medical for post graduate

1. Anatomy of Larynx and
Tracheobronchial tree
Dr Raju Kafle
1st year resident
NMC-TH
ORL-HNS dept.
1

2. Development
• At 4wk embryo: Respiratory diverticulum /
laryngotracheal diverticulum appears as outgrowth
from ventral parts of foregut.
• Initially is in open communication with foregut
• When diverticulum expands caudally, the
tracheoesophageal ridges seperates it from foregut.
• Later, ridges fuses to form tracheoesophageal septum
• Dorsal portion : esophagus
• Ventral portion: trachea and lung buds
• This process of fusion commences caudally to cranial
end where edges remains separate- bounding slit like
aperture through which tubes opens into pharynx.
2

3. • So epithelium of internal lining of larynx,
trachea and bronchi,as well as that of lungs :
endodermal origin
• Cartilagenous, muscular and connective tissue
components of trachea and lungs : dv from
splanchnic mesoderm surrounding foregut.
• Cartilages and muscles of larynx originates from
mesenchyme of 4th and 6th pharyngeal arches.
Primitive larynx: at cranial part of
laryngotracheal groove
Bounded vertically by caudal part of
hypobranchial eminence( copula) and laterally by
ventral folds of 6th arches.
3

4. • Arytenoid swellings appears on both side of groove,
as they enlarges and approximated to each other and
to caudal part of hypobranchial eminence(from which
epiglottis develops)
• Initially opening : vertical slit /cleft like
• Later T- shaped with appearance of arytenoids.
• The arytenoid swellings grows upwards and deepens
to form primitive aryepiglottic folds
• Thus in turn produces a further aperture above level
of primitive aperture which itself becomes glottis.
• 2nd month of IUL: Arytenoid swellings differentiates
into arytenoid and corniculate cartilage,
• folds joining them to epiglottis becomes aryepiglottic
folds in which cuneiform cartilages are developed as
derivatives of epiglottis.
4

5. • At about time cartilages are formed , laryngeal
epithelium also proliferates, resulting in temporary
occlusion of lumen (upto 3rd months).
• Subsequently vacuolization and recanalization
produces a lateral recess( laryngeal ventricles) and
lumen is restored.
• These recess bounded by folds of tissues that
differentiate into false and true vocal cords.
• Because musculature of larynx is dv from mesenchyme
of 4th and 6 th arch , all laryngeal muscles are supplied
by branch of vagus verve
• 4th arches structure: superior laryngeal nerve
• 6th arch structure: recurrent laryngeal nerve
5
4th arch 6th arch
Thyroid cartilage,
Corniculate and
Cuneiform cartilage
Arytenoid cartilage
Pharyngeal and
extrinsic muscles,
Cricothyroid
All intrinsic muscle(
except cricothyroid)

6. • During its separation from foregut, lung buds
forms the trachea and bronchial buds.
• At beginning of 5th week, each buds enlarges to
form right and left main bronchi
• Rt side : three secondary bronchi---- for 3
lobes
• Lt side : two secondary bronchi ---- for 2
lobes
• Invades pericardioperitoneal canals on each side of
foregut and gradullay fills it.
• Ultimately, pleuroperitoneal and pleuropericardial
folds seperates the pericardioperitoneal canal from
peritoneal and pericardial cavity
• Remaining spaces forms primitive pleural cavities.
6

7. • During further development: secondary bronchi
divides
• 10 tertiary ( segmental ) bronchi each side,
creating bronchopulmonary segment of adult
lungs
• End of 6th month: approx. 17 generations of
subdivisions have formed.
• Additional six divisions during post natal life.
• Maturation of lungs:
• Pseudoglandular period (5-16wk) branches to form
terminal bronchioles
• Canalicular period (16-26 Wk): terminal bronchioles to
form respiratory bronchioles
• Terminal sacs period (26wk to birth): terminal sacs and
capillaries close contact
• Alveolar period (8mo- childhood): maturation of alveoli,
well developed epithelial contacts.
7

8. Congenital disorders
Larynx
Supraglottic abnormalities
• Laryngomalacia:
• Lymphangioma
• Bifid epiglottis
Glottic
• laryngeal webs
• Atresia
• Vocal cord paralysis
Subglottic
• Congenital subglottic stenosis
• Subglottic hemangioma
• Laryngeal and
laryngetracheoesophageal cleft 8
Trachea and bronchus
• Agenesis
• Stenosis
• Tracheomalacia or,
bronchomalacia
• Vascular ring
• Vascular sling
• Congenital cysts and
tumors

9. • 1st m/c cause of congenital cause of stridor : high pitch
fluttering inspiratory, at birth or shorlty after, severity
increased at 9 month , gradually diminished by age of 2yrs,
very rarely may persists
• Intermitttent: feeding, active, crying ,worst in supine (when
asleep, sleep on back-disappear)
Anatomical abnormalities:
• Epiglottis: tall and omega shaped
• Aryeepiglottic folds are short and tightly tethered to epiglottis
• Redendent mucosa and submucosa of AE fold medially
that may prolapse into the airway
• Prominent , elongated arytenoid cartilage 9
A. During inspiration (collapse) B. during expiration with flexible laryngoscope
Supraglottis
laryngomalacia

