8. HYOID BONE
U-SHAPED.
It is situated just above the thyroid
cartilage.
BODY- Quadrilateral , anterior & posterior
surface with superior & inferior borders .
SUPERIOR BORDER- Hyoepiglottic &
Thyrohyoid membrane.
It is attached to mandible & skullbase by
stylohyoid ligament , digastric, mylohyoid,
stylohyoid , geniohyoid , hyoglossus muscles
hence helping in raising larynx during
deglutition & phonation .
9. IMPORTANCE
In suspected case of homicide , fracture of hyoid strongly indicates
throttling & strangulation .
During excision of thyroglossal cyst , sistrunk operation reduces
recurrence rate.
Serves as a site of access to supraglottic larynx & pharynx
In Tracheal resection & anastomosis , tension free closure of distal
airway .
Physiological functions – breathing, swallowing , speech & to keep
airway open during sleep.
OSA - more inferiorly placed hyoid bone (hyoid suspension
surgery).
10. THYROID CARTILAGE
Hyaline cartilage, largest cartilage of larynx.
2 Lamina ; angle of 90 degree (male-adam’s apple ) & 120 degree (female).
Ala ossification- begins at 25yrs , completes by 65 yrs.
11. External surface- oblique line -----> thyrohyoid, sternothyroid and inferior
constrictor muscles.
The inner surface also gives attachment to the thyroepiglottic, vestibular, and
vocal ligaments, as well as the thyroarytenoid and the vocalis muscles
13. IMPORTANCE
Cartilage is divided in midline to expose endolarynx for various
procedures (eg.partial laryngectomy , laryngotracheoplasty,
arytenoidectomy ).
Cricothyroidotomy – emergency ventilation
Fracture
14. CRICOID CARTILAGE
only complete cartilagenous ring in the
upper airway.
Signet ring shape.
Narrow ARCH anteriorly , broad LAMINA
posteriorly.
15. Cricothyroid joints (on the posterior lateral aspect) and
cricoarytenoid joints (on the superior lateral aspect).
Inferiorly, it is related to the first tracheal ring by
cricotracheal ligament.
The cricothyroid ligament and lateral cricoarytenoid
muscles are attached anteriorly, along the superior surface
of the cricoid arch.
Posteriorly - posterior cricoarytenoid muscles.
The external and lateral surface of the arch - cricothyroid
muscle.
16.
17.
18. IMPORTANCE
Injury to cartilage – perichondritis & sublottic stenosis.
Cricothyroidotomy – through median cricothyroid ligament.
To avoid permanent laryngeal stenosis , it shouls be converted to
tracheostomy within days .
Surgical approaches to to repair lon standing subglottic stenosis
involve expansion of circumference of cricoid ring.
19. EPIGLOTTIS
leaf-like, yellow, elastic cartilage forming anterior wall of
laryngeal inlet.
It is attached inferiorly to the thyroid cartilage, just below the
thyroid notch in the midline, by the thyroepiglottic ligament.
To the hyoid bone anteriorly by the hyoepiglottic ligament.
20.
21. Aryepiglottic folds
Posterior surface- numerous small pits into which mucus
glands project.
Anterior surface -mucous membrane superiorly and forms the
posterior wall of the vallecula.
Posterior surface of epiglottis is concavoconvex—concave
above but convex below forming a bulge called tubercle of
epiglottis, which obstructs view of anterior commissure when
examining larynx by indirect laryngoscopy
22.
23.
24. IMPORTANCE
ACUTE EPIGLOTTITIS – airway obstruction in
children.
Carcinoma involvement.
During swallowing , closes laryngeal inlet.
26. Muscular process - directed laterally to give attachment to
posterior cricoarytenoid and lateral cricoarytenoid muscles .
Vocal process - directed anteriorly, giving attachment to vocal
cord .
Medial surface - covered with mucous membrane and form the
lateral boundary of the posterior glottis.
Posterior surface - covered by the transverse arytenoid muscle.
27. IMPORTANCE
Cricoarytenoid fixation may occur from arthritis or perichondritis
(intubation injury etc.) & limit vocal fold mobility.
Cricoarytenoid subluxation during blind intubation .
Arytenoidectomy through external or endoscopic approach may
alleviate arytenoid fixation or paralysis.
