Cranial Nerves Flashcards
,What are the 3 major cranial nerves serving special sense organ?
I- olfactor
II- Optic
VIII - Vestibulocochlear
They develop in part from epidermal neurogenic placodes
are not parts of other cranial sensory-motor nerve
What are the 4 somatic motor nerves that move the eye and tongue?
III - Oculomotor (exits from venral midbrain)
IV - Trochlear (exits dorsally and decussates)
VI - Abducens (emerges caudal to VII)
XII - Hypoglossal
- have no affiliated sensory ganglia, thus they have only efferent components
- sensory fibers in the peripheral parts of these nerves are “hitch-hikers” from nearby mixed nerves
- are more (XII, VI, III) or less (IV) comparable to ventral roots of spinal nerves
What are the 4 mixed branchial nerves that move and sense jaws, face, pharynx, and larynx?
V - trigeminal
VII - Facial
IX - Glossopharyngeal
X - Vagus
This nerve is the only special motor nerve that is cranial only in a roundabout way and innervates the sternocleidomastoid and trapezius muscle
XI - Spinal Accessory
What is the Otic Placode?
auditory and vestibular sensory haircells and ganglion cells
Involves Cranial nerve VIII
What is the Optic Placode?
Lens
Involces CN II
WHat is the olfactory placode?
Central Projecting sensory cells
This structure is located at the diencephalon wall. What is it and what does it contain?
This is the Optic Vesicle
contain sensory cells and ganglion cells
What does CN I (Olfactory Nerve) consist of?
consists of the central-projecting axons of bipolar olfactory sensory neurons (= olfactory receptor cells) situated in the olfactory epithelium.
The axons collect as fine bundles that traverse the olfactory foramina in the cribriform plate of the ethmoid bone to reach the olfactory bulbswhere they synapse on second order olfactory neurons.
This “Cranial Nerve” is actually a CNS tract, not peripheral nerve and covered by meningies. Located in the nasal cavity?
CN I (Olfactory)
It is covered with dura, arachnoids, and pia mater
Patient comes in reporting that he has difficulty smelling after doing some drugs. What is one possible diagnosis that can be considered?
Anosmia (loss of sense of smell)
This occurs when there is Damage to the olfactory sensory epithelium or disruption of the fibers at the cribiformplate
To exam the function of CN I you will expose the patient to test odorants
What is the path of the Optic nerve (CN II)
begin at the retina and extend to the optic chiasma, where approximately half of the optic fibers cross to the other side. The fibers continue as the optic tracts and most of them terminate by synapsing in the lateral geniculate nuclei of the thalamus.
What is different about the Optic nerve compared to some other cranial nerves?
The retina and optic nerves arise from the walls of the embryonic diencephalon. Accordingly, the optic nerves are brain tracts, not peripheral nerves.
Most of the axons that make up the optic nerve come from where? axons of retinal ganglion cells.
axons of retinal ganglion cells.
This nerve is actually made of two nerves. It enters the brain at the pontomedullary junction, just dorsal to the root of the VIIth nerve.
CN: VIII
(Vestibulocochlear Nerve)
The VIIIth nerve fibers pass peripherally to into the _____, accompanied by the VIIth nerve, via the __________.
Temporal bone
Internal Acoustic meatus
What does the cochlear nerve (portion of CN VIII) comprise of?
afferent axonal processes of cells in the spiral ganglion which innervate the auditory haircells of the spiral organ(Organ of Corti)
as well as,
efferent axons of central neurons located in the superior olivary/periolivarynuclei that form the olivocochlear bundle
The Vestibular nerve (part of CN VIII) comprises of?
afferentaxonal processes of cells in the vestibular ganglion (Scarpa’s)which innervate:
vestibular hair cells of the ampullae of the semicircular canals, sensing angular acceleration
vestibular hair cells of the maculae of the saccular and utricular otoliths, sensing linear acceleration
as well as,
efferent axons of central neurons located in two vestibular efferent nuclei
Where do the afferent fibers of the cochlear nerve project?
project to the lowest order brainstem auditory centers, the dorsal and ventral cochlear nuclei
The vestibular nerve afferent fibers project to where?
to the vestibular nuclei (superior, medial, lateral and descending) and to the vestibulocerebellum
The vestibular nuclei connect to what other structures besides the Vestibular nerve afferetn fibers?
connect with brainstem, spinal and cerebellar centers involved in postural and gaze control (among others)
MLF and Vestibulospinal tracts are what?
