Lectures 2 & 3: Cranial Nerves Flashcards
Where are the nuclei of cranial nerve III-XII?
Brainstem
What are the cranial nerves?
1: Olfactory
2: Optic
3: Oculomotor
4: Trochlear
5: Trigeminal
6: Abducens
7: Facial
8: Auditory: vestibular/cochlear
9: Glossopharyngeal
10: Vagus
11: Spinal accessory
12: Hypoglossal
What can a cranial nerve do?
Function solely for sensation or motor
Function as a combination of sensory, motor, and autonomic
What nerves function as sensory only?
I, II, VIII
What nerves function as motor only?
III, IV, VI, XI, XII
What nerves function as mixed sensory and motor?
V, VII, IX, X
What nerves function as autonomic?
III, VII, IX, X
What are the general somatic sensory/afferent nerves?
5, 7, 9, 10
What are the special somatic sensory/afferent nerves?
2, 8
What are the special somatic sensory/afferent nerves responsible for?
Sight and hearing
What are the general visceral sensory/afferent nerves?
7, 9, 10
What are the special visceral sensory/afferent nerves?
1, 7, 9, 10
What are the special visceral sensory/afferent nerves responsible for?
Smell and taste
What are the general somatic motor/efferent nerves?
3, 4, 5, 6, 7, 9, 10, 11, 12
What are the general visceral motor/efferent nerves?
3, 7, 9, 10, (+/-) 11
Which nerve does sensation to the face?
5
Which nerves share the solitary tract and nucleus?
7, 9, 10
Which nerves share nucleus ambiguus?
9, 10, 11
What is the olfactory nerve made of?
Biopolar neurons
How are the bipolar neurons replaced?
Stem cells
Where does the olfactory nerve come from?
Olfactory mucosa and vomeronasal organ
What is special about the pathway between the olfactory mucosa and vomeronasal organ?
It is the only pathway that does not pass through the thalamus
What does the olfactory nerve pass through?
Cribriform plate
What is the synapse of the olfactory nerve on?
Olfactory bulb neurons
What happens when the olfactory nerve hits the olfactory bulb neurons?
Send axons caudally via lateral and medial olfactory tract
Where does the olfactory nerve terminate?
In the piriform lobe for olfactory perception and hypothalamus OR reticular formation for behavior and emotion
Is the optic nerve an actual nerve?
Not technically. It is truly a tract
Since the optic nerve is truly a tract and not a nerve, the myelin is placed by which cell?
Oligodendrocytes
What axons come together to form the optic nerve?
Rods (night vision) and cones (color vision)
How does the optic nerve enter the skull?
Via optic foramen and canal
What forms the optic chiasm?
Right and left optic nerve come together in front of hypophysis
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in primates?
50%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in cats?
65%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in dogs?
75%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in ungulates?
80-90%
What percentage of the optic nerve decussates (cross to the other side) and becomes the optic tract in fish?
100%
What does the optic nerve become once it crosses to the other side?
Optic tract
What is the post chiasm pathway?
Optic tract to lateral geniculate nucleus in the thalamus OR optic tract to midbrain for reflex pathways
What type of species have more laterally placed eyes? Why?
Prey
Giving them a wide field of view
Greater percentage of fibers decussating at the chiasm
Poor binocular vision
What is the vision of predators like?
Smaller field of view
Better binocular vision due to decrease decussation
What cranial nerves control the extra-ocular muscles?
3, 4, 6
What muscles does cranial nerve 3 (oculomotor) innervate?
Dorsal, medial, ventral recti
Ventral oblique
What muscle does cranial nerve 4 (trochlear) innervate?
Dorsal oblique
What muscles does cranial nerve 6 (abducens) innervate?
Lateral rectus
Retractor bulbi
What are the 2 nuclei of the oculomotor nerve?
Oculomotor motor nucleus and parasympathetic nucleus of CN3 in the midbrain
Where does the oculomotor go through the skull?
Orbital fissure
What are the 2 parts of the oculomotor nerve?