28. CORNICULATE CARTILAGE (SANTORINI)
two small conical nodules of elastic fibrocartilage which
articulate through a synovial joint with the apices of the
arytenoid cartilages.
They are situated in the posterior part of the aryepiglottic fold.
two small elongated flakes of fibroelastic cartilage, one in each
margin of the aryepiglottic fold.
CUNEIFORM CARTILAGE ( WRISBURG )
29. JOINTS
2 in no. ; simple synovial joints .
CRICOTHYROID JOINT –
Each is formed by the inferior cornua of thyroid cartilage with a
facet on the cricoid cartilage.
Movements are across the transverse axis passing through these
joints.
30. CRICOARYTENOID JOINT –
formed between the base of arytenoid and a facet on the upper
border of cricoid lamina.
Two types of movements occur in this joint:
(i) rotatory, in which arytenoid cartilage moves around a
vertical axis, thus abducting or adducting the vocal cord.
(ii) gliding , in which one arytenoid glides towards the other
cartilage or away from it, thus closing or opening the posterior
part of glottis.
31.
32. LIGAMENTS & MEMBRANES
EXTRINSIC MEMBRANES AND LIGAMENTS
(a) Thyrohyoid membrane - It connects thyroid cartilage to
hyoid bone. It is pierced by superior laryngeal vessels and
internal laryngeal nerve.
(b) Cricotracheal membrane - It connects cricoid cartilage to the
first tracheal ring.
(c) Hyoepiglottic ligament - It attaches epiglottis to hyoid.
(d) Thyrohyoid ligaments
(e) Cricotracheal ligament
33. INTRINSIC MEMBRANES AND LIGAMENTS
(a) Cricovocal membrane - It is a triangular fibroelastic membrane.
Its upper border is free and stretches between middle of thyroid angle to
the vocal process of arytenoid and forms the vocal ligament
Its lower border attaches to the arch of cricoid cartilage.
From its lower attachment the membrane proceeds upwards and medially
and thus, with its fellow on the opposite side, forms conus elasticus
where subglottic foreign bodies sometimes get impacted.
(b) Quadrangular membrane - It lies deep to mucosa of aryepiglottic folds
It stretches between the epiglottic and arytenoid cartilages.
Its lower border forms the vestibular ligament which lies in the false
cord.
34. (c) Cricothyroid ligament - The anterior part of cricothyroid
membrane is thickened to form the ligament and its lateral part
forms the cricovocal membrane.
(d) Thyroepiglottic ligament - It attaches epiglottis to thyroid
cartilage.
38. INTRINSIC
(a) Acting on vocal cords :
Abductors: Posterior cricoarytenoid
Adductors: Lateral cricoarytenoid, Interarytenoid (transverse
arytenoid), Thyroarytenoid (external part)
Tensors: Cricothyroid, Vocalis (internal part of thyroarytenoid
(b) Acting on laryngeal inlet :
Openers of laryngeal inlet: Thyroepiglottic (part of
thyroarytenoid)
Closers of laryngeal inlet: Interarytenoid (oblique part),
Aryepiglottic (posterior oblique part of interarytenoids)
39.
40.
41.
42.
43.
44.
45.
46.
47. INTERIOR OF LARYNX
LARYNGEAL INLET –
Above & in front by free margin of epiglottis.
Laterally by aryepiglottic fold.
Posteriorly by interarytenoid region.
EPITHELIUM –
Most of the larynx is lined by pseudo stratified ciliated columnar
'respiratory' -type epithelium.
The upper half of the posterior surface of the epiglottis, the
upper part of the aryepiglottic fold, the posterior glottis & the
vocal folds are covered with nonkeratinizing stratified squamous
epithelium..
52. Vestibule - It extends from laryngeal inlet to vestibular folds. Its
anterior wall is formed by posterior surface of epiglottis; sides by
the aryepiglottic folds and posterior wall by mucous membrane
over the anterior surface of arytenoids.
Inferior limit of supraglottis –
CLINICALLY – imaginary horizontal plane passing through
apex of laryngeal ventricle .
ANATOMICALLY – superior arcuate line where squamous &
respiratory epithelium meet .