Major central vestibular pathways
They lead to extrocular and cervical motor nuclie controlling eye and head movements
How do you test Vestibular function?
Routine auditory test (done with a tuning fork)
or
asking the patient to walk a straight line
or
observing eye movements during introduction of cool or warm water into the external ear canal.
What is the Caloric Test?
Observing eye movement during introduction of cool/warm water.
induces alternating eye movements (Nystagmus) by generating convection in the endolymph of the horizontal semicircular canal. The caloric vestibulo-ocular reflex is especially useful in testing brainstem function in comatose patients.
What is a complication of the CN III?
This is the oculomotor nerve and it also has parasympathetic components - to smooth muscle of the eye
What are the Embryonic Origins of Striated Cranial Muscles Innervated by Somatomotor Cranial Nerves III, IV, VI and XII?
- Dorsal head mesoderm in front of the ear (pro-otic) produces the extraocular muscles, innervated by cranial nerves III, IV and VI
- Occipital somites 1-4 give rise to a migratory stream of myocytes that travel ventrally into the floor of the oral-pharyngeal region to produce the tongue muscles innervated by CN XII.
Which ganglion does CN III innervate?
parasympathetic ciliary ganglion.
Side note: Innervates most of the striated and smooth muscles of the eye, thus has both somatic and visceral (parasympathetic) motor fibers
The parasympathetic ciliary ganglion and the occular smooth muscles innervated by CN III are derived from what?
Neural crest
The CN III roots emerge from where?
emerge from the ventral midbrain, on either side of the posterior perforated substance, and between the mamillarybodies and the pontine fibers
Edinger-Westphal Nucleus* (GVE)
Preganglionic parasympathetic neurons in the Edinger-Westphal Nucleus innervate post-ganglionicneurons in the ciliary ganglion
Oculomotor Nucleus (GSE)
Motor neurons innervate:
4 striated muscles that move the eye
- superior rectus
- inferior rectus
- medial rectus
- inferior oblique
1 striated muscle that elevates the upper eyelid
-levator palpebrae superioris
Ciliary ganglion neurons innervate 2 smooth muscles in the eye?
- thepupillarysphincter musclewhich constricts the pupil (red)
- theciliary muscle which regulates the curvature of the lens (blue)
What are the characteristics signs of a unilateral c=occulomotor nerve palsy?
“down out syndrome”
Ptosis (drooping) of the upper eyelid, due to lack of action of the levatorpalpebrae superioris
Dilation of the pupil due to loss of sphincter pupillae function
Depressed and abducted resting eye position due to the IVthand VIthnerve eye muscles acting unopposed
CN IV (Trochlear) innervates only what?
ONLY the superior oblique muscle
(contains somatic motor fibers)
The trochlear nerve received that name because the superior oblique muscle passes through a pulley (L., trochlea) before inserting on the globe.
What is the direction of the Trochlear nerve roots?
roots exit dorsallyat the midbrain/hindbrain junction and cross to the opposite side (right to left, left to right)
Where is the trpchlear nuclei located?
trochlear nuclei are located near the midline beneath the most superior part of the fourth ventricle
(green arrow)
*look at picture*
What are the two main actions of the superior oblique muscle?
Depresses and medially rotate (in-tort) the eye
Trochlear Nerve palsy
Most notable effect of loss of SO muscle function due to trochlear nerve palsy is a persistent laterally rotated eye posiition (ex-torsion)
The laterally rotated eye position may be compensated for by tilting the head away from the direction of the non-functional SO mucle.
This nerve only innervates the lateri rectus muscle, which Abducts the eye
CN VI (Abducent nerve)
Contains only somatic sensory fibers
Where does the root of CN VI emerge from?
emerge near ventral midline at ponto-medullary junction
Loss of function of the abducens nerve leads to what?
