Nerve Supply Of Larynx And Vocal Cord Palsy Flashcards
Which nerve supplies the larynx ?
Vagus nerve ; vagus nerve emerges through the jugular foramen along with the 9 , 10 ,11 cranial nerves
How many ganglia does the vagus nerve have ?
Two
They are the
Superior ganglion of vagus
Inferior ganglion of vagus
What are the branches of the superior ganglion of vagus ?
Arnold nerve : auricular branch of the vagus that supplies the Pinna
Pharyngeal branch : this along with the 9th nerve and sympathetic chain forms the pharyngeal plexus
What is the nerve arising from the inferior ganglion of vagus ?
Superior laryngeal nerve (SLN)
At what level does the superior laryngeal nerve divides into two branches ?
At the level of HYOID , SLN divides into INTERNAL LARYNGEAL NERVE and EXTERNAL LARYNGEAL NERVE
Internal laryngeal nerve supplies what ?
Internal laryngeal nerve gives sensory supply to the upper part of hypopharynx and the supra glottis after piercing the thyrohyoid membrane just above the upper border of inferior constrictor muscle
Injury to internal laryngeal nerve causes what ?
Repeated aspiration of foreign body as sensation to sense this aspiration is lost
What does the external laryngeal nerve supply ?
It supplies the only intrinsic muscle that lies externally i.e CRICOTHYROID (tensor of the vocal cords )
External laryngeal nerve accompanies SUPERIOR THYROID VESSELS
How does the recurrent laryngeal nerve enters the larynx ?
This nerve enters the larynx between the inferior constrictor and the oesophagus behind the cricothryoid joint after running through the tracheo-oesophageal groove
Left RLN arises from where ?
Arises from the level of ARCH OF AORTA and has a longer course than the right RLN hence more prone to injury
From where does the right RLN arises ?
It arises from the level of subclavian artery ; has a shorter course than left RLN
RLN enters the larynx with the inferior thyroid vessels
Supply of RLN ?
Sensory supply - glottis and subglottis
Motor supply - to all the muscles of larynx except cricothyroid
What is cardiovocal syndrome / ortner’s syndrome ?
It is the compression of left RLN by enlarged left atrium
Left RLN is more prone to injury at the mediastenum while right RLN is more prone to injury at the level of neck
What are the nerves that are injured in base of skull injury ?
Palsy of whole vagus can occur including the pharyngeal branches and at the same time other cranial nerves can also be involved
Involvement of pharyngeal branches leads to dysphagia,regurgitation
Nerve injury that is associated with carotid triangle surgery ?
SLN , ILN , ELN since carotid triangle is at the level of hyoid
Nerve injury that is associated with cervical spine surgeries
RLN
What is otner’s syndrome ?
Mitral stenosis causing dilatation of left atrium leading to left RLN compression
When will the position of the vocal cord will be in midline ?
Phonation
When will the position of the vocal cord will be in midline ?
Phonation
Position of vocal cord during whispering ?
Paramedian - 1.5mm away from the midline
Position of vocal cord in complete palsy?
Intermediate / cadaveric position - 3.5mm away from the midline
Normal respiration position of vocal cords ?
Slight abduction - 7mm from the midline
Position of vocal cords in forced respiration ?
9.5mm away from the midline - full abduction
Position of vocal cord in adductor palsy / complete palsy / SLN + RLN palsy
Cadaveric / intermediate position
This is called as adductor palsy as the person is not able to adduct the vocal cords
Position of vocal cord in incomplete palsy / RLN palsy / abductor palsy
Median / para median according to Wagner and gross man theory
What is Wagner and grossman theory ?
In RLN palsy all the muscles will be affected except for cricothyroid keeping the vocal cords adducted i.e median / paramedian position
Treatment for bilateral RLN palsy
Tracheostomy with lateralisation of one vocal cord as the patient will have stridor due to adduction of vocal cords
Treatment for unilateral adductor palsy
Medialisation of vocal cord in order to correct aphonia
Treatment for bilateral adductor palsy
Tracheostomy with epiglottopexy
Here voice cannot be restored only the aspiration will be prevented
Paralysis of ELN palsy
Vocal cord can’t be tensed hence the voice will be low pitched
Vocal cord position : skewed / bowed
Most common cause of unilateral and bilateral recurrent laryngeal nerve injury
Thyroid surgery
Maximum stridor is seen in
Bilateral RLN palsy / bilateral incomplete palsy
How can we medialise the vocal cords in the unilateral complete palsy ?
Inject collagen , silicone , fat , calcium hydroxyapatite , Teflon laterally
Teflon is not recommended due to formation of granulation tissue
Lateralisation of vocal cords is done by
Cordectomy and arytenoidectomy : woodman’s procedure ; kashima’s procedure
Cordopexy : burning of a portion of vocal cords using laser
What is thyroplasty ?
Thyroid - framework surgery nothing to do with vocal cords
What are the types of thyroplasty ?
Proximalisation / medialisation - unilateral complete palsy - TYPE 1
Lateralisation - bilateral incomplete nerve palsy / bilateral RLN palsy -TYPE 2
Shortening - puberophonia / mutational falsetto - TYPE 3
Tightening / lengthening - androphonia - TYPE 4
