Clinical anatomy and physiology of larynx

For undergraduate students (MBBS)

1. Dr.Ramesh Parajuli,MS
Chitwan Medical College Teaching Hospital, Chitwan,
Nepal

2. •Laryngeal cartilages and membranes
•Laryngeal muscles: function
•3 subdivisions of larynx
•Nerve supply of larynx
•Functions of larynx
Learning objectives

4. Anatomy of larynx
•Rigid skeletoncartilages,
muscles, ligaments & membranes
•Extends from hyoid bone above to
cricoid cartilage below
•Opposite to C3 to C6 cervical
vertebra
•Laryngeal crepitus:
absent in post-cricoid carcinoma

5. Laryngeal cartilages
•3 unpaired and 3 paired cartilages
•Unpaired:
1.Thyroid
2.Cricoid
3.Epiglottis
•Paired:
1.Arytenoid
2.Cuneiform ( Wrisberg)
3.Corniculate (Santorini)

6. Histological types of laryngeal cartilages
(1) Elastic:
Epiglottis, corniculate, cuneiform & apex of arytenoid
Little or no calcification
(2) Hyaline:
Thyroid, cricoid & remaining arytenoid
Calcify as age advances
Ossification begins by 25 yr & is completed by 60 yr

7. 1.Thyrohyoid membrane:
2.Cricothyroid membrane:
cricothyrotomy
•Cricoid cartilage: only rigid &
complete ring among the
cartilages forming larynx and
trachea

8. Cartilages (anterior)

9. Cartilages (posterior)

10. Laryngeal membranes
(I).Extrinsic membranes:
1.Thyrohyoid membrane
2.Cricothyroid membrane
3.Cricotracheal membrane
(II).Intrinsic membranes:
1.Cricovocal membrane forms vocal ligament
2.Quadrangular membraneforms the vestibular ligament

11. Larynx (sagittal section)

12. Larynx (coronal section)

13. NPL(Nasopharyngolaryngoscopy)

14. Vocal fold

15. Pediatric Larynx Vs Adult larynx
1.Subglottis is the narrowest part
2.Loose submucosal tissues (swell up
easily)
3.Positioned high (C3-C4)
4.Soft cartilages collapse easily

16. Subdivisions of larynx
A.Supraglottis: laryngeal
inlet to apex of ventricle
B. Glottis: apex of ventricle to
1cm below
C. Subglottis: lower glottic
border to lower cricoid
border

17. Subsites
A.Supraglottis:
1.Epiglottis 2. AE fold 3. FVC 4. Ventricle
B. Glottis:
1.TVC 2. Anterior commissure 3. Posterior commissure
C. Subglottis

18. Intrinsic Muscles
A. Acting on vocal cords
Abduction ® Posterior crico-arytenoid
Adduction ® Lateral crico-arytenoid
Transverse arytenoid (inter-arytenoid)
Thyro-arytenoid
Tension + lengthening ® Cricothyroid
Relaxation + shortening ® Vocalis ( internal part of thyroarytenoid)

19. B. Acting on laryngeal inlet
Opener ® Thyro-epiglottic (part of thyroarytenoid)
Closer ® Inter-arytenoid (oblique part)
Ary-epiglottic(Posterior oblique part of interarytenoid)

20. Extrinsic laryngeal muscles
•Elevators of larynx
Primary elevators secondary elevators
· Stylo-pharyngeus · Mylohyoid
· Salpingo-pharyngeus· Stylohyoid
· Palato-pharyngeus · Geniohyoid
· Digastric
•Depressors of larynx (strap muscles of the neck)
Sternohyoid ,Sternothyroid , thyrohyoid ,Omohyoid

21. Posterior cricoarytenoid

22. Lateral cricoarytenoid

23. Transverse Inter-arytenoid

24. Cricothyroid

25. Oblique Inter-arytenoid

26. Mucous Membrane
1.Stratified squamous epithelium

2.Pseudostratified ciliated columnar (respiratory) epithelium

27. Nerve Supply
Superior Laryngeal Nerve (SLN):
•Internal: Sensory supply to supraglottis & glottis
•External: Motor supply to cricothyroid muscle
Recurrent Laryngeal Nerve(RLN):
•Sensory supply to subglottis
•Motor supply to all intrinsic muscles except cricothyroid

28. Blood Supply
Arterial supply:
•Laryngeal branch of superior & inferior thyroid artery
Venous drainage:
•Superior thyroid vein ® internal jugular vein
•Inferior thyroid vein ® innominate vein

29. Lymphatic Drainage
Supraglottis: Upper deep cervical nodes
Subglottis: Pretracheal + lower deep cervical nodes
Glottis: has no lymphatics

30. Functions of Larynx
1.Protection of lower airway: primary function
(i) Closure of larynx: three tier mechanism
(ii) Cough reflex
2.Phonation (voice production): secondary function
3.Respiration
4.Chest fixation by glottic closure: coughing,micturition,defecation

31. Thank you