It causes the eye to remain adducted during forward gaze (i.e. inability to abduct)
If this occurs bilaterally = crossed eye
What exactly has many oppourtunities to disrupt Cranial Nerve II, III, IV, and VI?
The Cavernous Sinus
Because of the close proximity of the pituitary and internal carotid to the optic chiasma and the nerves to extraocular muscles (III, IV, VI), visual and eye movement deficits are often involved in cases of pituitary tumors, internal carotid anurysmsor thrombosis in the cavernous sinus.
What is Cranial nerve XII
This is the hypoglossal nerver
Somatomotor innervation of the tongue muscles
This nuclei is located in the medulla oblangata, just below the ventricle
Hypoglossal motor nucleus
What is the direction of the Hypoglossal nerve?
The nerve exits the skull via the hypoglossal foramen, between the jugular foramen and the occipital condyle
The rootlets exit the brain over a long distance along the groove separating the pyramids and inferior olive. They are followed by the rootlets of C1
The motor fibers of C1 that travel with CN XII enter where together?
the ansacervicalis (blue)
Where they innervate the thyrohyoid (red) and geniohyoid (green) muscles
What are the muscle that are innervated by the hypoglossal nerve?
Genioglossus m.
Hyoglossus m.
Styloglossus m.
Chondroglossus m.
intrinsic tongue muscles
(but not the palatoglossus m., by CN X)
This test is used for?
Patient protrudes the tongue, press left and reight on the cheek against the tester’s finger pressure and make fast movements by saying “la la la”
To test the hypoglossal nerve
When is unilateral hypoglossal weakness more evident?
During tongue protrusion
the tongue deviates to the weak side
Branchiomotor cranial nerves include
V, VII, IX, X, XI
Mixed nerves each with one or more sensory ganglia
WHat is the embryonic origin of CN V, VII, IX, and X?
- 1st arch mesoderm: muscles of mastication, anterior digastric and 2 tensors, innervated by mandibular division of N. V
- 2nd arch mesoderm: the muscles of facial expression and the more ancient posterior digastric and stylohyoid muscles, innervated by N. VII
- 3rd and 4th arch mesoderm: stylopharyngeus, Lev. Palati, pharyngeal constrictors and other muscles innervated by N. IX and X
Which nerve is known as the grat mover of the jaw and sensor of the face?
FACIAL NERVE
What are the 3 divisions of the facial nerve?
Opthalmic V1 (senesory)
Maxillary -V2 (sensory)
Mandibular V3 (sensory and motor)
Wheer do the roots of the trigeminal nerve emerge from?
Exits lateral surface of pons by passing through the middle cerebellar peduncle
Motor root is largely separate and joins mandibular division
Trigeminal Senory Ganglion
(semilunar of Gasserian)
Is plastered onto the floor of the middle cranial fossa by dura
(MASSIVE)
- The ophthalmic division (V1 ) passes through the superior orbital fissure into the orbit, accompanied by cranial nerves III, IV and VI
- The maxillary division (V2) passes through the foramen rotundum into the pterygopalatine fossa
- The mandibular division (V3) passes through the foramen ovale into the infratemporal fossa
What is the funciton of the Sensory fibers for CN V?
Convey touch, pain, and temperature from skin on face and the cranial meningies
Lining and content of the major cranial cavities
V1: orbit & upper 1/2 of nasal cavity
V2: lower 1/2 of nasal cavity upper 1/2 of oral cavity
V3: lower 1/2 of oral cavity
Trigeminal motor nucleus
a large branchiomotor nucleus in the rostral pons innervating the following 1starch muscles:
temporalis, masseter, medial & lateral pterygoids, anterior digastric, mylohyoid, tensor tympani and tensor veli palatini.
TRigeminal Sensory nuclei
Principle Trigeminal Sensory Nucleus
-in rostral pons, mainly serving touch
Nucleus of the Trigeminal Spinal Tract
- extends through caudal pons & medulla
- mainly serving temperature and pain
Mesencephalic Trigeminal Nucleus
- centrally located, peripherally projecting sensory neurons! Very Unique!
- in caudal midbrain & rostral pons
- mainly serving proprioception from muscles of mastication and teeth
Trigeminal nerve is involved in which reflex?