53. Marginal zone-
Suprahyoid epiglottis
Aryepiglottic folds
It is recognised because of
Aggressive clinical behaviour of cancer arising in this area .
Lack of embryological separation from adajacent hypopharynx
& it carries worse prognosis among laryngeal cancers .
Mucous glands are abundant in saccule & periarytenoid area .
Early lymphatic spreads of supraglottic cancer is because of
rich vascularity & lymphatics associated with these glands.
54. GLOTTIS
TRUE VOCAL CORDS
ANTERIOR COMMISSURE
POSTERIOR COMMISSURE
The glottis lies between the false and true vocal cords
which cover the vestibular and vocal ligaments, respectively.
Vocal fold – extends from middle of the angle of the thyroid
cartilage to the vocal process of the arytenoid cartilages and
underlying them is the upper border of the conus elasticus.
55. Each fold -
Superficial layer of nonkeratinizing, stratified
squamous epithelium
Lamina propria – 3 distinct layers.
The superficial layer (Reinke's space) - fibrous
substance with similar characteristics to gelatin.
The intermediate layer - elastic fibres and the deep
layer collagen fibres.
The intermediate and deep layers make up the vocal
ligament.
The vocalis muscle, which forms the main body of the
vocal fold, lies lateral and deep.
56.
57. Vestibular folds - two thick folds of mucous membrane each
enclosing a narrow band of fibrous tissue, the vestibular ligament,
which is the lower border of the upper quadrilateral membrane.
It is fixed in front at the angle of the thyroid cartilage just below
the attachment of the epiglottic cartilages and behind the
anterolateral surface of the arytenoid cartilage just above the vocal
process
58. Glottis (rima glottidis) - It is the elongated space between vocal
cords anteriorly, and vocal processes and base of arytenoids
posteriorly .
Anteroposteriorly, glottis is about 24 mm in men and 16mm in
women. It is the narrowest part of laryngeal cavity.
Anterior two-thirds of glottis are formed by membranous cords
while posterior one-third by vocal processes of arytenoids.
59. Ventricle (sinus of larynx) - It is a deep elliptical space between
vestibular and vocal folds, also extending a short distance
above and lateral to vestibular fold.
The saccule is a diverticulum of mucous membrane which
starts from the anterior part of ventricular cavity and extends
upwards between vestibular folds and lamina of thyroid
cartilage.
When abnormally enlarged and distended, it may form a
laryngocele—an air containing sac which may present in the
neck.
There are many mucous glands in the saccule, which help to
lubricate the vocal cords.
60.
61. LOWER LIMIT OF GLOTTIS – Controversial
Horizontal plane passing 1cm below free margin of vocal
cords at anterior commissure & 0.5cm below posterior
commissure .
Horizontal plane 20 mm below anterior commissure .
62. SUBGLOTTIS
Extends inferior to glottis to lower border of cricoid
cartilage .
Rare site of origin of cancer
Highest incidence of extralaryngeal spread
proximity of cricothyroid membrane .
rich postcricoid lymphatics .
63. SPACES OF LARYNX
REINKE’S SPACE –
Submucosal space along most of the length of free edge of true
vocal cord
Extending from superior arcuate line to inferior arcuate line.
Infront by anterior commissure.
Behind by vocal process of arytenoid.
Oedema of this space causes fusiform swelling of the
membranous cords (Reinke’s oedema).
Blood vessels & lymphatics are almost absent preventing early
spread of cancers.
64.
65. PRE-EPIGLOTTIC SPACE OF BOYER
Wedge shaped space.
ANTERIOR – Throhyoid membrane
Thyroid cartilage above thyroepiglottic ligament
• SUPERIOR – Hyoepiglottic ligament
Mucosa of vallecula
• POSTERIOR- Infrahyoid epiglottis
Thyroepiglottic ligament
• CONTENT – FAT
66.
67. It is continuos laterally with paraglottic space deep to
quadrangular membrane & superior to ventricle.
CLINICAL IMPORTANCE -
Cancer on laryngeal surface of infrahyoid epiglottis
spreads readily into this space.
68. PARAGLOTTIC SPACE (tucker’s space)
ANTEROLATERALLY – Thyroid cartilage , cricothyroid
membrane .
SUPEROMEDIALLY – Quadrangular membrane .