Somatic motor and parasympathetic motor
What muscles does the somatic oculomotor nerve innervate?
Levator palpable superioris Dorsal rectus Medial rectus Ventral rectus Ventral oblique
Where is the nucleus of the parasympathetic oculomotor nerve located?
In midbrain rostral to somatic oculomotor nucleus
What is the nucleus of the trochlear nerve?
Motor nucleus in midbrain
Where does the trochlear motor run?
On the dorsal aspect of brain stem and decussates
The trochlear nerve is the only cranial nerve to do certain things. What are those things?
Exit from the brainstem dorsally
Innervate muscles solely on opposite side from its nucleus
Where does the trochlear nerve go through the skull?
Orbital fissure
What does the somatic motor of the trochlear nerve innervate?
Dorsal oblique
Where is the motor nucleus of the abducens nerve?
In rostral medulla
Where does the abducens nerve go through the skull?
Orbital fissure
What muscles does the abducens nerve innervate?
Lateral rectus
Retractor bulbi
What are the 3 branches of the trigeminal nerve?
Opthalamic (GSA)
Maxillary (GSA)
Mandibular (GSA, GSE)
Where is the motor nucleus of CN 5?
Pons
What does the mandibular branch of the trigeminal nerve innervate?
Masticatory muscles
What are the muscles that the mandibular branch of the trigeminal nerve innervates?
Temporalis Masseter Pterygoid Mylohyoideus Tensor tympani Tensor veli palatini Digastricus
Where does the mandibular branch of the trigeminal nerve go through the skull?
Oval foramen (inside) and caudal alar foramen (outside)
Where does the ophthalmic branch of the trigeminal nerve go through the skull?
Orbital fissure
Where does the maxillary branch of the trigeminal nerve of through the skull?
Round foramen (inside) and rostral alar foramen (outside)
Where is the trigeminal ganglia located?
In the trigeminal canal at the apex of the petrous temporal bone inside the skull
What are the nuclei of the trigeminal nerve and where are they located?
Mesencephalic, pontine, and spinal sensory nuclei located from midbrain through brainstem
Where does the trigeminal nerve decussate and travel to?
Somatosensory cortex via trigemina lemniscus and thalamus OR other brainstem nuclei for reflex activity
What are the actions of the facial nerve?
Somatic motor
Parasympathetic sensation
Parasympathetic motor
Where does the sensory portion of the facial nerve occur?
Concave surfaces of ear and ear canal
What does the somatic motor of the facial nerve innervate?
Muscles of facial expression, orbicularis oculi, caudal diagstricus, and stapedius
Where is the motor nucleus of the facial nerve located?
Medulla
Where does the facial nerve go through the skull?
Internal acoustic meatus to facial canal in petrosal portion of the temporal bone
Where does the facial nerve out of the skull?
Via stylomastoid foramen at base of the external ear canal
What does the parasympathetic sensation of the facial nerve do?
Taste palate and rostral 2/3 of tongue (SVA)
Middle ear and blood vessels of the head (GVA)
What is the nucleus of the facial nerve and where is it located?
Solitary tract and nucleus in the brainstem
What is the ganglion of cranial nerve 7?
Geniculate ganglion
What are the ganglia of cranial nerve 7?
Pterygopalatine, mandibular, and sublingual ganglia
What are the salivary glands innervated by cranial nerve 7?
Lacrimal and nasal glands
Mandibular glands
Sublingual glands
How do sound waves travel?
Through the external ear and hit the tympanic membrane, where sound waves are converted into mechanical vibrations via the malleus—incus —- stapes of middle ear— vestibular/oval window of cochlea of inner ear
What do vibration from vestibular window cause?
Swaying of “hair cell” of cochlea
Where are the cochlear nerve cell bodies of cranial nerve 8?
Spiral ganglion
What does the cochlear nerve go through?
Internal acoustic meatus
Where are the dorsal and ventral cochlear nuclei of the cochlear nerve located?
Medulla
What can the cochlear nerve travel to?