10. Laryngoceles
Air filled dilatation of ventricle / sinus of Morgagni
• hoarseness, stridor and dysphagia
• Can be Acquired: repeated sustained high transglottal pressures
( trumpet players, weight lifting)
• Growth of a laryngocele - constrained by the surrounding
tissues - so expands upwards into the paraglottic space
anterior to the piriform fossa, and superiorly to expand the
aryepiglottic fold and reach the vallecula : internal
laryngocele
• It can extend to the thyrohyoid membrane, may pierce to
form an External laryngocele (palpable in the neck).
10

11. • Abnormal dilatation or herniation of saccule
• Expanding mucus-filled cyst d/t glandular secretions
accumulation because it has no opening in larynx , No air within (
vs ventricle-laryngoceles)
Types:
• Anterior type : if medially and posterior from saccule –
protrudes b/w true and false vocal cords)
• Lateral type : m/c , expands posteriorly b/w false cord
and AE fold)
• Can expand in a similar direction to a laryngocele (type 1 and
type 2), hoarseness and stridor + acute respiratory obstruction
may occur (if infected)
Anatomical abnormalities
• Development failure to maintain the patency of orifice b/w
saccule and ventricle.
11
Saccular cyst

12. Vascular malformations
Lymphatic malformation( cystic hygroma- d/t abnormal devt of
lymphatics), venous malformations and Arteriovenous-
malformation
Bifid epiglottis
Rare , epiglottis fails to fuse in midline , thus cleft upto tubercle
Feeding difficulty ( d/t aspiration) and stridor( d/t collapse and
enfolding of 2 halves of epiglottis)
12

13. Glottis
Laryngeal webs:
• failure of complete canalization of larynx.
• inspiratory, weak-high pitched, squeaky voice
• Common in glottis, supraglottic( rare)
Others:
• laryngeal atresia: Incompatible with life (unless asscociated TE-
fistula ,or emergency tracheostomy is performed in delivery
room)
• Vocal cord paralysis : 2nd m/c cause, unilateral or bilateral
• Cri-du-chat syndrome(chr 5p deletion), microcephaly, down-
slanting palpable fissures, MR, hypotonia—post part of glottis
remains open during phonation, diamond shaped appearence in
endoscopy.
13

14. Subglottis
Congenital subglottic stenosis
• 3rd m/c cause of congenital stridor
• Defective canalization of cricoid cartilage and or, conus elasticus
• Gross thickening of anterior- lamina of cricoid or ,small , elliptical
, thickened cricoid cartilage with excessive submucosal soft tissue
• Myer cotton grading: grade 1 to 4
Subglottic hemangioma:
• Inspiratory or biphasic stridor,
• Natural history: 6-12 months- proliferative phase, complete
involution over 1-5 years)
Laryngo and laryngotracheo-oesophageal cleft
• Failure of posterior cricoid lamina- post laryngeal cleft
• Failure of trachea-oesophageal septum leads to : laryngotraceo-
oesophageal cleft
14

15. Trachea and bronchi
• Agenesis
• Tracheomalacia and bronchomalacia
• Reduced stiffness of tracheal /bronchial wall: collapse
during expiration, if severe- respiratory obstruction)
• Tracheo-oesophageal fistula:
• As in figure
• Vascular ring : m/c double aortic arch from ascending
aorta-one to right another to left and reuniting posterior to
oesophagus—compression of trachea and esophagus)
• Vascular sling: m/c aberrant Innominate artery, tracheal
compression( less airway obstruction than vascular ring)
• Congenital cyst( E.g. bronchogenic cyst) and tumors.
15
Tracheo-oesophageal fistula
 Type A : m/c, 90% of all
 Type B : isolated esophageal
atresia (4%)
 Type C : H-type (4%)
 Type D/E: both-1/ 1%

16. • Hollow, musculoligamentous structure + cartilaginous
framework that caps the lower respiratory tract.
• Opposite to 3rd to 6th cervical vertebra (slight higher in
women and children)
• Length*width*AP = male: 44mm*43mm*36mm
Female 36*mm41mm*26mm
Cavity of the larynx:
• Continuous below with the trachea
• Above opens into pharynx immediately posterior
and slightly inferior to the tongue and the posterior
opening-oropharyngeal isthmus of the oral cavity.
Acts as both
• Spinchter( valve) to close lower respiratory tract
• Instrument to produce sounds
In addition: Creates high intrathoracic pressure for
coughing and lifting
16
Larynx: overview

17. • It is suspended from the hyoid bone above and attached to the trachea
below by membranes and ligaments.
• Highly mobile in the neck
• can be moved vertically and anteroposterior direction during swallowing and
phonation-- action of Extrinsic muscles that attach either to the larynx itself or
to the hyoid bone.
• Also passively side to side : laryngeal crepitus
• It is composed of:
• 3 large unpaired cartilages (cricoid, thyroid, and epiglottis);
• 3 small , paired cartilages (arytenoid, corniculate, and cuneiform);
• Fibroelastic membrane and numerous intrinsic muscles.
17