The jaw jerk reflex (involve Vmes and Vmot)
Corneal Relfex
How is the JAw jerk reflex tested?
by a gentle hammer tap which activates proprioceptors in the jaw muscles
What is the corneal reflex?
involving sensory fibers of V1, relay neurons in the main V sensory nucleus and facial nerve motoneurons innervating the orbicularis oculi is tested by a gentle touch to the cornea
Hitchhiking PS Pathways
(CN V)
Although the Trigeminal Nerve has no visceral motor components, that is, no preganglionic nucleus or fibers…..
…..most of the post ganglionic parasympathetic fibers in the head travel along branches of the Trigeminal Nerve
This nerve is related to 1st pharyngeatl pouch and Hyoid arch
Vacial Nerve (CN VII)
Intamately involved in the middle ear
What is the direction of the facial nerve?
- roots emerge at pontomedullary junction
- comprises a larger motor root and a smaller nervusintermedius which carries sensory and visceromotor fibers
- enters temporal bone at internal acoustic meatus
WHat are the functional efferent components of the Facial nerve?
Efferent
branchiomotor to hyoid arch muscles (SVE)
- muscles of facial expression, stylohyoid, posterior digastic, stapedius (Central Nucleus - VII motor nucleus )
Secretomotor (parasympathetic) to ptergopalatine and submandibular ganglia (SVE) (Central Nucles - Suprior Salivatory nucleus)
What are the functions Afferent components of the facial nerve?
Geniculate Ganglionin temporal bone
- majorgustatorycomponent; innervates taste buds on palate and anterior 2/3 of tongue (SVA) (Project ro Nuc Sal Tract)
- smaller touch and pain component (GSA) (Projects to Nuc Vsp Tract)
What are the 3 major nerves that arise from the temporal bone?
Facial nerve
Greater petrosal nerve
Chorda Tympani
What is the function of the facial nerve?
Mainly motor to muscles of facial expression, stylohyoid & posterior digastric
(exites stylomastoid foramen and give off branches to the side of the face and a small branch to the stapedius muscle)
What is the function of the greater petrosal?
PS: pterygopalatine ganglion to lacrimal gland and small mucous glands of palate and nasopharynx
Distributed on branches of V2& V1
What is the function of the chorda tympani?
Joins the lingual branch of V3
Tastefrom anterior 2/3 of tongue
PS: submandibular ganglion to submand. & sublingual glands
(goes to lingual and submandibular region - gustatory and PS)
How do you test CN VII?
Sweet , sour, salty, and funny faces
What is the relationship of structures that transverse the jugular foramen?
CN IX, CN X, and CN XI are in numerical order, anterior to the internal jugular vein as they transverse the foramen. They are immediately posterior to the internal carotid artery as they emerge from it. The superior and inferior sensory ganglia of CN IX and CN X are see as thickning of those nerves immediately inferior to thei exit from the cranium
Which nerve is a Branchial nerve related to 2nd pharyngeal pouch (tonsilarfossa between stylohyoid ligament and middle constrictor)and 3rd Arch (think about the greater horn of the hyoid bone)?
CN IX - Glossopharyngeal
What is the direction of CN IX?
- roots emerge at rostral medulla, dorsal to anterior end of inferior olive and in line with adjacent vagusroots
- then they enters jugular foramen with Xth and XIth nerves
- gives off tympanic nerve into the temporal bone, which then emerges from the bone as the lesser petrosal nerve
- The nerve exits jugular foramen at base of skull
What are the funtional efferent components of the Glossophayngeal nerve?
–branchiomotor to 3rd arch muscle (stylopharyngeus)(SVE)
(Central Nucleus-rostral pole of nucleus ambiguus(SVE))
-secretomotor control of parotid gland by parasympathetic (GVE) fibers to oticganglion(GVE) via lesser petrosal nerve
(Central Nucleus -Inferior Salivatory nucleus (GVE))
What are the afferent components of the Glossopharyngeal nerve?
