1. Larynx – what to know ! Dr. S. Parthasarathy
MD., DA., DNB, MD (Acu), Dip. Diabetes, DCA, Dip. Software statistics-
PhD ( physiology), IDRA, FICA

2. What is it ?
It consists of a complex arrangement of muscles, cartilage, membranes and ligaments. It extends from C3 to C6 in the midline
Hanging from the hyoid to trachea
Some what higher in children( 2nd to fifth? cervical vertebrae) and females
Organ designed to coordinate deglutition respiration and phonation

3. What does it do ?? Breathing Preventing aspiration during deglutition
Voice

4. Elevated epiglottis abutting the nasopharynx – more useful for aspiration prevention than phonation !!

5. Three levels of aspiration prevention

6. False vocal cords – inferior orientation - 30 mmHg--Develop a pressure to cough
True vocal cords superior orientation – stops ingress of fluids – 140 mmHg –
How difficult to ventilate in spasm !!

7. Male and female ??

8. Anatomy
Anterior – superficial structure, is covered by the fascia platysma and skin
Posterior –prevertebral , cervical vertebrae
Superior – pharynx
Inferior – becomes continuous with the trachea

9. Structure Cartilages (nine) – three unpaired and six paired Ligaments
Muscles

10. Total nine
Epiglottis
Thyroid
Cricoid
Corniculate
Cuneiform
Arytenoid

11. Epiglottis !!

12. Epiglottis (elastic) – ‘leaf’-shaped; the lower, narrower end is attached to the thyroid cartilage by the thyro-epiglottic ligament
upper broader end is free to project superiorly
median glossoepiglottic fold and pharynx as two lateral glossoepiglottic fold

13. In Deglutition
Hyoid bone move upward and forward
Epiglottis bent posteriorly on laryngeal inlet
Food slips to the lateral surface
Taste sensation
Assist in phonation
Gag reflex
Prevent aspiration of food

14. Superior and inferior cornua
Thyroid
Two laminae
FUSION MORE IN MALE
Notch
Superior and inferior cornua

15. Thyroid cartilage
In females, the sides join at approximately 120 degrees
In males at closer to 90 degrees.
This smaller thyroid angle explains the greater laryngeal prominence in males (the “Adam's apple”), the longer vocal cords, and the lower pitched voice

16. Vocal cords at the lower border

17. Cricoid cartilage (hyaline) – ‘signet ring’-shaped and situated at the C6 level. It articulates on its lateral border with the thyroid cornua, and on its upper border with the arytenoid cartilages..

18. Cricoid cartilage
. cricoid is derived from the Greek words krikos and eidos, meaning shaped like a ring
Only laryngeal cartilage- complete ring
Smaller but thicker & stronger than thyroid

20. The two light arytenoid cartilages are shaped like three-sided pyramids, and they lie in the posterior aspect of the larynx-posterior joint
Crico arytenoid arthritis
In rheumatoid and SLE
The lateral extension of the arytenoid base is called the muscular process.
Important intrinsic laryngeal muscles, lateral and posterior cricoarytenoids, originate here.
The medial extension of the arytenoid base is called the vocal process.

21. Two sets of paired fibroelastic cartilages are embedded in each aryepiglottic fold.[
The cuneiform and corniculate cartilages reinforce and support the aryepiglottic folds and may help the arytenoids move

24. Safe muscle of the larynx
Only this opens
Safe muscle of the larynx

25. Mechanism to prevent aspiration
It contracts in 14 seconds while posterior crico arytenoid in 44 seconds
Mechanism to prevent aspiration

26. Elevation of larynx- thyrohyoid, mylohyoid
Depression of larynx- sternothyroid, sternohyoid
Abductors – Posterior cricoarytenoid
Adductor - Lateral cricoarytenoid, interarytenoid
Regulation of cord tension
– Cricothyroid (Tensor)
– Thyroarytenoid – (Relaxors)
– Vocalis (fine adjustment)

27. Vascular supply Superior laryngeal artery - superior thyroid A
Inferior laryngeal artery – inferior Thyroid A
Crico thyrioid artery -superior thyroid A
SLV – STV -- IJV ILV - Brachiocephaliv V

28. Nerve supply Epiglottis – glossopharyngeal nerve
Above vocal cords – internal branch of superior laryngeal nerve
Below vocal cords – recurrent laryngeal nerve
Motor
All muscles of the larynx are supplied by the recurrent laryngeal nerve except cricothyroid
( ext. branch – superior laryngeal nerve )

29. Right recurrent –
Subclavian round
Left – aortic arch
rounding
Lengthier

30. Voice Vibrations/ second of the vocal cord Pitch = L/TM Depends on:
a. Length of VC.
b. Mass of VC.
c. Tension of VC.
Men Hz
Women – 150 – 1000

31. Vocal folds vibrate faster as they're pulled longer, thinner, and more taut and
vibrate more slowly when they're shorter, thicker, and floppier.
The cricothyroid muscle and thyroarytenoid muscle coordinate with each other to create different pitches.

35. Thyro arytenoid causes relaxation
When it is gone, tension – pitch goes up
Cricothyroid – EXT – laryngeal nerve – tenses
Problem to the nerve – relaxation – low pitch

36. Laryngeal paralysis can be
Unilateral or Bilateral & may involve –
1. Recurrent laryngeal nerve
2. Superior laryngeal nerve
3. Both (Combined / Complete)

37. The recurrent laryngeal nerve may be traumatized during surgery on the thyroid and parathyroid glands.
Malignancy or benign processes of the neck, trauma, pressure from an ET or a laryngeal mask airway, and stretching the neck may also affect the nerve

38. 1.5
3.5
7.5

42. Downloaded from net for closed academic purpose only

43. Bilateral recurrent N palsy
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

44. This is normal !

45. Inspiration and expiration in BL RLN palsy

46. PARALYSIS OF SUPERIOR LARYNGEAL NERVE
Unilateral
Weak voice with decreased pitch
- Anaesthesia of larynx on one side
- Occassional aspiration.
- 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
Bilateral
Both V.C. paralysis
- Anaesthesia of larynx
- Cough
- Chocking fits
- Weak & husky voice

47. Bilateral incomplete RLN
On inspiration
Bilateral incomplete RLN
Addutors are intact !!

49. Summary Larynx – borders Cartilage Three levels of aspiration
Sensory supply
Muscles and their action
Safe muscle
Various positions

50. What is the laryngeal activity which comes with class ?
Yawning

51. Thank you