18. Laryngeal Framework
Hyoid bone: U-shaped bone
• Suspended from the tips of the styloid processes by stylohyoid
ligaments.
• Provides attachment to different infrahyoid and suprahyoid muscles
Parts: Body, Two greater horns/ cornua, Two lesser horns/ cornua.
Development:
• Lesser cornua (2nd branchial arch), the greater cornua( 3rd arch) and
the body from fused ventral ends of both.
• Chondrification begins at 5th fetal week, completed in 3rd and 4th
months.
• Ossification: 6 centres, i.e. a pair for the body and one for each cornu.
• Ossification : greater cornua shortly before or after birth, and lesser
cornua around puberty.
18

19. Laryngeal cartilages
 Cricoid cartilage :
• Most inferior of all laryngeal cartilages, completely encircles the
airway
• Signet ring shape
• With broad lamina -posteriorly and ,
• Much narrower arch of cricoid cartilage encircling anteriorly
• Two shallow oval depressions separated by a vertical ridge
• The esophagus is attached to the ridge ,
• Depressions are for attachment of the posterior crico-
arytenoid muscles.
Facets:
• Facet on superolateral surface of the lamina : articulates with
base of arytenoid cartilage;
• Facet on the lateral surface of the lamina : articulation of
medial surface of the inferior horn of the thyroid cartilage
19

20.  Thyroid cartilage
• Largest, longest of the laryngeal cartilages, consists of
right and left lamina- widely separated posteriorly, but
converge and join anteriorly
• Most superior point of fusion between the two laminae
projects forward as the laryngeal prominence ('Adam's
apple’).
• The angle b/w two lamina is more acute in men (90°)
than in women (120°) ,hence more apparent in men.
• Superior thyroid notch separates the two laminae as they
diverge laterally.
(Both the superior thyroid notch and the laryngeal prominence are
palpable landmarks in the neck)
• Less distinct inferior thyroid notch in the midline along
the base of the thyroid cartilage.
20

21. Posterior margin of each lamina elongates to form superior
horn and inferior horn.
•Medial surface of the inferior horn : facet for
articulation with the cricoid cartilage;
•Superior horn is connected by a ligament to the posterior
end of the greater horn of the hyoid bone.
• Lateral surface of each lamina is marked by a ridge
(oblique line) : that curves anteriorly from base of the
superior horn to a little short of midway along the inferior
margin of the lamina.
• Ends of oblique line expands to form superior and inferior
thyroid tubercles. The oblique line is a site of attachment
for the extrinsic muscles of the larynx (sternothyroid,
thyrohyoid, and inferior constrictor) 21

22.  Epiglottis
22
• Thin, leaf-shaped cartilage
Attachment:
Posterior aspect of thyroid cartilage Via thyro-epiglottic ligament in
midline approx. midway b/w the laryngeal prominence and inferior
thyroid notch.
• Also to hyoid bone anteriorly by hyoepiglottic ligament
• The upper margin of the epiglottis is behind the pharyngeal part of
the tongue.
• Surfaces
• Posterior or laryngeal surface
• Anterior or lingual surface
• The inferior half of posterior surface of epiglottis: raised slightly
to form epiglottic tubercle.
• Indentations posteriorly: gland pits into which mucus gland
projects

23.  Arytenoid cartilages
Pyramid-shape, three surfaces:
• Medial surface of each cartilage faces the other;
• Anterolateral surface has two depressions, separated by a
ridge, for muscle (vocalis) and ligament (vestibular ligament)
attachment.
• Posterior surface: covered by transverse arytenoid
• Base : Concave and articulates with cricoid cartilage;
• Apex : Articulates with a corniculate cartilage;
• Anterior angle of the base of arytenoid cartilage elongates into
a vocal process where vocal ligament is attached.
• The lateral angle : similarly elongates into muscular process
for attachment of the posterior and lateral Crico-arytenoid
muscles.
23

24. Corniculate and Cuneiform cartilage
Corniculate
• Two small conical cartilages , whose bases articulate
with the apices of the arytenoid cartilages.
• Their apices project posteromedially towards each other
Cuneiform
• Two small club-shaped cartilages lie anterior to the
corniculate cartilages .
• Are suspended in the part of the fibroelastic membrane
of the larynx( quadrilateral membrane) – which
attaches the arytenoid cartilages to the lateral margin of
the epiglottis.
24

25. Calcification of laryngeal cartilage
• Epiglottis, corniculate, cuneiform, apices of arytenoid =
elastic fibrocartilage
• Little tendency to calcify
• Thyroid , cricoid and all other part of arytenoid= hyaline
cartilages, begins calcifying in late teen or early 20’s
• Thyroid cartilage : starts in inferior cornu and then
anterior and superior , till entire rim is involved
• Calcification of cricoid cartilage and arytenoid( posterior
part): confused at radiology as FB
• Arytenoid: body and ,muscular process in 4th decade ,
vocal process donot calcify.
25

26. Extrinsic ligament
Thyrohyoid membrane
Tough fibroelastic ligament - spans b/w superior margin of thyroid
cartilage below and hyoid bone above.
Attachment:
• Upper border of thyroid cartilage + adjacent anterior margins of
superior horns, then inserts into greater cornu and posterior
surface of body of hyoid.
• Lateral part of each side: Aperture for superior laryngeal arteries,
nerves, and lymphatics
• Posterior borders thickens to form lateral thyrohyoid
ligaments.
• Also thickened anteriorly in the midline : median thyrohyoid
ligament.
• Occasionally, small cartilage - triticeal cartilage presents (in
each lateral side) 26

