Lecture 6 Flashcards
Cranial Nerve Rule #1: Parasympathetic GVE fibers reside ONLY in?
- CN III: Oculomotor
- CN VII: Facial
- CN IX: Glossopharyngeal
- CN X: Vagus
What is the associated ganglion of CN III?
ciliary ganglion
What is the associated ganglion with CN VII?
Pterygopalatine & Submandibular Ganglion
What is the associated ganglion with CN IX?
Otic Ganglion
What is the associated ganglion with CN X?
Various ganglia near visceral organs
Cranial Nerve Rule #2: Branchial Motor (BE/SVE) fibers reside ONLY in nerves associated with pharyngeal (branchial) arches, which cranial nerves are these?
- CN V3
- CN VII
- CN IX
- CN X
Major sensory nerve of the face
CN V - trigeminal
What is the pathway of the CN V?
- Begins at pons and travels superiorly/anteriorly towards face
- Splits into three terminal divisions at “trigeminal ganglion” in middle cranial fossa
V1 = Ophthalmic
V2 = Maxillary
V3 = Mandibular
What is CN V1?
opthalmic
What is CN V2?
maxillary
What is CN V3?
mandibular
Each terminal branch exits the skull via a different foramen and innervates a different region of the face for which cranial nerve?
CN V
What code is CN V1? What does it innervate?
GSA
- upper face
What code is CN V2? What does it innervate?
GSA
- mid face
What code is CN V3? What does it innervate?
GSA
- lower face
BE/SVE
- arch 1
- muscles of mastication
What sensation is the spinal nucleus of the trigeminal nerve associated with?
Pain the Tem & light touch
What is the pathway, foramina, and function of CN V1?
- Pathway: originates at trigeminal ganglion, ophthalmic division passes through the cavernous sinus, exits via superior orbital fissure, & has many additional branches from there
- Foramina: Superior orbital fissure
- Function: GSA Modality
What are the general sensory areas of CN V1?
- forehead
- anterior scalp
- upper eyelid
- tip of the nose
- anterior nasal cavity
- frontal & ethmoidal sinuses
- dura mater of anterior cranial fossa
How do you test for CN V1?
- Test sensation of forehead
- CN V1 – corneal reflex
What is the pathway, foramina, and function of CN V2?
- Pathway: passes through the cavernous sinus, exits skull via foramen rotundum to innervate face
- Foramina: Rotundum
- Function: GSA Modality
What are the general sensory area of CN V2?
- the sides of the nose
- lower eyelids
- upper lip
- posterior nasal cavity
- teeth of the upper jaw
- maxillary sinus
- nasopharynx
- palate
- dura of the middle cranial fossa
How do you test for CN V2?
Test sensation of lateral nose, cheek and upper jaw
What is the pathway, foramina, and functions of CN V3?
- Pathway: not associated with cavernous sinus, exits skull via foramen ovale to innervate lower face
- Foramina: Ovale
- Function: GSA Modality & BS/SVE
What are the general sensory areas of CN V3?
- lower lip
- chin
- lower face & cheek
- anterior external ear
- teeth of mandible
- mucous membranes of cheek
- anterior 2/3 of tongue
- dura in the middle cranial fossa
The CN V extensively innervates the __ __
dura mater
What are muscles does CN V3 innervate/control?
Arch 1
Voluntary motor control to muscles of mastication
- Temporalis
- Masseter
- Medial pterygoid
- Lateral pterygoid
Collectively these muscles open/close the mandible for chewing action
The __ __ muscle, innervated by the mandibular branch of CN V, connects the auditory tube to the malleus handle.
tensor tympani
What is the role of tensor tympani?
Increases the tension in the tympanic membrane, thus protecting it from excessive vibration in response to loud sounds –> dampens noise produced by chewing in own ear
sensation of pain elicited without presence of noxious stimuli
neuralgia
What happens during trigeminal neuralgia?
trigeminal nerve perceives sensations as pain - Intermittent attacks of severe, sharp, stabbing pain “electric shock”
What branches does trigeminal neuralgia often affect?
CN V2 & V3
- GSA code ONLY (no motor)
T/F: Trigeminal neuralgia shows bilateral distribution
False, unliateral
What is trigeminal neuralgia aggravated by?
