Cranial nerve nuclei Flashcards
CN 1 nuclei
no nuclei
Olfactory nerve to bulb, mitral cells, to olfactory tract, to periamygaloid cortex/entorhinal cortex.
CN 2 nuclei
No nuclei
Retina, retinal ganglion cells, lateral geniculate, V1
Nasal half of retinal ganglion cells cross to contralateral optic tract at the optic chiasm. BUTTT note that these ganglion cells are actually VIEWING the Temporal feild of vision.
Other firbers of the optic tract Pass the lateral geniculate and go to the
Prectectal Nucleus –> pupillary light reflex aka direct and consensual light reflexes.
Superior Colliculus –> Saccades
Regulate optic reflexes.
CN 3 nuclei
Main motor nucleus of oculomotor nerve. GSE
innervates:
- Superior Palpebral muscle
- Superior Rectus muscle
- Medial Rectus muscle
- Inferior Rectus
- Inferior Oblique muscle
Eddinger-Westphal nucleus, aka Accessory parasympathetic nucleus of the oculomotor nerve.
GVE, short cilliary nerves
CN 4 nuclei
Trochlear nucleus, at level of inferior colliculus, GSE
CN 5 nuclei
Chief Sensory nucleus -> epicritic sensory information from the head/face
turns into -
Spinal trigeminal nucles - protopathic sensory information from the head/face
Dorsal trigeminal nucleus = mesencephalic trigeminal nucleus. In the midbrain.
- Proprioceptive information from muscle spindles in the masticatory muscles/tendon organs. Only place in the CNS having pseudounipolar neurons.
Form reflex loops for the face muscles
Motor nucleus-
Medial to the main sensory nucleus, at level of medial eminence in pons.
CN 6 nuclei
Abducens nucleus,
at pontomedullary junction -GSE
CN 7 nuclei
1) Main motor nucleus - SVE
motor innervation to the facial muslces
The motor neurons innervating the Upper half of the face recieve Bilateral innervation.
The motor neurons innervating the Lower half of the face recieve only Contralateral innervation from the motor cortex.
So, Central lesion –> contralateral lower half of face is paralyzed
Peripheral lesion –> whole half of face is paralyzed.
2) Superior Salivatory nucleus - GVE preganglionic parasympathetic - courses with chorda typmani to reach the submandibular ganglion, which then sends postganglionic fibers to the submandibular and usblingual glands.
3) Lacrimal nucleus - GVE (lacrimal nucleus is a subset of cells within the superior salivatory nucleus, physically in the same part of the brain stem.)
Courses with the greater petrosal nerve to stimulate postganglionic cells in the pterygopalatine ganglion, which then sends fibers to course with the opthalmic nerve of trigeminal, to the lacrimal nerve to reach the lacrimal gland. .
4) Nucleus of the Solitary tract - a common nucleus recieving afferent fibers from several nerves
- Receives taste information from the Nervus Intermedius, which are the afferent fibers of pseudounipolar taste sensory cells in the Geniculate Ganglion, which give off the nerve fibers of Chorda Tympani peripherally.
CN 8 nuclei Vestibular group
4 Vestibular nuclei: Superior, Inferior, Medial, and Lateral
Lateral vestibular nucleu = Dieter’s Vestibular nucleus, gives lateral vestibulospinal tract.
Afferent:
1) From the Vestibular Ganglion, which extends fibers into the Maculae of the Utricle and Saccule (ipsilaterally). Synapse primarily on Medial Vestibular Nucleus.
2) From the Fastigial Nucleus (bilaterally) via inferior cerebellar peduncle.
Efferents:
1) Vestibulocerebellar tract via Inf Cereb Peduncle
2) Vestibulospinal tract, ipsilaterally, lateral and medial vestibulospinal tracts from Dieters nucleus and medial vestibular nucleus.
3) From the Lateral Vestibular nucleus specifically –> Fibers into the Medial Longitudinal Fasciculus to the Visual system Cranial motor nuclei. (Occulomotor, Trochlear, and Abducens)
CN 8 Cochlear Nuclei
The Anterior Cochlear Nucleus
and
The Posterior Cochlear Nucleus
Afferents:
From the Spiral Ganglion of the cochlea.
Efferents:
Send axons, decussating in the trapezoid body to the Superior Olivary Nucleus/ Superior Olivary Complex which includes nuclei that may be in the trapezoid body.
