upper airway Flashcards
larynx: describe the laryngeal cartilages and how they are linked together by membranes, describe the intrinsic and extrinsic muscles and how they function during phonation, laryngeal closure, cough/sneeze reflexes and regulation of intra-thoracic pressure, describe the origin, course and functions of the nerve supply and functional consequences of nerve injury
principle function of larynx
prevent airway ingesting food (valve)
what condition may cause food to be asparated into the lungs, causing pneumonia
Parkinson’s disease
secondary function of larynx
sound producer
what 3 things is hollow larynx composed of
cartilages, membrane, muscles
bone between underside of mandible and thyroid cartilage
hyoid bone
shape and features of thyroid cartilage
two large flat cartilages joining at midline (similar to boat keel structure), with laryngeal prominence anterior
what is the cartilage below thyroid cartilage, and shape
cricoid cartilage, shaped like a signet ring (larger part posterior)
what is the gap between thyroid and cricoid cartilage, and clinical significance
cricothyroid membrane, where insertion of instrument to open airway in emergency (cricothyroidotomy)
significance of larger part of cricoid cartilage at posterior, forming cricothyroid joint
thyroid cartilage rocks backward and forward on it via medial surface of inferior thyroid horn into facet, partially altering tension on vocal folds (changing distance between anterior and posterior attachments)
effect of altering tension on vocal folds
change in pitch
what is below cricoid cartilage
tracheal rings
2 cartilages on top of epiglottis
arytenoid cartilages
shape and movement of arytenoid cartilages, and significance
small cones with large bases attached via facets, which swivel from side to side; attached to vocal folds, so when swivel (due to muscle contraction) they open or close the airway
what are vocal folds formed from
mucosal tissue draped over larynx and epiglottis
shape of mucosal tissue to form vocal folds (superior to inferior)
folded in (aryepiglottic fold) then folded out to form vestibule (vestibular fold), before folding back in again (vocal fold)
what ligament does vestibular fold mucosa overly
vestibular
what ligament does vocal fold mucosa overly
vocal
endoscopic view down throat (anterior to posterior) to form triangle
back of tongue, epiglottis, 2 pairs of lines (vestibular and vocal folds)
what is the opening between vocal folds called (middle of triangle) during breathing
rima glottidis
what muscles are involved in creating vocal sounds and moving vocal folds, changing tension
intrinsic muscles of larynx
anterior intrinsic muscle of larynx
cricothyroid muscle
what happens to thyroid cartilage when cricothyroid muscle shortens
rocks forward on cricothyroid joint, putting tension on vocal folds
4 muscles attached to arytenoid
transverse arytenoid, oblique arytenoid, posterior crico-arytenoid, lateral crico-arytenoid, vocalis muscle
function of transverse and oblique arytenoids
abduct and adduct vocal folds
function of posterior crico-arytenoid
swivel arytenoids to abduct and open up vocal folds and airway
function of lateral crico-arytenoid
swivel arytenoids to adduct and close vocal folds and airway
function of vocalis muscle (attaches directly to vocal ligament)
reduces tension on vocal folds
cranial nerve supplying larynx
vagus
branches of vagus nerve supplying larynx
superior laryngeal nerve, which branches to form internal and external laryngeal nerve; recurrent laryngeal nerve
significance of recurrent laryngeal nerve
as is also located very far away from larynx, changes in voice (e.g. hoarseness) can indicate issue elsewhere along recurrent laryngeal nerve pathway (e.g. left lung)
which recurrent laryngeal nerve is longer and why
left, as loops around ligamentum arteriosum (junction between aortic arch and pulmonary trunk), whereas right only loops around right subclavian artery
which branch of the superior laryngeal nerve has more involvement
internal
what does a lesion of the vagus before branching result in
complete paralysis (on one side)
what does a lesion of the internal laryngeal nerve result in
loss of sensation above vocal cords
what does a lesion of the external laryngeal nerve result in
paralysis of cricothyroid
what does a lesion of the recurrent laryngeal nerve result in
paralysis of all muscles of larynx except cricothyroid, and loss of sensation below vocal cords
what artery does superior laryngeal nerve (and branches) travel with
superior thyroid artery (first branch of external carotid artery)
what artery does recurrent laryngeal nerve travel with
inferior thyroid artery
examples of pathologies which left recurrent laryngeal nerve could be associated with
bronchial/oesophageal tumour, swollen mediastinal lymph nodes
4 protective mechanisms for airway
(protection during) swallowing, gag reflex, sneezing, coughing
nerve supplying afferent sensation of sneezing
V2
nerve supplying afferent sensation of coughing
X
common pathway of sneezing and coughing after afferent sensation
inspiration, raising intrathoracic pressure (glottis closed, abdominal muscles contracted)
what happens to soft palate when sneezing, what muscles cause this and what are they innervated by
depresses against tongue by palatopharyngeus and palatoglossus supplied by vagus
what happens to soft palate when coughing, what muscles cause this and what motor nerve(s) are they innervated by
raises and tenses against posterior wall of pharynx by levator veli palatini (X), tensor veli palatini (V3) and superior constrictor (X)
common pathway of sneezing and coughing after soft palate movement
sudden abduction of vocal folds to release intrathoracic pressure through nose and mouth
5 methods of intubation of airway
chin lift/jaw thrust, oropharyngeal or nasopharyngeal airway, endotracheal intubation, cricothyroidotomy, tracheostomy