- Exposure to cold
- Chewing
- Brushing teeth
- Talking
- Touching face
Where do you test for sensation of CN V1?
forehead
Where do you test for sensation of CN V2?
cheek
Where do you test for sensation of CN V3?
jaw
How do you test for CN V3 motor?
ask pt to move muscles of mastication
What are the codes associated with CN VII? What areas of the body are they associated with?
- BE/SVE axons to muscles of facial expression (arch II)
- SVA axons (taste) from the anterior 2/3rds of the tongue
- GVE axons to the submandibular, sublingual and lacrimal glands
- GSA axons for the “patch” of skin behind the ear
What is the pathway of CN VII?
- Facial nerve originates from the pons and first exits skull through the internal acoustic (auditory) meatus winding through the petrous portion of the temporal bone (facial canal) - Infection in the middle/inner ear can impact CN VII
- Within temporal bone, nerve gives off several intracranial branches
- Remaining nerve will exit the cranial base via the stylomastoid foramen
Which nerve is impacted by middle/inner ear infections?
CN VII
Which foramen does CN VII pass through?
Internal Acoustic Meatus AND Stylomastoid Foramen
Once CN VII exits the skull, it gives rise to 6 __ __?
extracranial branches
The __ attaches to the stapes and helps to dampen intense/loud sounds
Stapedius
Which cranial nerve innervates stapedius?
CN VII
results from trauma to the facial nerve, such as a viral meningitis infection
Bell’s palsy
What are the symptoms of Bell’s Palsy?
- Weakness, twitching, or flaccid paralysis of facial muscles, including drooping of the eyelid and corner of the mouth. These symptoms would result from damage to the SVE portion of the facial nerve.
- Dry eye or mouth. These symptoms would result from damage to the GVE component of the nerve.
- Impairment of taste resulting from damage to the SVA component of the nerve
protects eyes from foreign bodies
corneal reflex
What 2 cranial nerves can be tested with corneal reflex?
Sensory arc: CN V1 (touch to surface of cornea)
Motor arc: CN VII (orbicularis oculi)
What is the desired response of corneal reflex test?
BILATERAL regardless of input side
How do you test the corneal reflex?
Cotton gauze touched to cornea of R eye should result in blink/closure of BOTH eyes
What could dull the corneal reflex, giving a false positive?
contact lenses
Cotton gauze touched to L eye, only R eye blinks –>
means sensory signal worked, but L motor did not work
Cotton gauze touched to L eye, and no eyes blink –>
means sensory input did not work
How do you test for CN VII?
- corneal reflex
- test muscles of facial expression
- test taste
What is different about the vestibulocochlear nerve?
two separate nerves that travel together
What is the pathways of the vestibulocochlear nerve?
Begins at base of pons and exits cranium via internal acoustic meatus. Terminates as separate nerves in inner ear
What is the foramina of vestibulocochlear nerve?
internal acoustic meatus
What is the function of vestibulocochlear nerve?
Special Somatic Afferent (SSA) for two senses:
- Hearing (Cochlear)
- Balance & equilibrium (Vestibular)
What is the pathway of CN IX?
- Nerve emerges from the brainstem in the lateral medulla and exits the posterior cranial fossa through the jugular foramen.
- Majority of nerve remains extracranial to innervate structures of face and throat
What is the foramina of CN IX?
jugular foramen
What are the functions (codes) of CN IX?
- BE/SVE – voluntary motor: axons innervate stylopharyngeus (swallowing muscle)
- SVA – special visceral afferent: axons carry taste perception from the posterior 1/3 of the tongue
- GVE – general visceral efferent: axons innervate the parotid gland via otic ganglion (secretomotor function)
- GVA – general visceral afferent: axons from the carotid body (visceral sensation from carotid body for chemoreception – maintaining BP)
- GSA – general somatic afferent: sensory from skin posterior to the ear, posterior 1/3 of tongue, and the afferent part of the gag reflex
What is the pathway of CN X?
Nerve emerges from the brainstem in the lateral medulla and exits the posterior cranial fossa through the jugular foramen
What foramina does CN X exit?
jugular foramen
What are the functions (codes) of CN X?
- BE/SVE – voluntary motor: axons innervate the majority of the muscles of the pharynx, larynx and soft palate (moving food towards esophagus during swallowing)
- SVA – special visceral afferent: axons from skin posterior to ear, dura in posterior cranial fossa, mucous membranes of pharynx & larynx
- GVE – general visceral efferent: axons from thoracic & abdominal viscera & aortic body - Chemoreceptors – blood content & Baroreceptors – blood pressure
- GVA – general visceral afferent: axons (taste) from the root of tongue and epiglottis region (throat)
- GSA – general somatic afferent: to thoracic and abdominal viscera up to left colic flexure. Synapse is in or around target organ.