27. Hyo-epiglottic ligament
• Extends from the midline of the epiglottis, anterosuperiorly
to the body of the hyoid bone.
• Divides epiglottis: Suprahyoid and infrahyoid part
Cricotracheal ligament
• Runs from the lower border of the cricoid cartilage to the
adjacent upper border of the first tracheal cartilage.
27

28. Intrinsic ligaments
Fibroelastic membrane: 2 parts by laryngeal ventricle
Cricothyroid ligament/ cricovocal/ conus elaticus
• Arch of cricoid cartilage( lower border) to upper free margin b/w
middle thyroid angle to vocal process
• scaffolding the Vocal ligament
Quadrangular membrane : On each side runs b/w the lateral
margin of the epiglottis and anterolateral surface of arytenoid
cartilage of same side.
• It is also attached to corniculate cartilage.
• Upper margin forms frame of AE-fold.
• Scaffolding the Vestibular ligament
28

29. Laryngeal joints : synovial joint
 Cricothyroid joint
• In facet b/w the inferior horns of the thyroid cartilage and the
cricoid cartilage, surrounded by capsule
• Actions: To enable thyroid cartilage to move forward and
tilt downwards on the cricoid cartilage lengthen /
puts tension on the vocal ligaments
 Crico-arytenoid joint
• In facets of superolateral surfaces of cricoid and base of
arytenoid cartilages
• Actions: Enable arytenoid to slide away or towards each
other and rotatation (abduct and adduct the vocal ligaments)
Innervations-- branches of recurrent laryngeal nerves.
.
29

30. Mucus membrane of larynx
• Mostly by : pseudostratified ciliated columnar ( respiratory type)
• Upper half of posterior surface of epiglottis
• Upper part of AE fold
• Posterior glottis
• Vocal folds
Vocal fold: possess no glands, lubricated by mucus from glands within saccules
• Squamous epithelium of vocal fold , therefore prone to dessications if these glands
cease to function (for ex after radiation)
30
Non keratinizing stratified squamous

31. Cavities of larynx
Extension: laryngeal inlet to lower border of the cricoid
cartilage, where it continues into the trachea
• formed of fibroelastic membranes
• Lined with mucous membrane which folds over the
free edges of these membranes
On either side,
• the continuity of the fibroelastic membrane is interrupted
between the upper and lower folds.
• The folds project into the lumen of the cavity and
divide it into upper and lower parts,
(b/w these folds laryngeal ventricle)
• Upper folds vestibular (ventricular or false vocal)
• Lower folds true vocal folds/ vocal cords 31

32.  Laryngeal inlet (aditus)
The upper part of the laryngeal cavity is entered by the
laryngeal inlet (aditus laryngis)
Boundaries:
• Anteriorly: upper edge of the epiglottis
• Posteriorly: transverse mucosal fold b/w two
arytenoids (posterior commissure)
• Each side: Edge of a mucosal ridge (aryepiglottic
fold
• that runs b/w the side of the epiglottis and the
apex of the arytenoid cartilage.
32
Upper part of the laryngeal cavity

33. The aryepiglottic fold contains ligamentous and muscular
fibres.
• The ligamentous fibres represents free upper border of
the quadrangular membrane.
• The muscle fibres are continuations of the oblique
arytenoids.
The posterior parts has 2’s oval swellings :
• One above and in front > Cuneiform cartilage
• Other behind and below > Corniculate cartilage (Separated
by shallow vertical furrow that is continuous below with the
opening of the laryngeal ventricle)
• The midline groove between the two corniculate tubercles
is k/a interarytenoid notch.
33
 Aryepiglottic folds

34.  Laryngeal vestibule( introitus)
Vestibule is a clinical term that denotes the space between
the laryngeal inlet and vestibular folds.
It is wide above, narrow below, and higher anteriorly than
posteriorly.
Anterior wall : formed by the posterior surface of the
epiglottis,
• lower part of which bulges backwards a little (epiglottic
tubercle) .
Lateral walls : which are higher in front and shallow
behind, formed by the medial surfaces of the aryepiglottic
folds.
Posterior wall : consists of the interarytenoid mucosa
above the ventricular folds
34

35. Middle part of laryngeal cavity
• Smallest part , and extends from the rima vestibuli
above to the rima glottidis below.
• On each side it contains the vestibular folds, the
ventricle and the saccule of the larynx.
 Vestibular folds and ligaments
• The narrow vestibular ligament represents the
thickened lower border of the quadrangular membrane
• It is fixed in front to the thyroid angle below the
epiglottic cartilage and behind to the anterolateral
surface of the arytenoid cartilage above its vocal
process.
• With its covering of mucosa, it is termed the vestibular
(ventricular or false vocal) fold . 35

36.  Ventricle( sinus ) of larynx
• Slit b/w the vestibular and vocal folds.
• It opens into a fusiform recess on each side of the larynx
and extends upwards into the laryngeal wall lateral to the
vestibular fold, opening into the saccule.
 Saccule of larynx
• Pouch which ascends forwards from the ventricle,
between the vestibular fold and thyroid cartilage,
• It is conical, and curves slightly backwards;
• 60–70 mucous glands, sited in the submucosa, open onto its
luminal surface.
• The orifice of the saccule is guarded by a delicate fold of
mucosa, the ventriculosaccular fold.
• The saccule has a fibrous capsule that is continuous below
with the vestibular ligament. 36

