Branchiomeric CN Nuclei Flashcards
Brainstem nuclei organized in columns
Brainstem nuclei are named to 1 category*
(Nerves can be 3 or 4—easier to name the nucleus than the nerve)
GSE occupies most central area
GSA occupies most lateral area
Visceral occupy the area between
- Special Visceral aren’t really visceral, column occupies a ventrolateral area in brainstem
“SVE” nuclei will innervate skeletal muscle derived from pharyngeal arches
Motor Nucleus of V Muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini Facial Motor Nucleus Muscles of facial expression, stapedius Nucleus Ambiguus Upper esophagus, pharynx, larynx, stylopharyngeus Spinal Accessory Nucleus Trapezius and Sternocleidomastoid
Reflex pathways vs. voluntary movement
Reflex pathways of the SVE’s Jaw jerk Corneal blink Gag Mastication and Glutination
Voluntary pathways:
Corticobulbar
Jaw-jerk reflex.
UMN damage elicits a strong jaw-jerk, otherwise it is subtle
Gag and cough reflexes
gag- in by IX out by X
cough- in by X out by X
CN IX also involved in earlier swallowing, using stylopharyngeus
people with schizophrenia often don’t have a gag reflex
Activation of the upper esophagus from the nucleus ambiguus is
sequential and topographic
Mastication Networks
There is a central pattern generator (CPG) controlling rhythmic jaw movements between 3 Nuclei:
Motor Nucleus of V
Motor Nucleus of VII
Hypoglossal Nucleus
The “generator”/coordinator centers are in the reticular formation
Deglutition Networks
Involves both sensory feedback and motor control: 5 different cranial nerves involved 4 Afferents (CN V, VII, IX, X) 5 Efferents (CN V, VII, IX, X, XII) 4 Phases Oral Preparatory Phase Oral Transport Phase Pharyngeal Phase Esophageal Phase
Note: During a normal swallow, respiration must be temporarily halted, (deglutition apnea). Exhalation also typically occurs immediately before and after the swallow to prevent accidental inhalation of any bolus remnants.
Successful feeding also requires effective coughing and intact upper airway reflexes, which includes: gagging, vomiting, chewing
*Any kind of neurodegeneration that can effect any of these pathways can lead to DYSPHAGIA
Nerves, nuclei and their connections in the swallowing pathways
4 Afferents (CN V, VII, IX, X) Mesencephalic Nuc of V Main Sensory Nuc of V Semilunar Ganglion Nucleus of the Solitary Tract Inferior Ganglion of IX Inferior Ganglion of X
5 Efferents (CN V, VII, IX, X, XII) Motor Nuc of V Motor Nuc of VII Nucleus Ambiguus Hypoglossal Nuc
A CPG exists in the swallowing network too!
Controlled by Nucleus of the Solitary Tract and Nucleus Ambiguus