The gag reflex is initiated in response to stroking the back of the throat and is mediated by the __ nerve
vagus
helps prevent choking (Protective response that prevents oral contents from entering the throat except as part of normal swallowing)
gag reflex
What nerves can be tested by gag reflex?
- Sensory arc: CN IX (touch to base of throat)
- Motor arc: CN X (motor response of pharynx)
What is the desired response of the gag reflex?
BILATERAL regardless of input side (contraction of soft palate muscles of BOTH sides)
uvula will deviate to the intact side (away from side of injury) - gag reflex
CN X motor problem
NO RESPONSE (soft palate muscles do not contract at all) - gag reflex
CN IX sensory problems
What is the pathway of CN XI?
Nerve begins at medulla and exits cranium via jugular foramen
What is the foramina of CN XI?
jugular foramen
What is the function of CN XI?
voluntary motor to Sternocleidomastoid and Trapezius muscles
- SCM – contralateral rotation of head
- Traps – shoulder “raises”
General Somatic Efferent (GSE)
What is the pathway of CN XI?
Nerve begins at medulla and exits cranium via hypoglossal canal
What is the foramina of CN XII?
Hypoglossal canal
What is the function of CN XII?
voluntary motor to muscles of the tongue
General Somatic Efferent (GSE)
The cortex normally send bilateral innervation to cranial nerve motor nuclei. The one exception is innervation of the __ muscle, which is contralateral
genioglossus
What is injured if the tongue deviates to left?
left CN XII or right motor cortex
What is injured if the tongue deviates to right?
right CN XII or left motor cortex
What are common causes of hypoglossal nerve injury?
-Injuries are fairly rare
- Posterior neck dissection
- Fracture of atlanto-occipital joint
How does the patient present with CN XII injury?
- Tongue deviated to same side as injury due to atrophy of muscle muscles
- “lick your wounds” presentation
- Dysphagia (difficulty swallowing)
- Slurred speech
- Fasciculation on the tongue – “bag of worms” appearance
How do you test for CN XII?
- “stick out tongue”
- ask pt to open mouth and see how it looks inside the mouth
What sensation is the chief or principal nucleus or main sensory nucleus of the trigeminal sensory nuclei associated with?
discriminative sensation and light touch as well as conscious proprioception
What sensation is the mesencephalic nucleus of the trigeminal sensory nuclei associated with?
unconscious proprioception
What are the intracranial branches of the facial nerve?
- chorda tympani carries GVE & SVA
- greater petrosal nerve carries GVE
What is the pathway of the chorda tympani nerve of the facial nerve? What does it carry?
- Branches off main nerve in the facial canal (inside skull)
- SVA = Special visceral afferent carrying taste perception from the anterior 2/3rds of the tongue
- GVE = General visceral efferent secretomotor of the submandibular and sublingual glands
- Via submandibular ganglion = Saliva production
What is the pathway of the greater petrosal nerve of the facial nerve? What does it carry?
- Exits the petrous portion of the temporal bone where parasympathetic axons synapse in the pterygopalatine ganglion.
- GVE = General visceral efferent
- Secretomotor to lacrimal gland of eye (tear production)
The primary gustatory region of the cortex is found in: the?
insula
What are the extracranial branches of the facial nerve?
- BE/SVE Modality = Voluntary motor control to muscles of facial expression
- GSA Modality = GAS to skin behind the ear (posterior auricular branch)
What are the branches of the BE/SVE modality extracranial branch of the facial nerve?
- Temporal
- Zygomatic
- Buccal
- Mandibular
- Cervical
The BE/SVE branch of the vagus nerve travels posterior to the thyroid, what are common causes of injury to this nerve?
- tumor or after surgical intervention of the thyroid
- Bronchial carcinoma
- Aortic arch aneurysm
How would the patient present with injury to the BE/SVE branch of the vagus nerve?
- Hoarse voice
- Vocal changes (dysphonia)
- Difficulty producing speech
What is the job of the GVE branch of the vagus nerve?
to promote rest & digest (decrease HR, respiratory rate, stimulate digestion & secretion of enzymes)