37. Vocal folds (cords) and ligaments
• The deep and intermediate layers of vocal folds
forms the vocal ligament.
• Scaffolded/supported by : upper margin of conus
elasticus
• It stretches back on either side from the mid
level of the thyroid angle (anterior commissure)
to the vocal processes of the arytenoids.
• When covered by mucosa, it is termed the vocal
fold or vocal cord (fold is the preferred clinical
term)
• Anterior 3/5th : membranous part, posterior 2/5th:
cartilaginous part
• Each fold consists of five layers, namely
mucosa, lamina propria (three layers) and the
vocalis.
37

38. Reinkes edema
(smokers larynx / polypoidal vocal cord / chronic edema of vocal vord / pseudomyxomatous laryngitis)
• The mucous membrane is loosely attached throughout the
larynx, can accommodate considerable swelling.
• At the edge of the true vocal folds the mucosal covering
is tightly bound to the underlying ligament
• so that oedema fluid does not pass b/w the upper and lower
compartments of the vocal cord mucosa.
• Any tissue swelling above vocal cord exaggerates the
potential space (Reinke's space), causing accumulation
of ECF causing flabby swelling of the vocal cords
(Reinke's oedema).
• The oedema can persist d/t poor lymphatic drainage in
this region of the larynx.
• Vocal abuse (may be ), but the condition is nearly always
confined to smokers 38

39. Vocal fold nodules
• Chronic lesions of the vocal folds,
• Persistent overuse of the voice due to increase in vocal fold tension and more
forceful adduction.
• Normally develop at the point of maximum contact of the vocal folds to vocal
ligament, i.e. at the junction of the anterior 1/3rd and posterior 2/3rd of the vocal
ligament.
• Excessive trauma at this point (for e.g when singing with poor technique or forcing
the voice) Initially produces subepithelial haemorrhage or bruising
results in pathological changes such as subepithelial scarring (‘singer's
nodes' or ‘clergyman's nodes’).
• Nodules increase vocal fold mass and affect vocal fold closure:
• the persistent posterior glottal opening causes hoarseness, a breathy voice, reduced vocal
intensity and an inability to produce higher frequencies of vibration.
• These changes can cause a cycle in which increasing vocal effort is required by way
of compensation, and this exacerbates the problem. 39

40. Rima glottidis
• Fissure b/w vocal cords anteriorly and, arytenoid
cartilages and mucosa in b/w posteriorly,
• Behind by the mucosa b/w arytenoid cartilages at the
level of the vocal cords.
• Divided into 2’s regions
• Anterior intermembranous part: formed by the
underlying vocal ligament
• Posterior intercartilaginous part: formed by the
vocal processes of the arytenoid cartilages.
• It is the narrowest part of the larynx,
• Average length in adult males 23 mm vs adult
females 17 mm
• In resting state : vocal process- 8 mm apart
• Width and shape varies during respiration and
phonation.
40

41. Lower part of laryngeal cavity
• The lower part of the laryngeal cavity or, the subglottis or infraglottic cavity,
extends from the vocal cords to the lower border of the cricoid.
• In transverse section it is elliptical above and wider and circular below, and is
continuous with the trachea.
• Its walls are lined by respiratory mucosa, and supported by the cricothyroid ligament
above and the cricoid cartilage below.
• The walls of this part of the laryngeal cavity are said to be exponentially curved, a
feature that may serve to accelerate the airflow towards the glottis with the
minimum loss of energy
41

42. Paraluminal spaces
• A number of potential spaces lie between the laryngeal cartilages and the
ligaments and membranes that support them.
• Contains fats , lymphatics and vessels.
• Represent potential pathway of tumor spreads.
The two main spaces are:
• Pre-epiglottic and ,
• Paraglottic
42

43. Wedge-shaped space with the point of the wedge
inferiorly
Boundaries:
Anteriorly: Thyrohyoid ligament and hyoid bone
Posteriorly : Epiglottis.
Superiorly : Hyoepiglottic ligament
Inferiorly : Thyroepiglottic ligament
• The greater cornu of the hyoid bone forms its upper lateral border
Tumour may spread into this area via
• Through small perforations in the epiglottis
• Directly through the hyoepiglottic ligament.
• The pre-epiglottic space is continuous laterally with
the paraglottic space as no anatomical boundaries exist.
43
 Preepiglottic space: boyer’s space

44.  Paraglottic space
• Region of adipose tissue, contains the internal laryngeal
nerve, the laryngeal ventricle, and all or part of the laryngeal
saccule.
Boundaries
Laterally: By thyroid cartilage and thyrohyoid membrane
Superomedially: quadrangular membrane
Inferomedially : conus elasticus, and
Posteriorly: piriform fossa mucosa.
Inferior : lower border of the thyroid cartilage
• Supraglottic tumours may spread into paraglottic space, reach
the subglottis, or extend beyond the limits of the larynx.
• Ventricular tumours may obstruct mucus outflow from
saccule and cause expansion within the paraglottic space to
form a saccular cyst
44

