Other Cranial Nerves Flashcards
What is the functional category and function of the olfactory nerve (CN I)?
- Functional Category: Special somatic sensory
- Function: Olfaction
What is the functional category and function of the optic nerve (CN II)?
- Functional Category: Special somatic sensory
- Function: vision
What is the functional category and function of the oculomotor nerve (CN III)?
- Functional Category: Somatic motor
- Function: Levator palpebrae superior and all extraocular muscles except for superior oblique & lateral rectus
- Functional Category: Parasympathetic
- Function: Parasympathetic to pupil constrictor and ciliary muscle for near vision
What is the functional category and function of the Trochlear Never (CN IV)?
- Functional Category: somatic motor
- Function: Superior oblique muscle; cause depression and intorsion of the eye
What is the functional category and function of the trigeminal nerve (CN V)?
- Functional Category: General somatic sensory
- Function: Sensation of touch, pain, temp, joint position & vibration for the face, mouth, anterior 2/3 of tongue, nasal sinuses & meninges
- Functional Category: Branchial motor
- Function: Muscle of mastication & tensor tympani muscle
What is the functional category and function of the Abducens nerve (CN VI)?
- Functional Category: Somatic motor
- Function: Lateral rectus muscle; causes abduction of the eye
What is the functional category and function of the Fascial nerve (CN VII)?
- Functional Category: Branchial motor
- Function: Muscle of fascial expression, stapedius muscle, & part of digastric muscle
- Functional Category: Parasympathetic
- Function: Parasympathetic to lacrimal glands, and to sublingual, submandibular & all other salivary glands except parotid
- Functional Category: Visceral sensory (special)
- Function: Taste from anterior 2/3 tongue
- Functional Category: General somatic sensory
- Function: Sensation from a small region near the external auditory meatus
What is the functional category and function of the Vestibulocochlear nerve (CN VIII)?
- Functional Category: Special somatic sensory
- Function: Hearing & vestibular sensation
What is the functional category and function of the Glossopharyngeal nerve (CN IX)?
- Functional Category: Branchial Motor
- Function: Stylopharyngeus muscle
- Functional Category: Parasympathetic
- Function: Parasympathetics to parotid gland
- Functional Category: General somatic sensory
- Function: Sensation from middle ear, region near the external auditory meatus, pharynx & posterior 1/3 of tongue
- Functional Category: Visceral sensory (special)
- Function: Taste from posterior 1/3 of tongue
- Functional Category: Visceral sensory (general)
- Function: Chemo and baroreceptor of carotid body
What is the functional category and function of the vagus nerve (CN X)?
- Functional Category: Branchial motor
- Function: Pharyngeal muscles (swallowing) & laryngeal muscles (voice box)
- Functional category: Parasympathetic
- Function: Parasympathetic to heart, lungs & digestive tract down to the splenic flexure
- Functional Category: General somatic sensory
- Function: Sensation from pharynx, meninges & a small region near the external auditory meatus
- Functional category: Visceral sensory (special)
- Function: taste from epiglottis & pharynx
- Functional Category: Visceral sensory (general)
- Function: chemo & baroreceptors of the aortic arch
What is the functional category and function of the spinal accessory nerve (CN XI)?
- Functional Category: Branchial motor
- Function: Sternocleidomastoid (SCM) & upper part of trap
What is the functional category and function of the hypoglossal nerve (CN XII)?
- Functional Category: Somatic motor
- Function: intrinsic muscle of the tongue
Cranial nerve nuclei form what?
- 3 motor columns
- 3 sensory columns
- Each column serves a different motor or sensory cranial nerve function
Where are cranial nerve nuclei founded and run the length of what?
- Founded in embryological development
- Run the length of the brainstem
What are the 3 major branches of the Trigeminal Nerve (CN V)?
- Ophthalmic division
- Maxillary division
- Mandibular division
What are the 3 nuclei of the trigeminal nuclear complex?
- Mesencephalic trigeminal nucleus
- Chief trigeminal nucleus
- Spinal trigeminal nucleus
Where does the Trigeminal Nuclear Complex run and where does it receive input from?
- Runs from midbrain to upper c - spine
- Receive input from CN V (& CNN VII, IX & X)
Where is the Chief Trigeminal Sensory Nucleus located?
Lateral pons
What are the primary sensory neurons of the Chief Trigeminal Sensory Nucleus?
