Anatomy of larynx and vocal cord palsy

1. Anatomy
of the LARYNX
Dr.Anoop
JR 1 Anaesthesia
Max SS Hospital , Vaishali
Moderator – Dr prashant

2. Shape & Site
• A 2-inch-long, tube shaped organ.
• open into the laryngeal part of the pharynx
above and is continuous with the trachea
below
• It projects forwards in the median region of
the neck extending from the root of tongue
to the trachea

3. Function
• The larynx is the portion of the respiratory tract
containing the vocal cords
• The larynx functions in:
1. Deglutition (swallowing) protecting the trachea
against food aspiration
2. respiration (breathing)
3. Phonation (voice production) commonly called
the voice box

4. Relations
1. Anteriorly Skin, Fascia,
Infrahyoid m,
Pyramidal lobe
(if present)
2. On each side: Lat. Lobe of thyroid,
Carotid sheath.
3. Posteriorly: Pharynx

5. Structure of the larynx
The larynx is formed by a number of cartilages which are
connected by ligaments & membranes and lined by
mucous memb.

6. 1. Epiglottis
• It’s a leaf like lamella of elastic
cartilage
• It projects upwards behind the
tongue & the hyoid bone
• Its upper end is wide & free
• Its lower end is narrow & fixed
to the inner aspect of the
thyroid prominence

7. 2. Thyroid cartilage
• the largest of the nine cartilages that make up the
laryngeal skeleton.
• composed of two halves, which meet in the middle at
a peak called the laryngeal prominence, also called
the Adam's apple.
• In the midline above the prominence is the superior
thyroid notch. A counterpart notch at the bottom of
the cartilage is called the inferior thyroid notch.
• The post. Border of each lamina has 2 horns:
A- Sup. Horn: attached to the greater horn of hyoid
bone by the lat. Thyroid lig.
b- Inf. Horn: articulates with the cricoid cartilage at
the crico-thyroid joint.

8. 3.Cricoid cartilage
Below thyroid cartilage
• Ring shaped having a broad lamina
post. & narrow arch infront.
• The upper border of the lamina
articulates with the arytenoid
carilages.
• The post.lat. Aspect of the arch
articulates with the inf-horn of the
thyroid cartilage.
• Inferior to it are the rings of cartilage
around the trachea (which are not
continuous - rather they are C-shaped
with a gap posteriorly)

9. 4. Arytenoid cartilages
• Each one is pyramidal in shape having:
1. Apex: articulates with corniculate cartilage.
2. Base: articulates with cricoid cartilage.
3. Vocal process: directed forwards & gives attachment to the vocal lig. (cord).
• Each one articulates with the upper border
of the lamina of cricoid cartilage.
4. Muscular process: directed posterolat.
& gives insertion to the muscles which
move the arytenoid cartilage.

10. 5. Corniculate cartilages
• Each one is small cartilage nodule
lying on the apex of the arytenoid
cartilage.
6. Cuniform Cartilages
• Each one is a small cartilage nodule
lying infront of the corniculate
cartilage in the aryepiglottic fold.

11. Membranes of the larynx
1. Thyroidhyoid membrane
2. The quadrangular membrane
3. Cricothyroid membrane

12. Membranes of the larynx
1. Thyroihyoid membrane
• Attached above to the deep surface
of hyoid bone near its lower border.
• Attached below to the upper
margin of the thyroid cartilage.
• Pierced by internal laryngeal n. &
sup. Laryngeal a.

13. Membranes of the larynx
2. The quadrangular membrane
• It is the upper part of the fibro-
elastic membrane which lines
the larynx.
• Extends between the arytenoid
cartilage & the epiglottis.
• Its lower border is thickened to
form the vestibular lig. (false
cord)

14. Membranes of the larynx
3. Cricothyroid membrane
• It’s the lower part of the fibroelastic memb.
Lining the larynx.
• The ant. median part called the median
cricothyroid lig.
• the lat. Part of it (on each side) is triangular &
called the cricovocal membrane.
• Its upper border is called the vocal lig. (true
vocal cord) & its attached ant. To the inner
aspect of thyroid prominence & post. To the
vocal process of arytenoid cartilage.

15. Cavity of the larynx
Its divided into 3 compartments by
2 pairs of folds :
1. Upper folds Called “ Vestibular
folds” False vocal cords.
2. Lower folds called “ vocal folds “
true vocal cords.

16. Cavity of the larynx
• Compartments of the larynx:
1. Vestibule (upper compartment)
2. Ventricle or sinus of the larynx
(middle compartment)
3. Infraglottic (lower compartment)

17. Cavity of the larynx
• Rima vestibuli : is the space
between the 2 vestibular
folds.
• Rima glottidis : is the space
between the 2 vocal folds.

18. Muscles of the larynx
1. Extrinsic Muscles (the longitudinal muscles of the pharynx &
infrahyoid muscles)
2. Intrinsic Muscles (true laryngeal muscles) both attachments on the
laryngeal cartilages.

