Cranial Nerves - Lecture 2 Flashcards
What is cranial nerve VII?
Facial nerve
What does CN VII innervate?
Innervates the muscles of facial expression (motor)
Innervates the orbicularis Oculi muscle
(frequently monitored during surgery around the face)
What are surgery where the facial nerve is monitored?
Parotidectomy, acoustic neuroma, cochlear implants
What is cranial nerve IX?
Glossopharyngeal
What does CN IX innervate? (4)
Sensory innervation to the baroreceptors of the carotid sinus
Sensory innervation to the chemoreceptors of the carotid body
Sensory innervation of the posterior oral mucosa (gag reflex)
Motor innervation of the pharynx (swallowing)
What happens if CN IX is innervated during a CEA?
Can cause bradycardia and hypotension
What CN does the SLN & RLN come off of?
Vagus Nerve (CN X)
What is the internal and external branch of the SLN
Internal branch –> sensory
External branch –> motor, cricothyroid muscles
When might injury to the SLN and RLN occur?
during thyroid surgery
In the external branch of the SLN, what does the cricothyroid muscles do?
Tense and adduct the vocal cords
Injury to the SLN will usually cause changes in what?
voice quality - usually not dangerous
What is worse, injury to the RLN or SLN? and why
RLN - it innervates all of the intrinsic muscles of the larynx except for the cricothyroid
What happens with unilateral RLN injury?
produces abductor vocal cord paralysis (posterior cricothyroid muscle), so the affected cord assumes a paramedian position which causes postop hoarseness
How does BL vocal cord paralysis manifest?
Partial VS complete airway obstruction.
Symptoms include respiratory distress vs stridor
If a patient has BL vocal cord paralysis, what often needs to happen?
Emergent reintubation or trach
What does the vagus nerve stimulation on the heart do?
Vagal stimulation reduces HR and is constantly active
Cardiac branches convey parasympathetic innervation to the ____ and ____ nodes of the heart
sinoatrial and atrioventricular
CN X in the lungs: Parasympathetic stimulation within the pulmonary plexuses cause
vasodilation and bronchoconstriction
T/F: The vagus nerve provides parasympathetic innervation to the majority of abdominal organs
True
What is the function of the vagus nerve in the GI system?
To stimulate smooth muscle contraction and glandular secretions in these organs
What can happen with vagal stimulation during GO surgery?
significant bradycardia, even asystole