- Fine touch & dental pressure
- Synapse in chief trigeminal sensory nucleus
What are the secondary neuron of the Chief Trigeminal Sensory Nucleus?
- Crosses in brainstem
- Ascend in trigeminal lemniscus
- Synapses in the ventral posterior medial (VPM) of the thalamus
What is the tertiary neuron of the Chief Trigeminal Sensory Nucleus?
Travels to the face area of the primary somatosensory cortex
How is fine touch and dental pressure sensed?
Axons of the secondary neuron travel from the Chief sensory nucleus of CN V to the contralateral VPM via the trigeminal lemniscus
Where is the spinal trigeminal nucleus located?
Lateral pops, medulla & upper c-spine
Primary sensory neurons of the spinal trigeminal nucleus convey what? Where do they enter, decend and then synapse?
- Crude touch, pain & temp
- Enter lateral pons & descend in the spinal trigeminal tract
- Synapse in the spinal trigeminal nucleus
Describe the secondary neuron in the spinal trigeminal nucleus
- Crosses in brainstem
- Ascends in trigeminothalamic tract
- Synapses in the ventral posterior medial (VPM) of the thalamus
Where does the tertiary neuron travel of the spinal trigeminal nucleus?
Travels to the face area of the primary somatosensory cortex
How is the sensation of crude touch, pain & temp conveyed?
- Axons of the primary sensory neuron descending ipsilaterally in the spinal trigeminal tract
- Synapse in the spinal trigeminal nucleus
- Cross and ascend in the contralateral trigeminothalamic tract to the VPM of the thalamus
Where is Mesencephalic Trigeminal Nucleus & Tract located?
Lateral to periaqueductal gray of midbrain
Mesencephalic Trigeminal Nucleus receive proprioceptive input from where?
Muscles of mastication, tongue & extraocular muscles
What is the only case of the cell body of the primary sensory neuron being located in the CNS? (instead of in peripheral ganglia)
Mesencephalic Trigeminal Nucleus
What is the Mesencephalic Trigeminal Tract?
Ascending & descending fibers from mesencephalic trigeminal nucleus
What is the monosynaptic jaw jerk reflex?
- Descending fibers synapse in the motor trigeminal nucleus in the pons
- Presence of reflex is an abnormal repose (hyperreflexia)
How is proprioception conveyed?
Primary sensory neuron cell body sits within the central nervous system in the mesencephalic nucleus and ascends or descends as the mesencephalic trigeminal tract
Where is the Trigeminal Motor Nucleus located?
Upper to mid pons
What does the Trigeminal Motor Nucleus innervate?
Muscles of mastication & smaller muscles such as tensor tympani
The trigeminal motor nucleus receives bilateral UMN input from corticobulbar tract. So what occurs with:
- Unilateral UMN lesion?
- Bilareal UMN lesions?
- Unilateral: no deficits
- Bilateral: brisk jaw jerk reflex
What type of sensory loss is observed with damage to the spinal trigeminal nucleus in the brainstem?
Ipsilateral loss of fascial pain & temperature sensation
Lateral pons and medulla level injury often involve nearby spinothalamic tract. So what sensory loss can be seen with thesis injuries?
- Spinal trigeminal tract (ipsilateral loss of pain & temp in the face)
- Spinothalamic tract
(contralateral loss of pain & temp in the body)
What is Trigeminal Neuralgia?
Recurrent episodes of brief severe pain in distribution of one or the trigeminal nerve branches (most often v2 or v3)
What are some causes of Trigeminal Neuralgia?
- Often unknown
- Compression of trigeminal nerve
- MS
What are some treatment for Trigeminal Neuralgia?
- Meds
- Possible surgery
T/F: Neurological exam of someone with suspect Trigeminal Neuralgia can show normal fascial sensation
True
Where does the Fascial (VII) receive sensory input from and where does it synapse?
- Receive from region near external auditory meatus
- Synapse in trigeminal nucleus
Where do the preganlionic parasympathetic fibers of the fascial nerve originate?
Superior salivary nucleus (pons)
What are the 2 places the preganglionic parasympathetic fibers of the fascial nerve synapse?
- Sphenopalatin ganglion
- Submandibular ganglion
When the preganglionic parasympathetic fibers synapse on sphenopalatin ganglion where do postganglionic project where?