- superior and inferior ganglia
- taste from posterior 1/3 of tongue (SVA) and sensory from carotid body and sinus (GVA)
(Project to - Nuc Sol Tract (SVA and GVA))
- touch and pain from middle ear, tonsils, back of soft palate, posterior 1/3 of tingue and pharynx
(Project to - Nuc Vsp Tract (GSA))
Which nerve is know as the Wanderer?
CN X
VAGUS NERVE
What are the afferent components of CNX?
- superior(jugular) and inferior (nodose) ganglia
- Major sensory inputs from cervical, thoracic and abdominal viscera (GVA) and minor taste input from epiglottic region (SVA)
(Nuc Sol Tract (GVA & SVA))
-touch and pain from ear canal, auricle & meninges (GSA)
(Nuc Vsp Tract (GSA))
What are the efferent components of CN X?
-motor to 4th-6tharch muscles (SVE= branchiomotor) and more properly, motor to striated muscles of pharynx, larynx and soft palate
(nucleus ambiguus (SVE, mostly))
-Preganglionic parasympathetic (GVE) to all visceral structures from neck to upper hindgut
(dorsal vagal motor nucleus (GVE, mostly))
Describe the Vagus Nerve Pharyngeal distribution. What are the different branches motor and sensory?
- Superior auricular branch - sensory to back of ear
- Meningeal branch - sensory to dura in posterior cranial fossa
- Pharyngeal branch - motot to palatal muscles and pharyngeal constrictors and sensory from epiglottis, upper pharynx and possible aspects of soft palate
- Superior laryngeal branch - sensory from upper part of larynx and motor to cricothyroid m.
- Recurrent laryngeal branch - motor to all other laryngeal mm and to constricto and esophagous + sensory from lower larynx, upp esophagous
Describe the vagus distribution to thoracic and abdominal viscera
- Visceromotor fibers (GVE) from the Dorsal Motor Nucleus of the Vagus target parasympathetic ganglia in the heart, lungs, kidneys and abdominal viscera, as far down as the beginning of the descending colon.
- Afferent fibers (GVA) from the Vagal Sensory Ganglia (especially the inferior) bring information back to the brain from all of the organs that receive vagal efferents.
These Vagal visceral sensory fibers (GVA) terminate in the Nucleus of the Solitary Tract in the medulla.
Parasympathetic regulation the heart, lungs and all derivatives of the embryonic fore- and hind-gut, as well as the kidneys are recieved from which nerve?
Vagus Nerve
How is Cardiovascular function controlled? Which nerves are involved?
This control is Autonomic
Sensory signals pertaining to arterial pressure (CN IX) and blood oxygenation (CNX) are relayed to the nucleus of the solitary tract, which in turn organizes autonomic outflow via interneurons in the medullary reticular formation. This circuit provides negative feedback to visceral motor neurons that govern cardiovascular function.
LOOK AT PICTURE FOR MORE UNDERSTANDING
How do you test the function of CN IX?
Say AHHHHH
The gag reflex (IX), palatal elevation and vocal cord position during phonation can be readily tested (Gental touch to the pharyngeal wall)
Problems with Nerve IX and X are most evident how?
Difficulty swallowing (palal and pharyngeal muscles) and Phonation (laryngeal mm.) Although many of the IX-X muscles cannot be directly examined, careful observation of swallowing and phonation can revealing.
Also, Painful neuralgia can arise from the IX-X innervated regions of the posterior tongue, pharynx, ear canal and external ear.
What is the function of the Spinal accesory nerve (CN XI)?
Provides motor innervation to SCM and Trapezius, particularly the superior part of the latter.
XI has no permanent sensory ganglia.
Where is the motor nucleus for CN XI located?
In the cervical spinal cord from C1-C6
What is the direction of CN XI?
Roots exit laterally, they are neither ventral nor dorsal. The roots continue directly in line with the caudal vagal motor roots.
XI axons form an ascending bundle within the duralsac, enter the skull through the foramen magnum and join with caudal vagal fibers to leave the skull via the jugular foramen.
Deficits in contralateral head turn and weakness in should elevation and rotation is caused by what?
Lesion of XI
Contralateral head turn = SCM
Shoulder = Trapezius
There are two nerves that join together so that they run together, which are they and describe them?