45. Extrinsic muscles of larynx
45
Name origin function innervations Nerve supply
Thyro hyoid Oblique line of
thyroid
Inferior border of
greater cornu of
hyoid bone
Elevate
larynx(fixed hyoid)
Depress hyoid
(fixed larynx)
Hypoglossal (c1)
sternothyroid 1. Manubrium(po
sterior surface)
2. first costal
cartilage
(edge)
Oblique line of
thyroid
Depress the laryx Ansa Cervicalis
(c2,c3)
sternohyoid 1. Clavicle
2. Manubrium(po
sterior surface)
hyoid body (lower
edge)
Depress the larynx Ansa cervicalis
(c1,c2,c3)
 Infrahyoid group

46. Suprahyoid group
46
Name origin insertion function Nerve supply
Mylohyoid Mylohyoid line
in mandible
Midline raphe,
body of hyoid
bone
Hyoid-up and
anterior
Nerve to
mylohyoid ( Inf
alv branch-v3)
Geniohyoid Genial tubercle
in mandible
Body of hyoid
(upper border)
Hyoid-up and
anterior
Hypoglossal
(c1)
Stylohyoid Back of Styloid
process
(splits around
digastric)
Greater cornu
of hyoid
(upper border)
Retractor +
Elevator of
hyoid (for
swallowing)
Facial nerve
Digastric Digastric notch
in mastoid
process(medial
surface
Mandible
(lower border)
 Tendon ( to
hyoid by
fibrous
sling)
 Ant belly:
anterior and
up
 Post belly:
posterior
and up
Ant belly-
nerve to
mylohyoid
Post belly-
facial nerve

47. Stylopharyng
eus
Styloid
process
( medial
aspect)
Posterior
border of
thyroid
cartilage
Elevation of
larynx
Glossophary
ngeal nerve
Palatopharyng
eus
Palatine
aponeurosis
and hard
palate
Posterior
border of
thyroid
cartilage
Tilts larynx
forward
Accessory
nerve (
pharyngeal
plexus)
Salpingophary
ngeus
Eustachian
tube
Post border of
thyroid
cartilage
Elevates larynx Pharyngeal
plexus
47

48. Intrinsic muscles of larynx
 Opens and close the glottis
48
Name Origin Insertion Action
Posterior
cricoarytenoid
Lower + medial
surface of cricoid
lamina
muscular process of
arytenoid
Opens glottis/
Only abductor.
Lateral
cricoarytenoid
Lateral part of arch
of cricoid ( sup
border)
Muscular process of
arytenoid
Adduction
Transverse
arytenoid
(unpaired)
Post surface of
muscular process
and outer edge of
arytenoid
Cross over and
attach to same
point on other.
Adduction
Oblique arytenoid Posterior surface of
muscular process(
superficial to
transverse
arytenoid)
Apex of other
arytenoid
Adduction

49.  Controls tension in vocal folds
Name Origin Insertion Action
Thyroaytenoid(
vocalis)
Thyroid
prominence(
back) +
cricothyroid
ligament
Vocal process +
anterolateral
surface of body
of arytenoid)
Lower , shorten
and thickens the
vocal folds
(Relax vocal
cord)
Cricothyroid Lateral surface of
ant arch of
cricoid ( fans out
in 2 groups)
• Ant straight
fiber: thyroid
lamina
• Lower oblique
fiber: inferior
cornu of
thyroid
cartilage)
Tensors of vocal
fold
49

50.  Alter the shape of laryngeal inlet
Name Origin Insertion Action
Aryepiglotticus
(continuation of
oblique
arytenoid)
Muscular process
of arytenoid(
post. aspect)
Apex of opposite
arytenoid and
inserts into AE-
folds
Weak spinchter.
(Close laryngeal
inlet)
Thyroepiglotticus
(continuation of
thyroarytenoid)
Back of thyroid
prominence +
cricothyroid
ligament
Aryeepiglottic
fold
Open laryngeal
inlet
50

51. Vessels:
Superior laryngeal artery
• Arises from superior thyroid arteries
• Upper margin of the thyroid cartilage
• Accompanies the internal branch of the superior laryngeal nerve
through the thyrohyoid membrane and supply the larynx.
• Injured in endoscopic laser laryngeal surgery: as it enters
paraglottic space.
Inferior laryngeal artery
• Arise from the inferior thyroid branch of the thyrocervical trunk
of the subclavian artery
• At lower border of thyroid gland
• Together with the recurrent laryngeal nerve, ascends in the groove
between the esophagus and trachea
• Enters the larynx by passing deep to the margin of the inferior
constrictor muscle of the pharynx and supply the larynx.
51

52. Venous drainage
 Superior laryngeal veins
• drain into superior thyroid veins or facial veins, then to
the internal jugular veins
 Inferior laryngeal veins
• drain into inferior thyroid veins then to the left
brachiocephalic veins.
• Also, some veins drains to middle thyroid vein
finally to IJV.
Lymphatic drainage
Above vocal folds: Follow the superior laryngeal
vein--piercing thyrohyoid membrane and terminate in
Upper deep cervical nodes
Below vocal folds :lower deep cervical nodes, m/c
prelaryngeal or pretracheal L.N 52