19. Muscles of the larynx
• Acording to their action they are divided into 5 groups:
1. Muscles which stretch the vocal cords.
2. Muscles which relax the vocal cords.
3. Muscles which abduct the vocal cords.
4. Muscles which adduct the vocal cords.
5. Muscles which adjust the size of the laryngeal entrance.

20. Muscles of the larynx!
1. Muscles which stretch the
vocal cords.
• The 2 cricothyroid muscles:
Act by lowering the thyroid cartilage
forwards so the distance between the
vocal process of arytenoid & the
laryngeal prominence is increased & the
vocal cords become stretched.

21. Muscles of the larynx
2. Muscles which relax the vocal
cords.
• The 2 thyroarytenoid muscles:
they relax the cords by pulling the arytenoid
cartilages forwards towards the laryngeal
prominence.

22. Muscles of the larynx
3. Muscles which abduct the
vocal cords.
• The 2 post. Cricoarytenoids:
They draw the muscular processes of the
artenoid cartilages backwards so that the
vocal prcesses become directed laterally.

23. Muscles of the larynx
4. Muscles which adduct the vocal
cords.
• Transverse arytenoid muscle:
It approximates the 2 arytenoid cartilages to each
other
• 2 lat. Cricoarytenoid muscles:
they draw the muscular process “forwards”, this
makes the vocal processes move medially

24. Muscles of the larynx
5. Muscles which adjust the size of
the laryngeal entrance
• 2 oblique arytenoids muscles:
they encircle the laryngeal orifice acting like a
sphincter.
• Aryepiglottic Muscles:
( not powerful to overcome the elasticity of the
epiglottis so they cant close the laryngeal
entrance)

25. Arterial supply of the larynx
•Arterial supply:
1. Sup. Laryngeal a. (branch of sup.
Thyroid a.)- upper half
2. Inf. Laryngeal a. (branch of inf.
Thyroid a.)- lower half

26. Venous drainage of the larynx
•Venous drainage:
1. Veins of the upper part join the sup.
Thyroid v. which ends in the I.J.V
2. Veins of the lower part join the inf.
Thyroid v. whuch ends in the
innominate v.

27. Lymphatic drainage of the larynx
1. Lymphatics of the vocal cords &
upper part drain into the upper
deep cervical L.Ns.
2. Lymphatics of the lower part drain
into the lower deep cervical L.Ns &
prelaryngeal L.Ns.

28. Nerve supply of the larynx
1. Motor supply of the laryngeal
muscles:
• All laryngeal muscles are supplied by
the recurrent laryngeal nerves except
cricothyroid m.
• Cricothyroid m. is supplied by the
external laryngeal n.

29. Nerve supply of the larynx
•Sensory supply of the mucous
membrane
1. Above the vocal cords is supplied by
the int. laryngeal n.
2. Below the vocal cords is supplied by
recurrent laryngeal n.

30. RECURRENT LARYNGEAL NERVE
• Rt. Recurrent laryngeal nerve
arises from the Vagus nerve at the
level of Subclavian artery, hooks
round it & then ascends between
the trachea & oesophagus.
• The Lt. Recurrent laryngeal nerve
arises from the Vagus in the
Mediastinum at the level of Arch of
aorta, loops round it & then
ascends into the neck in the
tracheo-oesophageal groove.
• Thus, Lt. Recurrent Laryngeal
Nerve has a much longer course
which makes it more prone to
paralysis as compared to the right
one.

31. SUPERIOR LARYNGEAL NERVE
• It arises from Inferior
Ganglion of the Vagus
nerve, descends behind
Internal Carotid artery & at
the level of Greater cornu of
Hyoid bone, divides into
External & Internal
branches.
• The external branch supplies
cricothyroid muscle while
the internal branch pierces
the thyrohyoid membrane &
supplies sensory innervation
to the larynx &
hypopharynx.

32. Vocal cord paralysis

33. CLASSIFICATION OF LARYNGEAL PARALYSIS
• Laryngeal paralysis can be :
Unilateral or Bilateral & may involve –
1. Recurrent laryngeal nerve
2. Superior laryngeal nerve
3. Both (Combined / Complete)

34. CAUSES OF LARYNGEAL PARALYSIS
In topographical manner they are :
1. Supranuclear : Rare
2. Nuclear : Vascular disease, Neoplastic disease, Motor neuron disease,
Polio & Syringobulbia
3. High vagal lesions : Post. fossa tumors, Tubercular meningitis, Fracture of
skull base, Nasopharyngeal cancer, Glomus tumor, Penetrating injury of
neck, Parapharyngeal tumors, Metastatic neck nodes, Lymphoma
4. Low vagal or recurrent laryngeal nerve
5. Systemic causes : Diabetes, Syphilis, Diptheria, Typhoid, Viral infections,
Lead poisoning
6. Idiopathic

35. VOCAL CORD POSITIONS

36. RECURRENT LARYNGEAL NERVE PARALYSIS
• Unilateral injury to recurrent
laryngeal nerve results in
ipsilateral paralysis of all the
intrinsic muscles of larynx
ecxept the cricothyroid.
(A) UNILATERAL • Clinical features :
• The vocal cords thus assumes a
median or paramedian
position & doesn’t move
laterally on deep inspiration.
- Asymptomatic
- Change in voice
 The voice in unilateral
paralysis gradually
improves due to
compensation by healthy
cord which crosses
midline to meet paralysed
one.
• Treatment : Generally no
treatment is required.