Lateral lemniscus to thalamus to auditory cortex of temporal lobe OR To midbrain, brainstem, and spinal cord for reflex activity
What are the receptors of the vestibular nerve?
Hair cells in the remaining parts of the inner ear (utricle, saccule, and semicircular canals)
What do the vestibular receptors respond to?
Movement and velocity of the head
What are the cell bodies of the vestibular nerve?
Vestibular ganglion
Where do the axons of the vestibular nerve go to?
Vestibular nuclei in medulla
Flocculonodular lobe of cerebellum
Where can the vestibular nerve travel to?
Spine for balance OR To extra ocular muscle CN nuclei for conjugate eye movement via medial longitudinal fasciculus
What is the nucleus of the somatic motor of the glossopharyngeal nerve?
Nucleus ambiguus in medulla (most rostral aspect)
Where does the somatic motor of the glossopharyngeal nerve come out?
Via jugular foramen and tympanooccipital fissure
What does the somatic motor of the glossopharyngeal nerve innervate?
Pharyngeal muscles
What does the parasympathetic sensation of the glossopharyngeal nerve do?
Taste from mucosa of pharynx and caudal 1/3 tongue (SVA)
Baroreceptors and chemoreceptors from carotid sinus and body (GVA)
What is the ganglia of CN 9?
Distal ganglia
What does the parasympathetic sensation of CN 9 go through?
Tympanoocipital fissure and jugular foramen
What is the nucleus of CN 9?
Solitary tract and nucleus in the medulla
Where is the nucleus of the parasympathetic motor of CN 9?
Medulla
What is the ganglion of the parasympathetic motor of CN 9?
Otic ganglion
What are the salivary glands involved with the parasympathetic motor of CN 9?
Parotid and zygomatic
What is the nucleus of CN 10?
Nucleus ambiguus in medulla (middle)
Where does the somatic motor of CN 10 come out?
Jugular foramen and trympanoocipital fissure
What does CN 10 innervate?
Palate
Pharynx
Esophagus
Larynx
What do the parasympathetic sensation of the vagus nerve do?
Pharynx, larynx, thoracic, and abdominal cavities (GVA)
Taste caudal pharynx and larynx (SVA)
What is the ganglia of CN 10?
Distal
What does the vagus nerve go through?
Typanooccipital fissure and jugular foramen
What is nucleus of CN 10?
Solitary tract and nucleus in medulla
Where is the nucleus of CN 10?
Medulla (parasympathetic nucleus of CN 10)
Where does the parasympathetic motor of CN 10 go out?
Jugular foramen and tympanooccipital fissure
What does the paraasympathetic motor of the vagus nerve go to?
Various peripheral ganglia to innervate blood vessels, cardiac and smooth muscles and glands of thoracic and abdominal cavities as well as pharynx
What is the nucleus of the somatic motor of the internal branch of the spinal accessory nerve?
Caudal aspect of nucleus ambiguus in medulla
What does the internal branch spinal accessory nerve join?
Vagus nerve for larynx and esophagus via recurrent laryngeal nerve
What is the nucleus of the external branch of CN 11?
Accessory nucleus of C1-8
Where do the spinal roots of the external branch of CN 11 travel?
Cranially through foramen magnum
Where does the external branch of CN 11 exit?
Jugular foramen and tympanoocipital fissure
What does the exteernal branch of CN 11 innervate?
Trapezius Sternocephalicus Cleidocephalicus Cleidocervicalis Cleidomastoideus Sternomastoideus
What is the parasympathetic motor of CN 11?
Internal branch
Where does the parasympathetic motor of CN 11 exit?
Via jugular foramen and tympanooccipital fissure
What does the parasympathetic motor of CN 11 innervate?
Esophagus and larynx
Where is the nucleus of the hypoglossal nerve?
Medulla (hypoglossal motor nucleus)
What does CN 12 go through?
Hypoglossal canal of the skull
What muscles does CN 12 innervate?
Skeletal muscles of the tongue