53. Nerves
Superior laryngeal nerve
• Arises from Inferior vagal ganglion( medially)
• Receives branches from superior cervical sympathetic
ganglion
• Lateral to pharynx behind ICA at level of greater horn of
hyoid bone
• Then gives two branches – Smaller - External branch and Larger -
internal branch ( approximately 1.5 cm below the ganglion)
 Internal laryngeal nerve :
Passes forwards approx 7 mm before piercing the thyrohyoid
membrane, once pierced it divides into 2 parts.
• Upper: mucus membrane of lower pharynx, epiglottis,
vallecula, vestibule of larynx.
• Lower: descent in medial wall of pyriform fossa and
supplies AE folds and larynx to vocal folds
53

54.  External laryngeal nerve
• continues downwards and forwards on the lateral surface
of the inferior constrictors (gives small branches)
• It passes beneath the attachment of sternothyroid to the
oblique line of the thyroid cartilage and supplies
cricothyroid.
Superior laryngeal nerves ends by piercing the inferior
constrictor of pharynx and anastomosis with ascending
branch of RLN’s (Galens anastomosis=purely sensory)
• Galens anastomosis: Internal branch of SLN and RLN’s
• Human communicating nerve: ext branch of SLN and
distal portion of RLN’s 54

55. Recurrent laryngeal nerve
55
Right RLN:
Leaves vagus as it crosses superficial to rt subclavian artery and loops under the artery ,
ascending in the tracheoesophageal groove to enter larynx.
Left RLN’s:
Originate in vagus as it crosses aortic arch, then pass under the aortic arch and ligamentum
arteriosum to reach tracheoesophageal groove.
In neck: follow same path, pass upwards accompanied by laryngeal branch of inferior
thyroid artery.
• They pass deep to lower border of inferior constrictors muscles and enters behind the cricothyroid
joint.
 Motor : to all intrinsic muscles of thyroid except cricothyroid ( Ext branch of SLN)
 Sensory : to all laryngeal mucosa below vocal folds ( above vocal folds by superior
laryngeal nerve—internal branch) + carry afferent fibers from stretch receptors from
laryngeal mucosa

56. • Relation ship b/w RLN and ITA is variable.
• In front or, behind or, may pass b/w terminal branches of
artery .
Right side
• Equal chance of nerve being in any of these 3 locations
Left side
• More likely behind/ posterior to artery
• Right RLN : Extensive course, palsy far more common
• Vulnerable to pressure from aortic arches, intrathoracic masses
• Also during thoracic and thyroid surgery
56

57. Non-recurrent laryngeal nerve
Very rare anomaly(0.3 to 1.8%)
• aberrant course, not descending in thorax (hence, non-recurrent)
• Right NRLN arises directly from the vagus nerve trunk
high up in the neck and enters the larynx close to the
inferior pole of the thyroid gland.
• NRLNs on Right side: Often exclusive
• It is always associated with an abnormal origin of the
right subclavian artery from the aortic arch on the left
side.
• NRLNs on the Left side
• reported a few times
• all of them accompanied by other significant
pathologies such as situs inversus and right sided aortic
arch. 57

58. 3 types:
• Type-1: courses closely to the superior thyroid
vessels.
• Type-2A: courses parallel to the inferior thyroid
artery and transversely above the artery.
• Type-2B: courses parallel to the inferior thyroid
artery, and transversely between branches of or
under the inferior thyroid artery
58
MEDINA RUÍZ et.al. Int. J. Morphol., 36(1):149-158, 2018
• If unrecognized, a NRLN nerve may be
susceptible to injury during surgery.
• It may also potentially be compressed by small
tumours of the thyroid gland
Embryology
• Aortic arch derivatives

59. RLN paralysis (U/L: 1/3rd asymptomatic, B/L: stridor,
dyspnoea)
• Unilateral / bilateral : median / paramedian ( all intrinsic
muscles are paralysed except cricothyroid)
Explained by:
Semons law: abductors 1st paralysed than adductors
Wagner and grossman hypothesis: keeps the cord in
paramedian position due to its adductor function
SLN paralysis ( weak voice and aspiration)
• U/L : askew position of VC and anesthesia above vocal folds
• B/L : bilateral cricothyroid paralysis and B/l anesthesia above
vocal fold
Combined RLN+ SLN: cadaveric position + total anesthesia( if
B/L)
59
Laryngeal Paralysis

60. Infant larynx
60
Basis v Infants adults
Lumen short , narrow and
funnel-shaped
cylindrical shape
Extent C2/C3 (when elevated:
c1)
C3 to C6
Epiglottis Omega-shaped Leaf shaped
Laryngeal cartilages Softer and more pliable strong
Superior notch/ laryngeal
prominence
Not marked marked
Arytenoid cartilage More prominent Less prominent
Aryeepiglottic folds Disproportionally large Relatively small
Ventricle Small than adult Relatively larger
Saccule Larger than adult Relatively smaller
Narrowest part Subglottis Glottis