To lacrimal glands and nasal mucosa
When the preganglionic parasympathetic fibers synapse on submandibular ganglion where do postganglionic project where?
Submandibular gland and the sublingual salivary glands
What parasympathetic control does the fascial nerve have?
Control of glands producing tears & saliva
In CN VII Facial where do the primary sensory neurons receive sensation from and synapse where?
- Taste sensation from the anterior 2/3s of tongue
- Synapse in the rostral nucleus solitarius (gustatory nucleus)
(CN VII Facial) Where do the secondary neurons on taste sensation project & synapse?
- Project via the ipsilateral central tegmental tract
- Synapse bilaterally in the ventral posterior medial nucleus (VPM) of thalamus
(CN VII Fascial) Where do the tertiary neurons of taste sensation project?
Project to the cortical test area (inferior margin of post central gyrus adjacent to tongue somatosensory area and extends into fronto-parietal operculum & insula)
Where is the fascial nucleus located?
Branchial motor columns (pons)
What do facial nerve fascicles form?
Facial colliculus by looping dorsally around the abducens nucleus on the floor of the 4th ventricle
Facial Nucleus contains cell bodies of LMN that innervate what?
- Muscle of facial expression
- Part of digastric muscle (open jaw)
- Stapedius muscle (dampen loud noises)
In regards to facial nucleus what is the UMN (corticobulbar) input?
- Inferior part of face (contralateral motor cortex)
- Superior part of face (bilateral motor cortices)
What are the symptoms of the Upper Motor Neuron Lesion?
Weakness affecting mainly the inferior portions of the contralateral face
What are the symptoms of the Lower Motor Neuron Lesion?
Weakness affecting the entire ipsilateral half of the face
What is the most common fascial nerve disorder?
Bell’s Palsy
What are the symptoms of Bell’s palsy?
- Facial weakness (LMN type)
- Dry eye (parasympathetic)
- Retroauricular pain (sensory)
- Hyperacusis (stapedius)
- Ipsilateral taste loss to anterior tongue (taste)
What is Bell’s palsy, how is the recovery and what is the cause?
- Impaired function evolves over a few hours to day
- Gradual recovery (80% recover fully in 3 weeks)
- Cause: Unknown, possible viral/inflammatory mechanism
Where does the CN IX Glossopharyngeal (Brachial Motor) arise from?
Nucleus ambiguus in the medulla
What does the CN IX Glossopharyngeal (Brachial Motor) innervate?
- Stylopharyngeus muscle
- Elevates pharynx during talking & swallowing
- Contributes to gag reflex (along with CN X)
(CN IX Glossopharyngeal: Parasympathetic) Where do preganglionic parasympathetic fibers arise from, synapse and where do postganglionic fibers travel?
- Preganglionic parasympathetic fibers arise from the inferior salivary nucleus
- Synapse in otic ganglion
- Postganglionic parasympathetic fibers travel to the parotid gland
Where does CN IX Glossopharyngeal (General Somatic Sensory) receive sensory input from and where does it synapse?
- Posterior 1/3 of tongue, pharynx, middle ear & a region near external auditory meatus
- Synapse in trigeminal nucleus
In regards to CN IX Glossopharyngeal (Special Visceral Sensory) where does primary sensory neurons receive taste sensation from and synapse?
- Taste sensation from posterior 1/3 of the tongue
- Synapse in rostral nucleus solitarius
In regards to CN IX Glossopharyngeal (Special Visceral Sensory) where does the secondary neurons project and synapse?
- Project via the ipsilateral central tegmental tract
- Synapse bilaterally in the ventral posterior medial nucleus (VPM) of thalamus
On regards to CN IX Glossopharyngeal (Special Visceral Sensory) where does the tertiary neurons project?
Cortical taste area
In regards to CN IX Glossopharyngeal (General Visceral Sensory) what is input from?
Input from baroreceptors and chemoreceptors in the carotid body
In regards to CN IX Glossopharyngeal (General Visceral Sensory) where does it synapse and where is the information sent to?
- Synapse in the caudal nucleus solitarius of the medulla
- Info is sent to brainstem regions controlling HR, BP & RR
Where does CN X Vagus (Brachial Motor) arise from and innervate?
- Arises from nucleus ambiguous in the medulla
- Innervates (palate, pharynx, upper esophagus, larynx)
UMN innervation to the nucleus ambiguous is received from what?
