anatomy and physiology of larynx

1. ANATOMY AND PHYSIOLOGY
OF LARYNX
DR KOMAL
ENT RESIDENT

2.  OBJECTIVES
 •To discuss the basic anatomy of the larynx
 •To enumerate the main functions of the
 larynx

3.  LARYNX:
 Commonly called- voice box
 Shape- tube shaped.
 Composed- muscles, cartilages, connective
 tissue.
 Location- in front of hypopharynx 3-6 cervical vertebra.
 Moves vertically in AP direction and can be passively moved
from side to side producing grating sensation called
 Larnyngeal crepitus.

6.  SHAPE AND SIZE:
 the shape of the larynx in lower side is circular and
from the upper it is triangular in shape.
 Its length is 4.3 cm
 transverse diameter is 4.2 cm and anterior
posterior diameter 3.6 cm.

7.  LARYNX:
 3 paired and 3 unpaired.
 PAIRED:
 Arytenoid cartilage
 Corniculate cartilage
 Cuneiform cartilage
 UNPAIRED:
 Thyroid cartilage
 Cricoid cartilage
 Epiglottis

8.  THYROID CARTILAGE:
 Largest cartilage consist of two alae meets anteriorly forming
an angle of 90 in males and 120 in females.
 Vc are attached to the middle of thyroid angle.
 Most of the laryngeal fb are arrested above the vc.
 larger in males than females
 Hyaline cartilage

9.  LINNING OF THE LARYNX:
 superior of the vocal fold is non karatinized
stratified squamous epithelium,
 inferior to the vocal fold is pseudo stratified
columnar epithelium.

10.  posterior angles are prolonged into processes
termed as the superior and inferior cornu.
 The superior cornu is long, and narrow, directed
upward, backward,and Medially which gives
attachment to the lateral hypothyroid ligament.
 •The inferior cornu is short and thick, it is directed
downward.

11.  CRICOID CARTILAGE:
 A ring of hyaline cartilage known as SIGNET RING.
 Hyaline cartilage.
 It is the only cartilage that forms a complete ring..
 Its post part is expanded to form a Lamina while anteriorly it
forms an arch. it forms the lower and posterior parts of the
wall of the larynx.
 attached to the first ring of cartilage of the trachea by the
cricotracheal ligament
 the thyroid cartilage is connected to the cricoid cartilage by the
cricothyroid ligament.

13. EPIGLOTTIS:
 •It is a large leaf-shaped piece of elastic cartilage, it forms
anterior wall of laryngeal inlet.
 It is attached to the body of hyoid bone by hypoepiglottic
ligament, which divides it into the suprahyoid and infrahyoid
epiglottis.
 A stalk like process of epiglottis (petiole) attaches the
epiglottis to the thyroid angle.
 Ant surface of the epiglottis is seperated from thyrohyoid
membrane and upper part of the thyroid cartilage y a potential
space called as the pre-epiglottic space which may be
invaded in ca of supraglottic larynx or the base of the tongue.

15.  ARYTENOID CARTILAGE:
 these are paired Triangular pieces, hyaline cartilage located
at the posterior, superior border of the cricoid cartilage at the
back of the larynx.
 It is pyramidal in form and has three surface, a base and a
apex.
 Base articulates with the cricoid cartilage.
 Muscular process gives attachment to the intrinsic muscles
and the vocal process gives attachment to the vocal cord and
apex supports corniculate cartilage.

16.  CORNICULATE CARTILAGES:
 Two small conical nodules
 horn shaped , fibroelastic cartilage.
 Each articulates with the apex of arytenoid cartilage.

17. CUNEIFORM CARTILAGES:
 These are rod shaped each is situated in the aryepiglottic fold
in front of the corniculate cartilage and provides passive
support to the fold.

18. LARYNGEAL LIGAMENTS:
• EXTRINSIC
 – Thyrohyoid
 membrane and
 ligaments
 – Cricothyroid
 membrane and
 ligaments
 – Cricotracheal
 ligament
 – Epiglottis

19. LARYNGEAL JOINTS:
 Cricoarytenoid: it is a synovial joint formed between the
base of arytenoid and a facet.
 2 movements occurs
 Rotatory: AC moves in vertical axis thus abducting and
adducting the vocal cords.
 Gliding: arytenoid glides towards the other or away from it
thus closing or opening the posterior part of glottis.
 Cricothyroid joint: synovial joint, formed by the inferior
cornu of thyroid cartilage with a facet on cricoid cartilage.