From the Superior Olivary Nucleus –> bilaterally to the lateral lemniscus,
From Lateral lemniscus fibers go to several places
1) Nuclei of the lateral lemniscus
2) Inferior Colliculus
3) Medial geniculate body –> Primary Auditory Cortex. (via acoustic radiations near internal capsule)
CN 9 nuclei
1) Main motor nucleus of Glossopharyngeal = the Superior Tip of Nucleus Ambiguus.
- -> bilateral innervation from cortex, innervates the stylopharyngeus muscle. SVE
2) Inferior Salivatory nucleus = Parasympathetic nucleus of Glossopharyngeal
- is at the level of the inferior olivary nucleus and both of the two other glossopharyngeal nuclei.
Inferior Salivatory nucleus –> Tympanic nerve and tympanic plexus –> Otic ganglion –> postganglionic fibers to the Parotid Gland, coursing with Facial nerve.
3) Nucleus of Solitary Tract
GVA and SVA afferents
-Recieves Baroreceptor fibers from the Herrings nerve,
-Recieves Taste sensation from posterior 1/3 of tongue AND from the Circumvallate Papillae
-Cell bodies for both of these afferents are in the Inferior/Petrosal ganglion.
4) Spinal Trigeminal nucleus
- Fibers that course with the Glossopharyngeal nerve provide GSA innervation to the posterior third of tongue, pharyngeal mucosa, and tympanic cavity,
- The cell bodies are in the Superior Ganglion of glosspharyngeal.
CN 10 nuclei
1) Middle portion of Nucleus Ambiguus = Main motor nucleus of Vagus (SVE)
- Bilaterally innervated by cortex –> Innervates pharyngeal constrictors and intrinsic muscles of layrnx.
2) Dorsal nucleus of Vagus = The nucleus under Ala Cinerea = The parasympathetic nucleus of Vagus
Recieves GVA and sends GVE
-Carotid regulation
-Pulmonary regulation
-GI tract Visceral regulation as far as the Canon-Bohm point (pelvic splanchnic nerves after that)
3) Nucleus of Solitary Tract SVA and GVA, Recieves afferent fibers from cell bodies in the Inferior vagus ganglion/Nodose ganglion.
- Recieves Taste Afferent SVA fibers from Epiglottis, cell bodies in the inferior Ganglion of Vagus nerve. –> on to Ventral group of nuclei in thalamus –> relayed to primary gustatory area
- GVA fibers from all of the organ and internal mucosa
4) Spinal Trigeminal nucleus recieves GSA fibers from:
- Posterior cranial fossa
- External acoustic meatus via Auricular branch of vagus
- Cell bodies lie in the Superior ganglion of vagus
CN 11 nuclei
1) Nucleus Ambiguus, Inferior portion –> Cranial root of the accessory nerve, May assist Vagus nerve motor innervation of Pharynx and interinsic laryngeal muscles.
May or may not actually exist, newer evidence suggests not.
2) Spinal nucleus of accessory nerve. Accessory Nucleus
- Strictly a SVE nerve
Innervates Trapezius and Sternocleidomastiod (pharyngeal arch derived SVE efferent)
CN 12 nuclei
1) Hypoglossal nucleus- purely a motor nucleus and nerve
- GENERAL somatic efferent motor innervation of all of the intrinsic tongue muscles
- also to Styloglossus, Hyoglossus, and Genioglossus
What are the only SVE nuclei
SVE- Special visceral efferent.
For muscles derived from pharyngeal arches and their associated cranial nerves.
Mandibular division of the Trigeminal -> Main motor nucleus of trigeminal -> mastication muscles, tensor veli palatini, tensor tympani, anterior belly of digastric
Facial motor nerves -> Facial motor nucleus
Glossopharyngeal -> Stylopharyngeus muscle
Vagus –> Motor innervation of the pharyngeal constrictor muscles and the intrinsic muscle of larynx.
Accessory motor nucleus –> Motor output Sternocleidomastoid and Trapezius.
Simplified CN 9 nuclei
Solitary nucleus: Taste from the posterior one-third of the tongue and information from carotid baroreceptors and carotid body chemoreceptors
Spinal nucleus of the trigeminal nerve: Somatic sensory fibers from the middle ear
Lateral Nucleus of Ala Cinerea: Visceral pain
Nucleus ambiguus: The lower motor neurons for the stylopharyngeus muscle
Inferior salivatory nucleus: Parasympathetic input to the parotid and mucous glands.