Vagus (X) and Spinal accessory (XI) nerve
LOOK AT IMAGE
Summary of Cranial Nerve Eferent and Afferent Nucleei
Summary of Cranial Parasympathetic pathways
Somatopleure
More or less a combination of everything produced from the somites, as well as the outer layer of the lateral plates mesoderm that integrates with the ectoderm to form the outer body wall
Where are cell bodies for sensory neurons found in the cranial region? In the spinal region?
Cranial region: The cell bodies are found in the sensory ganglions associated with specific cranial nerves
Spinal region: Cell bodies are going to be in the dorsal root ganglion
CN I
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Olfactory
Type: Sensory
Central nuclei: Olfactory Bulb
Targets: Olfactory neurons
Function: Smell
Skull: Cribiform plate
Brain: Telencephalon
Smell
Cribriform plate
Telencephalon
CN II
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Optic
Type: Sensory
Central Nuclei: Lateral geniculate nucleus
Targets: Retina
Function: Sight
Skull: Optic foramen
Brain: Retinal ganglion cells
CN VIII
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Vestibulocochlear
Type: Sensory
Central Nuclei:
- Vestibular n.
Efferent
Vestibular efferent nuclei
Afferent
Vestibular nuclei (superior, medial, lateral, and descending)
- Cochlear n.
Efferent
Superior olivary/periolivary nuclei
Afferent
Dorsal & ventral cochlear nuclei
Targets:
Cochlear :
- Auditory hair cells of spiral organ
Vestibular:
- Ampullae of semicircular canals
- Maculae of the saccular and utricular otoliths
Function: Hearing and balance
Skull: Internal auditory canal
Brain: Lateral to CN VII (ponomedullary junction)
CN III
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Oculomotor
Type: Motor
Central Nuclei:
- Visceral
Edinger-Westphal Nucleus
- Somatic
Oculomotor nucleus
Targets: Levator palpebrae superiors muscle
Function: Innervation to 4/6 eye movement muscles + levator palpebrae superioris, pupil constriction, curvature of lens
Skull: superior orbital fissure
Brain: superior orbital fissure
CN IV
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Trochlear
Type: Motor
Central Nuclei: Trochlear nuclei
Targets: Superior oblique muscle
Function: Eye abduction, depression, internal rotation
Skull: superior orbital fissure
Brain: Dorsal aspect of Midbrain
CN VI
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Abducens
Type: Motor
Central Nuclei: Nucleus of abducent n.
Targets: Lateral rectus muscle
Function: Eye abduction
Skull: superior orbital fissure
Brain:
- Nuclei lying under the floor of the fourth ventricle
- Pons
CN XII
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Hypoglossal
Type: Motor
Central Nuclei: Hypoglossal motor nucleus
Targets: Muscles of the tongue
Function: Motor to tongue muscles (all the “glossus” muscles EXCEPT palatoglossus)
Skull: Jugular foramen
Brain: Medulla
CN V
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Trigeminal
Type: Both
Central Nuclei:
- Motor
Trigeminal motor nucleus
- Somatic
Principle trigeminal sensory nucleus, nucleus of the trigeminal spinal tract, mesencephalic trigeminal nucleus
Targets: Muscles of the jaw, mouth, and inner ear
Function:
V1 – sensory from upper face and most of dura mater
V2 –sensory from middle face and dura mater around sphenoid bone
V3 – sensory lower face, dura mater by temporal bone AND motor to muscles of mastication, ant belly digastric, mylohyoid, tensor veli palatine, tensor tympani
Skull
V1 – sensory from upper face and most of dura mater
V2 –sensory from middle face and dura mater around sphenoid bone
V3 – sensory lower face, dura mater by temporal bone AND motor to muscles of mastication, ant belly digastric, mylohyoid, tensor veli palatine, tensor tympani
Brain: Pons
CN VII
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Facial
Type: Both
Central Nuclei:
- Muscle motor – Facial motor nucleus
- Secretion – superior salivatory nucleus
- Taste – Nucleus of the solitary tract
- Somatic sensation – nucleus Trigeminal spinal tract
Targets
- Hyoid arch muscles
- Pterygopalatine and submandibular ganglia
- Taste buds
Function: Muscles of facial expression, taste from anterior 2/3 tongue, salivary (except parotid) and lacrimal glands, sensation on ear