20. LARYNGEAL LIGAMENTS:
 INTRINSIC:
 Cricovocal membrane: it is a triangular fibroelastic
membrane.
 Its upper border forms the vocal ligament
 Its lower border forms the conus elasticus where subglottic
foreign bodies get impacted.
 Quadrangular membrane: lies deep to the mucosa of
aryepiglottic folds.
 Stretches between the epiglottic and arytenoid cartilages.
 Lower border forms the vestibular ligament which lies in the
false vocal cord.

22. EXTRINSIC LIGAMENTS:
 Thyrohyoid membrane: connects thyroid cartilage to
hyoid bone. Pierced by superior laryngeal vessels and
laryngeal nerve.
 Cricothyroid membrane: connects thyroid cartilage to
the cricoid cartilage
 Cricotracheal membrane: connects cricoid cartilage to
the first tracheal ring.

23.  INTRINSIC LIGAMENTS:
 THE CORNUS ELASTICUS-- is
 composed mainly of yellow elastic tissue. It
connects the thyroid, cricoid, arytenoid cartilage to
one another .
 THYROEPIGLOTTIC LIGAMENT----
 is a long, slender, elastic cord which connects the
stem of the epiglottis with the angle of thyroid
cartilage.

24.  MUSCLES OF LARYNX:
 Extrinsic muscles (attaches larynx to the surrounding
structures)
 •divided into the elevators and depressors of larynx:
 Elevators: primary elevators act directly as they are attached
to the thyroid cartilage includes stylopharyngeus,
salpingopharyngeus, palatopharyngeus and thyrohyoid.

25.  Secondary elevators: they act indirectly as they are
attached to the hyoid bone and includes mylohyoid, digastric,
stylohyoid and geniohyoid.
 Depressors: they include sternohyoid, sternothyroid and
omohyoid.

26.  EXTRINSIC MUSCLES:
 The Geniohyoid Muscle
 They lie superior to the mylohyoid muscle to body
of the hyoid bone
 The Stylohyoid Muscle
 Insertion: the body of the hyoid bone

27.  The thyrohyoid
 muscle - It arises from the oblique line on the
lamina of the thyroid cartilage, and to the
 greater cornu of the hyoid bone.

28.  INTRINSIC MUSCLES OF LARYNX:
 Acts on the vc and laryngeal inlet.
 Those acting on the vc:
 Abductors: posterior cricoarytenoid
 Adductors: lateral cricoarytenoid, interarytenoid and
thyroarytenoid
 Tensors: cricothyroid vocalis
 Those acting on the laryngeal inlet:
 Openers of LI: thyroepiglottic
 Closers: interarytenoid and aryepiglottic.

30.  CAVITY OF THE LARYNX: it starts at the laryngeal inlet
where it communicates with the pharynx and ends at the lower
border of cricoid cartilage where it continues with the lumen of
the trachea.
 2 pairs of folds vestibular and vocal divides the cavity into the
3 parts:
 • Divided into 3 parts:
 – Vestibule
 – Ventricle (sinus of larynx)
 – Subglottic space (infraglottic larynx) extends from the vc to
the lower border of cricoid cartilage.

31.  False vocal cords (vestibular folds): 2 in no these
are fold of mucous membrane contains vestibular ligament,
fibers of thyroarytenoid muscle and mucus glands.
 True vocal cords: (vocal folds): pearly white sharp
bands extending from the middle of the thyroid angle to the
vocal process of arytenoid. Each vc consists of vocal
ligament.
 Glottis: (rima glottidis): elongated space between vocal
cords anteriorly and vocal processes post
 24mm in males 16mm in females.

33.  Reinke’s space:
 Under the epithelium of vocal cord is a potential space with
scanty subepithelial connective tissues bounded above and
below by arcuate lines, infront by ant comissure and behind
by vocal process of arytenoid. oedema of this space causes
fusiform swelling of the membranous cords.

34. BLOOD SUPPLY:
 • Upper Larynx (above vc)
 – Superior laryngeal
 Artery brancy of sup thyroid.(EC)
 • Lower Larynx (below vc)
 – Inferior laryngeal Artery(thyrocervical
 turnk)

35. VENOUS DRAINAGE:
 Upper larynx:
 Superior laryngeal vein
 Superior thyroid vein
 Internal juglar vein
 Lower larynx:
 Inferior laryngeal vein
 Inferior thyroid vein
 Subclavian vein

37. NERVE SUPPLY:
 Motor supply: recurrent laryngeal nerve
 Sensory nerve supply up to the vocal fold is internal
laryngeal nerve and below the vocal is recurrent
laryngeal nerve.

38.  BASIC FUNCTIONS:
 • Protection
 • Respiration
 • Phonation
 • Fixation of chest
 • Closure of glottis