smell gradually decreases w/ age –> less taste
What is the function of the optic nerve?
SSA: special sense of vision
What is the optic N. tract?
Ganglion cells in retina –> optic nerve –> exit orbit via optic canal –> middle cranial fossa –> lateral geniculate bodies of thalamus
How do you examine the optic nerve?
Graded testing of visual acuity: light + dark, finger counting, snellen’s eye chart, visual field, peripheral vision
Pupillary light reflex (pen light) (nerves 2 + 3)
Blink Reflex (nerves 2 + 7)
What structures is right next to the optic chiasm and what can happen clinically if this structure enlarges?
Pituitary gland = right next to optic chiasm
If you have a pituitary tumor this can cause bitemporal hemianopia (loss of vision laterally in both eyes).
What is the function of the oculomotor N. (CN III)?
GSE: Motor innervation to superior, medial, and inferior recti + inferior oblique and levator palpebre superioris
GVE: Parasympathetic innervation to pupil + ciliary muscle
What is the tract for the oculomotor N.?
midbrain –> dura @ cavernous sinus –> superior orbital fissure
What is the function of the trochlear n.?
(GSE): Motor innervation to superior oblique
Exits dorsal (only N. to exit dorsally) surface of midbrain –> superior orbital fissure
What is the function of abducens (CN VI)?
GSE: motor innervation to lateral rectus
What is the tract for abducens?
Brainstem –> pontine cistern –> cavernous sinus –> superior orbital fissure
Which nerves control the motor innervation of the eye?
3 - intra ocular + four extra ocular M.’s
4 - superior oblique
6 - lateral rectus
How do you examine nerves 3,4, and 6?
Oculomotor: Pupillary light reflex, accomodation, extraocular muscle (EMO) testing (H finger)
Trochlear: SO - adduct eye, then look down
Abducens: LR - abduct eye
Which nerves would a cavernous sinus thrombosis or an aneurysm affect?
3,4,6
What is the function of trigeminal (CN V)?
SVE: V3 - Motor innervation to muscles of mastication (muscles for chewing)
GSA: Sensory to face + scalp (via V1,2,3)
What is the tract of CN V + all its parts?
Pons –> cavernous sinus –>
V1 Opthalmic = Superior Orbital Fissure
V2 Maxillary = Foramen Rotundum
V3 Mandibular = Foramen Ovale
How do you examine for CN V?
Opthalmic Division: Senstion - of forehead + nose, corneal reflex (touch cornea w/ cotton)
Maxillary Division: Sensation - cheek
Mandibular Division: Sensation - chin + motor - muscles of mastication (chewing)
What are some clinical problems that can go wrong with the trigeminal nerve?
Trigeminal Neuralgia: Trigeminal neuralgia is a chronic pain condition that affects the trigeminal nerve, which carries sensation from your face to your brain. If you have trigeminal neuralgia, even mild stimulation of your face — such as from brushing your teeth or putting on makeup — may trigger a jolt of excruciating pain.
What are the functions of the facial N.?
SVE: Motor innervation to muscles of facial expression (pharyngeal arch 2)
GVE: Parasympathetic innervation to lacrimal, nasal, palatine, and submandibular + sublingual salivary glands
SVA: Taste to anterior 2/3 of tongue
GSA: Sensation to external acoustic meatus
What is the tract of the facial N.?
Emerges from pontine-medullary junction –> exits skull via internal acoustic meatus –> runs in facial canal –> exits via stylomastoid foramen –> pass through parotid gland
What is the tract for how the facial nerve sends parasympathetics to the lacrimal gland?
What is the tract for how the facial nerve sends parasympathetics to the salivary (submandibular + sublingual glands)?
How do you examine the facial N.?
Sensation - taste anteror 2/3 of tongue
Motor - upper division: wrinkle forehead or close eyes
lower division: blow, whistle, smile
Blink reflex - optic + facial
Corneal reflex - V1 + facial
What disorder is caused by a lesion of the facial N.?
Bell’s Palsy
What is the function of the vestibulocochlear N.?
SSA: Special sense of hearing + equilibrium
What is the tract for CN 8?
Vestibular N. innervates utricle + sacule
Cochlear N. innervates cochlea
Enter skull via internal acoustic meatus
Enter brainstem on pontine-medullary junction
How do you test the vestibulocochlear N.?
Vestibular Division:
Romberg’s sign (balance w/ feet togethe + eyes closed)
Past Pointing (finger to nose)
Nystagmus (abnormal eye movement)
Cochlear Division:
Check for conduction deafness (impacted wax, torn tympanic mem., etc) by whispering or rubbing fingers together)
Rinne test: tunning fork on pinna (normal = AC > BC)
Weber’s Test: (confirm) tunning fork on top of head and sound lateralizes to bad ear
What are the clinical correlations with CN 8?
Tinnitus (ringing of ears)
Balance Disturbance (vertigo)
Nystagmus (eye jumping)
Deafness (completely cut nerve)
Acoustic neuroma (benign tumor on CN 8)
What is the function of the glossopharyngeal N (CN IX)?
GSA: Sensation from ear + external auditory canal + posterior 1/3 of tongue
GVA: Sensory information from oropharynx and carotid body
SVA: taste to posterior 1/3 of tongue
GVE: Parasympathetics to parotid gland
SVE: motor to stylopharyngeus muscle
What is the tract for CN 9?
Medulla –> jugular foramen –> passes between superior + middle pharyngeal constrictors –> enters oral cavity
How do you test CN 9?
*9 + 10 tested together*
Sensory = taste on back 1/3 of tongue
- gag reflex
What is a clinical correlation of glossopharyngeal neuralgia?
Glossopharyngeal neuralgia is extreme pain in the back of the throat, tongue or ear. Attacks of intense, electric shock-like pain can occur without warning or can be triggered by swallowing.
What is the function of the vagus CN 10?
GSA: Sensation from external auditory canal + dura
GVA: Sensory information from viscera, pharynx, laryns, aortic arch, epiglottis, and base of tongue
SVA: taste from epiglottis
GVE: parasympathetics to viscera
SVE: Motor to constrictors of pharynx, palatine muscles, and intrinsic muscle of larynx (pharyngeal arch 4 + 6)
What is the tract for the vagus N.?
Medulla –> jugular foramen
How do you evaluate the vagus nerve?
sensory: gag reflex
motor: swallowing reflex, look for hoarseness, deviation of uvula when you say, “ahhhh” (they should elevate at the same time)
What is the function of the spinal accessory (CN 11)?
GSE: Motor to sternocleidomastoid + trapezius M.’s
What is the tract for the spinal accessory N.?
SC –> foramen magnum –> jugular foramen
What is the function of the hypoglossal nerve?
Motor to intrinsic tongue muscles + stylossus + hypoglossus + genioglossus
What is the hypoglossal nerve tract?
medulla –> hypoglossal canal –> travels with cervical plexus –> crosses occipital artery –> enters oral cavity
How do evaluate the hypoglossal CN 12?
motor only - protrude tongue - if lesioned the tongue will deviate to the ipsilateral side when you stick it out
Ex. left side is damaged
Superior salivatory nucleus (7) + Inferior Salvitory nucleus (9) + Posterior nucleus of vagus nerve (10) =
parasympathetic