38. unilateral vocal cord palsy

39. (B) BILATERAL (B/L Abductor paralysis) :
• Position of vocal cords : All the intrinsic muscles of
larynx are paralysed, vocal cords lie in median or
paramedian position due to unopposed action of
cricothyroid muscles.
• Clinical features :
- Dyspnoea
- Stridor

40. Movement of Vocal cord during
inspiration & expiration

41. PARALYSIS OF SUPERIOR LARYNGEAL NERVE
(A) UNILATERAL
• Paralysis of cricothyroid muscle & ipsilateral
anaesthesia of the larynx above the vocal
cord.
• Causes :
- Thyroid surgery
- Thyroid Tumors
- Diptheria.
• Clinical features :
- Weak voice with decreased pitch
- Anaesthesia of the larynx on one side
- Occassional aspiration.
 Laryngeal findings include :
- Askew position of glottis - Ant. Comissure is
rotated to healthy side.
- Shortening of V.C. with loss of tension & V.C.
appears wavy
- Flapping of the paralysed vocal cord – V.C. sags
down during inspiration & bulges up during
expiration.
(B) BILATERAL
• An uncommon condition. Both the cricothyriod
muscles are paralysed along with anaesthesia
of upper larynx.
• Causes:
- Surgical or accidental trauma
- Diptheria
- Cervical lymphadenopathy
- Neoplastic disease
• Clinical features:
- Both V.C. paralysis
- Anaesthesia of larynx
- Cough
- Chocking fits
- Weak & husky voice

42. COMBINED/COMPLETE VOCAL CORD PARALYSIS
(Recurrent & Superior Laryngeal Nerve Paralysis)
(A) UNILATERAL :
• Paralysis of all the muscles of the larynx on one side except
interarytenoid which also receives innervation from opposite side.
Aetiology :
• Thyroid surgery
• Lesions of nucleus ambigus .
Clinical features :
• All the muscles of larynx on one side are paralysed
• V.C. lie in cadeveric position ie. 3.5mm from the midline
• Glottic incompetence results in hoarseness of voice & aspiration of
liquids

43. (B) Bilateral:
• Both recurrent & superior laryngeal nerves on both sides are
paralysed.
• Rare condition.
• Both cords lie in cadaveric position.
• Total anaesthesia of the larynx.
Clinical features :
-Aphonia: As V.C. cords doesn’t meet at all.
-Aspiration: due to incompetent glottis & laryngeal anaesthesia.
-Inability to cough: due to inability of V.C. to meet which results in retention of
secretions in the chest.
-Bronchopneumonia- due to repeated aspirations & retention of secretions.

44. Difference b/w adult and pediatric VC palsy
primarily related to the underlying causes, symptoms, and
management approaches.:
1.Underlying Causes:
1. Adult Vocal Cord Palsy: In adults, the most common causes of vocal cord
palsy are usually related to issues such as surgery, trauma, tumors (benign or
malignant), and neurological conditions like stroke. Idiopathic (unknown cause)
cases can also occur in adults.
2. Pediatric Vocal Cord Palsy: Common causes in pediatric cases include birth
trauma (injury during childbirth), congenital abnormalities, infections, and
neurological conditions like congenital nerve anomalies. Gastroesophageal
reflux disease (GERD) can also be a contributing factor in some cases.

45. Symptoms:
•Adult Vocal Cord Palsy: In adults, symptoms may include
changes in voice quality (hoarseness), difficulty breathing,
especially during exertion, and aspiration (food or liquids
entering the airway). Symptoms can vary based on the severity
and underlying cause.
•Pediatric Vocal Cord Palsy: Children with vocal cord palsy
may exhibit different symptoms, such as stridor (noisy
breathing), weak cry, and feeding difficulties. These symptoms
may vary based on the child's age and the cause of the palsy.

46. Pediatric airway and larynx

49. Clinical significance
The higher larynx in infants causes tounge to shift more superiorly , closer to
palate the tongue easily apposes the palate - airway obstruction
Larger size of tongue makes direct laryngoscopy more difficult
Solutions :
chin lift
jaw thrust
change in head position
use of oral airway
manually pulling the tongue
Epiglottis is more posteriorly positioned- blocking the view of vocal cords
during intubation .

50. Narrowest part of infant larynx occurs at the level of cricoid uncuffed tracheal
tubes have been traditionally preferred for children younger than 6 .
Vocal cords are angled  blind intubation may easily lodge in to the anterior
commissure rather than slide into trachea .
The larynx is located higher in the neck , thus making straight blades more useful
than curved blades .
Infants requires shoulder or neck roll to prevent hyperflexion caused by relatively
large occiput .( in adults , sniffing position – flexion a C6- C7 and extenxion at C1-C2 )

51. THANK YOU