The larynx Flashcards
What do the extrinsic laryngeal muscles do?
2 types - infrahyoid muscles (below hyoid bone) and suprahyoid bone (above hyoid). they are attached to the hyoid bone which is attached to ligaments that allow the whole of the larynx to be moved as a whole.
SHM elevate the larynx
IFM depress the larynx.
If you want to swallow the SHM will pull H up - close to the epiglottis making a nice tight seal.
SHM, IFM help to stabilise the Larynx.
What do the internal laryngeal muscles do?
Control the shape of the rima elottidis (space between vocal cords and arytenoid cartilages), the lenght of the vocal cords and their tension.
- Cricothyroid muscle - stretches and tenses vocal ligaments.
- Contracts, rotates Thyroid cartilage forward. Increases tension in vocal cords and length increase. Higher pitch - Vocal cords closer together- MORE oscillation and vibration when air is forced past.
Thyroarytenoid M - relax vocal ligament (pulls thyroid cartilage back into position , lowering pitch - shorter vocal cords, less tension.
What is Phonation?
The creation of sound from the vibration of the vocal folds against each other.
What happens during whispering?
During whispering transverse arytenoid is not activated , so there is a little gap btw vocal cords - more air passes through, less vibration if VC.
Transverse arytenoid usually adducts (move towards midline) arytenoid cartilage - closing rima glottidis)
What muscles are involved in controlling the shape of the laryngeal inlet and rima glottidis?
POSTERIOR CRICOARYTENOID - sole abductors (move away from midline) of the vocal cords - widen rima glottidis.
LATERAL CRICOARYTENOID - adductors (towards midline) of vocal cords - narrow rima glottidis.
TRANSVERSE AND OBLIQUE ARYTENOID - adducts arytenoid cartilages - closes posterior portion of the glottidis - narrows laryngeal inlet.
How are Laryngeal muscles involved in the cough/sneeze reflex?
Cough - forced expiration against a closed glottis , which opens suddenly with charchteristic sound and explusion of secretions and foreign materials from respiratoty tract.
Background - diaphragm / external intercostal muscles contract(increasing intrathoracic volume, intrathoracic pressure drops, air rushes in to equalise pressure. )
- Rima glottidis/Glottis closes and vocal cords contract - close larynx. (caused by cricoaryetenoid M)
- Abdominal muscles contact, diaphragm relaxes and the other expiratory muscles - Internal/innermost ICM contract. (volume of thorax decreases, pressure increases)
- Vocal cords relax , rima glottidis opens, releasing air out at over 100mph.
What does the recurrent laryngeal nerve do?
Innervates all of the intrinsic muscles of the larynx except for the cricothyroid muscle.
- Origin- Branch of the vagus nerve ,
- Route-
- route- (left nerve) curves inferior around the aortic arch , then ascends in the groove btw the oesophagus and trachea.
- Route -(right courses around the right subclavian artery, wind inferiorly around the nerve, then posteriorly to vessel, then obliquely (diagonal)posterior to the common carotid artery. .
What the superior laryngeal nerves do?
2 branches
Origin - the vagus nerve
- external branch - supplies Cricothyroid gland which controls speech.
- internal branch- supplies sensory fibres/sensation to part of the larynx (mucosa to epiglottis to just above vocal cords)
What is the consequence of injury to the recurrent laryngeal nerve?
Recurrent laryngeal nerve runs close to the apex of the lung. If damaged , the intrinsic laryngeal muscles will be paralysed apart from the cricothyroid M.
Can be caused by Apical (related to apex) tumour which erodes and damages the nerve.
Which muscles have the most control over the vocal cords?
Internal/ innermost ICM not diaphragm. Diaphragm has fewer motor units per surface area.
What is the Pharynx composed of ?
Nasopharynx
Oropharynx
Laryngopharynx