Skull: stylomastoid foramen
Brain:
Pons
(ponomedullary junction) above olive
CN IX
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Glossopharyngeal
Type: Both
Central Nuclei
- Motor – Rostral pole of nucleus ambiguus
- Secretion – inferior salivatory nucleus
- Taste & pCO2 – nucleus of solitary tract
- Somatic sensation – Nucleus of trigeminal spine tract
Targets
- Base of tongue
- Pharynx
- The birfucation of the common carotid artery
Function
- Taste to post 1/3 tongue, sensory to sinuses, oropharynx, middle ear cavity
- Motor to stylopharyngeus m, parotid gland
Skull: jugular foramen
Brain: Medulla
CN X
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Vagus
Type: Both
Central Nuclei
- Parasympathetics-
Dorsal nucleus of vagus nerve
- Branchiomotor- nucleus ambiguous
- Visceral afferents- solitary nucleus
- Sensation- spinal trigeminal nucleus
Targets:
- Pharynx
- Larynx
- Soft palate
- Visceral structures from neck to upper hindgut
Function
- Taste in root of tongue, sensation of inside of ear canal, pharynx, larynx, trachea, bronchioles, lungs, heart, GI (up to left colic flexure)
- Motor to throat muscles, trachea, bronchioles, heart, GI (up to left colic flexure)
Skull: Jugular foramen
Brain: Posterolateral sulcus of Medulla
CN XI
Name
Type
Central Nuclei
Targets
Function
Skull
Brain
Name: Accessory
Type: Special motor
Central Nuclei: Nucleus of spinal accessory nerve
Targets:
- SCM
- TRAPEZIUS
Function: Motor to SCM and trapezius
Skull: Jugular foramen
Brain: Cranial and Spinal Roots
What is visceral innervation?
The innervation of the inner layer of the lateral plate mesoderm, which wraps around the endoderm to form the splachnopleure
What is the somatopleure?
It is more or less combination of everything produced from the somites, as well as the outer layer of the lateral plate mesoderm that integrates with the ectoderm to form the outer body wall.
True or false. Visceral innervation requires another neuron.
True
*Visceral neurons cannot project al the way to a gland. They project out to peripheral autonomic ganglia, which is either sympathetic or parasympathetic.
True or false. Cranial nerves have their own sympathetic outflow.
False
*ALL sympathetics come to the head from below.
What is a neurogenic placode?
A patch where the cells elongate and differentiate and develop to form this community where the cells start to form the neurons of the special sense organs
The olfactory bulb is part of the __________ and the olfactory trac is just a tract.
Forebrain
What type of nucleus is the lateral geniculate nuclei of the thalamus?
Diencephalic nucleus
When neural fibers cross the midline from one side to another that’s called ___________.
Decussation
*The optic chiasma half of the fibers of the optic tract decussate
The large interneurons of the retina, which form the output elements are called _________.
Retinoganglionic cells
*Their axons are what makes up most of the optic nerves and the majority of them project back into the brain and synapse in the lateral geniculate nucleus
Why can you end up with visual problems when there is a change in CSF pressure?
The optic nerve is surrounded by meninges. All of the layers of the meninges surround the optic nerve and continue on to the eye ball.
*Often visual disturbances are one of the earliest signs of increases in CSF pressure
The hair cells of the ampulla of the semicircular canal are sensitive to which types of movement?
Rotation of the head
What is the function of spiral ganglia?
Spiral ganglion is a group of nerve cells that serve the sense of hearing by sending a representation of sound from the cochlea to the brain
A ganglion cell in the cochlea is known as the ________; however, the whole structure is called the __________.
Spiral ganglion; Organ of Corti
What’s the importance of the vestibulocochlear nerve having efferents and not just afferents?
To be a good sense organ you must hvae efferent fibers so the brain caould modulate the sensitivity and other characterisitcs of the sense organ.
*it modifies what you listen to.
Only cranial nerve that exits from the dorsal side of the cranium
Trochlear nerve
The only branch of the trigeminal to carry motor innervation.
Mandibular