61. Trachea
• D-shaped, tubular structure, formed of cartilage +
fibromuscular membrane, lined internally by mucosa.
• The Anterolateral portion-- incomplete rings of cartilage,
and the posterior aspect by a flat muscular wall(trachealis)
• T5 (easy marking -manubrium, 2nd costal cartilage :
divides into right and left principal (pulmonary) bronchi.
• It lies approximately in median plane, but its point of
bifurcation is usually a little to the right.
• The trachea is mobile, can rapidly alter in length; during
swallowing(upwards) and deep inspiration -- the
bifurcation may descend at level of 6th thoracic vertebra .
Diameter:
• Inspiraton: increases (vs decreases in expiration)
• Transverse diameter >AP diameter : 20mm vs 15 mm in
adult male .
61
10–11 cm
C6
T5 upper
border
• 2 rings/cm of trachea
• Each ring : 4mm in
length
• 18-22 rings

62. Relations of trachea
Cervical part of the trachea ( 5cm, cricoid to T1)
Anterior relations
• Skin , superficial and deep cervical fasciae
• Sternohyoid and sternothyroid muscles
• The 2nd -4th tracheal cartilages are crossed by the isthmus
of the thyroid gland).
Posterior relations -oesophagus
Lateral relations
• The paired lobes of the thyroid gland, which descend to
the 5th – 6th tracheal cartilage,
• Common carotid, IJV, Inferior thyroid artery, vagus nerve,
cervical sympathetic ganglion.
• Tracheoesophageal groove: RLN’s
62

63. Thoracic part of the trachea ( T1 to T5)
Anterior relations
• 1st costal cartilage ,manubrium sterni, the thymic
remnants and the inferior thyroid vein.
• The left common carotid artery, left brachiocephalic
veins and aortic arch
• deep cardiac plexus and some lymph nodes
Posterior relations -The oesophagus
Lateral relations
• Right : right lung and pleura, right brachiocephalic
vein, superior vena cava, right vagus nerve and azygos
vein.
• Left : Arch of the aorta, left common carotid and left
subclavian artery, vagus and left RLN’s.
63

64. Artery :
• Upper third: Inferior thyroid artery,
• Lower third: Bronchial artery
Veins :
• Tracheal vein---thyroid plexus
Lymphatic drainage :
• Into the pretracheal and paratracheal lymph nodes and the deep cervical nodes
64

65. Carina and bronchus
• Trachea bifurcations and narrow slightly at carina( t4 level)
• Right and left main bronchus(T5)
65
Rt bronchus Lt bronchus
5cm in length 5.5 cm
Wider , shorter and more vertical
Transverse diameter
17 +/- 4 male , 15+/- 4 female
Narrower (by 2-3mm )
Angle with trachea : 20-30 degree Average : 45 degree

66. Right main bronchus
• Lies b/w: pulmonary vein above and azygous vein(below)
• Right main bronchus(1cm): from carina at 12-20mm
 Right upper lobe bronchus:
• Apical, posterior and anterior (total: 3)
 Right middle lobe bronchus: 2.5cm down bronchus
intermedius
• Lateral and medial segment
Right lower lobe bronchus:
• Superior, Medial basal, anterior basal, lateral basal,
posterior basal ( total : 5)
66

67. Left main bronchus
Crosses anterior to esophagus, thoracic duct, descending
aorta—travelling inferior to aortic arch
• Left pulmonary artery first lies anterior and then
superior to left main bronchus—terminates in left hilum
at T6 as upper and lower lobe bronchi
Left upper bronchus: apical ,posterior and anterior
segmental, superior and inferior lingual (Total: 5)
Left lower bronchus: Superior, lateral basal, posterior
basal , medial basal (Cardiac) and anterior basal segments
(total: 5)
67

68. Histology of tracheobronchial tree
Trachea: ciliated, pseudo-stratified squamous epithelium
with goblet cells
Bronchus
• Principal bronchus and lobar : same as trachea
• Tertiary or segmental bronchus: columnar epithelium,
glands becomes less.
• Terminal bronchioles: cuboidal cells, sparse mucus
glands, no cartilage
• Respiratory bronchioles: cuboidal cells with no mucus
glands.
68

69. Arterial supply:
• Broncial artery( carina to respiratory bronchioles)
Venous drainage:
• Bronchial vein
• Superficial and deep---terminates into zygous vein on right
• Superior intercostal vein or accessory hemiazygous vein
Lymphatic drainage:
• Pulmonary nodes
69

70. 70
• Short tubular collection of various structures enters
and leave
• Covered by sleeve of mediastinal pleura( visceral
pleura)
• Below the hilum the mediastinal pleura extends as
a double layer - pulmonary ligament
• Continuous above with the pleura around hilar
structures and below it ends in free sickle-shaped
border
Root of lungs/ hilum

71. 71
Anterior to posterior:
Anterior plexus
Pulmonary vessels( artery –superior, veins-
inferior)
Bronchi and bronchial vessels
Nerves, and
Lymphatics
Posterior plexus
• Right lung vs left lung hilum: additional
eparterial bronchus superior most. Right lung and its relations

72. 72
Anterior to posterior:
Anterior plexus
• Pulmonary vessels( artery –most
superior, vein- inferior)
• Bronchi and bronchial vessels
• Nerves, and
• Lymphatics
Posterior plexus
Left lung and its relations

73. ….Thank you
73

74. References
• Scott brown 6th and 8th edition
• Grays anatomy 41st edition
• Grays anatomy 1st student edition
• Keith l. Moore clinical anatomy
• Langmann embryology
• Various internet sources
74