Bilateral motor cortex
UMN innervation to the nucleus ambiguous is received from bilateral motor cortex except?
- Palate receives unilateral innervation from contralateral cortes
- Clinical Significance: Weakness in only the palate with UMN (corticobulbar) lesion, but with all LMN (nucleus of nerve)
Where does CN X Vagus (General Somatic Sensory) receive sensory input from?
- Pharynx
- Larynx
- Meninges
- Small region near external auditory meatus
Where does CN X Vagus (General Somatic Sensory) synapse?
Trigeminal nucleus
In regards to CN X Vagus (Special Visceral Sensory) where does the primary sensory neurons receive taste sensation and synapse?
- Taste sensation from the epiglottis & posterior pharynx
- Synapse in the rostral nucleus solitarius
In regards to CN X Vagus (Special Visceral Sensory) where does the secondary neurons project and synapse?
- Project via the ipsilateral central tegmental tract
- Synapse bilaterally in the ventral posterior medial nucleus (VPM) of thalamus
In regards to CN X Vagus (Special Visceral Sensory) where does the tertiary neurons project?
Cortical taste area
CN X Vagus (General Visceral Sensory) receive input from and synapse?
- Input from the baroreceptors & chemoreceptors in the aortic arch
- Synapse in the caudal nucleus solitarius of the medulla
CN X Vagus (General Visceral Sensory): The cardiorespiratory portion of the nucleus solitarius send projections where?
Brainstem regions controlling HR, BP & RR
The largest part of the vagus nerve provides parasympathetic innervation where?
To the heart, lungs & digestive tract down to the splenic flexure
Where do preganglionic parasympathetic fibers of CN X Vagus arise from?
Dorsal motor nucleus of CN X in the medulla
Where are postganglionic parasympathetic neuron of the CN X Vagus found?
Terminal ganglia near the effector organs
Where do CN XI Spinal Accessory Nerve (Brachial Motor) fibers arise from?
Spinal accessory nucleus that protrudes laterally between the dorsal & ventral horns of the spinal cord
Where do CN XI Spinal Accessory Nerve (Brachial Motor) nerve rootlets leave the spinal cord?
Between dorsal & ventral nerve roots just dorsal to dentate ligament
Where does CN XI Spinal Accessory Nerve (Brachial Motor) ascend and exit?
- Ascend through the foramen magnum to the intracranial cavity
- Exits the cranium via jugular magnum to supply the sternocleidomastoid and upper trap muscle
UMN lesion of CN XI Spinal Accessory Nerve nucleus shows what?
- UMN input to spinal accessory nucleus
- Upper trap muscle innervated primarily by contralateral cortex
- UMN lesion show markedly weak shoulder elevation
The SCM muscle receives bilateral innervation from CN XI Spinal Accessory Nerve so UMN lesion would show what?
Relative preservation in head turning strength
Where is the hypoglossal nucleus located?
Midline on the floor of the 4th ventricle in the medulla
Where does UMN input to the hypoglossal nucleus arise from?
Tongue region of primary motor cortex, descend in the corticobulbar pathway & decussate close to the hypoglossal nucleus
Where does the CN XII Hypoglossal Nerve (Somatic Motor) exit and innervate?
- Exits as multiple rootlets between the pyramid and inferior olivary nucleus
- Innervates all intrinsic & extrinsic tongue muscles except for palatoglossus (CN X)
Unilateral tongue weakness causes the tongue to deviate?
Towards the weak side with protrusion
UMN hypoglossal lesion causes what?
Tongue will be weak & deviate contralateral to the lesion
LMN hypoglossal lesion causes what?
Tongue will be weak & deviate ipsilateral to the lesion
Cortex & Corticobulbar input is provided where?
Contralaterally
- Lower portion of the face (CN VII)
- Soft palate (CN IX, X)
- Upper trap (CN XI)
- Tongue (CN XII)
What is the afferent & efferent from corneal reflex?
- Afferent: Trigeminal (V)
- Efferent: Facial (VII)
What is the afferent & Efferent from jaw jerk reflex?
- Afferent: Trigeminal (V) (Mesencephalic)
- Efferent: Trigeminal (V) (motor)
What is the afferent & efferent from gag reflex?
- Afferent: Glossopharyngeal (IX) & Vagus (X)
- Efferent: Vagus (X)