INFEROMEDIALLY – Conus elasticus .
POSTERIORLY – Anterior reflection of pyriform sinus mucosa.
It encompasses the laryngeal ventricles and saccules .
69.
70. CLINICAL IMPORTANCE
Space is situated lateral to ventricles; tumor involving ventricle
invades the space & later spreads transglottically.
Space blends with pre-epiglottic space anterosuperiorly.
Lateral supraglottic tumors can travel lateral to ventricle along
inner surface of thyroid ala & thus spread subglottically.
Pyriform sinus malignancy paraglottic space endolarynx
resulting fixation of hemilarynx .
71. PAEDIATRIC LARYNX
STRUCTURE DESCRIPTION
SHAPE Small & conical
POSITION High in the neck level of glottis being opposite to C3 or C4
at rest and reaches C1 or C2 during swallowing.
This high position allows the epiglottis to meet soft palate
and make a nasopharyngeal channel for nasal breathing
during suckling. The milk feed passes separately over the
dorsum of tongue and the sides of epiglottis, thus allowing
breathing and feeding to go on simultaneously.
CARTILAGES Soft & collapse easily.
EPIGLOTTIS Omega shaped with a furled petiole
72. STRUCTURE DESCRIPTION
THYROID It is flat. It also overlaps the cricoid cartilage and is in turn
overlapped by the hyoid bone. Thus cricothyroid and
thyrohyoid spaces are narrow and not easily discernible as
landmarks when performing tracheostomy.
Neither the superior notch nor the laryngeal prominence are
as marked as they are in the adult.
CRICOID Diameter of cricoid cartilage is smaller than the size of
glottis, making subglottis the narrowest part. It has a
bearing in the selection of paediatric endotracheal tube.
ARYTENOID More prominent and the aryepiglottic folds are
disproportionally large.
Covers significant portion of the posterior glottis.
VOCAL CORDS 4–4.5 mm long, which is relatively shorter.
76. NERVE SUPPLY
• SENSORY :
Supraglottis & upper surface of vocal cords – Internal branch of
superior laryngeal nerve .
Subglottis & lower surface of vocal cords – Recurrent laryngeal
nerve.
• MOTOR :
INTRINSIC – All muscles except cricothyroid : recurrent
laryngeal nerve .
Cricothyroid – External branch of superior laryngeal nerve.
GALEN’S ANASTOMOSIS - Superior & Recurrent laryngeal
nerve .
77.
78. BLOOD SUPPLY
ARTERIAL -
Superior laryngeal branch of superior thyroid artery.
Inferior laryngeal branch of inferior thyroid artery .
Cricothyroid branch of superior thyroid artery.
VENOUS –
Via superior and inferior laryngeal veins which run parallel to the
laryngeal arteries and are tributaries of the superior and inferior
thyroid veins respectively.
The superior thyroid vein drains into the internal jugular vein, and
the inferior thyroid vein usually into the left brachiocephalic vein.
79.
80.
81. LYMPHATIC DRAINAGE
Supraglottic larynx above the vocal cords is drained by lymphatics,
which pierce the thyrohyoid membrane and go to upper deep
cervical nodes (level II, III).
Infraglottic larynx below the vocal cords is drained by lymphatics
which pierce cricothyroid membrane and go to prelaryngeal and
pretracheal nodes and hence to lower deep cervical and mediastinal
nodes.
Some vessels pierce through cricotracheal membrane and drain
directly into lower deep cervical nodes.
Glottis - ‘watershed area’- with poor lymphatics .
Anterior commissure – prelaryngeal (delphian node)
84. PHYSIOLOGY OF LARYNX
FUNCTIONS :
Protection of tracheobronchial tree
Respiration
Phonation
To increase intrathoracic pressure ( effort closure )
Swallowing (deglutition)
Coughing
85. SWALLOWING (Deglutition)
Primary function – to prevent food & liquid entering airway .
Sphincteric action of aryepiglottic folds , true & false vocal cords
which occurs simultaneously with elevation of larynx .
ORAL STAGE
Voluntary
control
PREPARATORY
TRANSPORT
PHARYNGEAL
STAGE
Reflex activity
SWALLOWING
OESOPHAGEAL
STAGE
86. ORAL STAGE : Food bolus is manipulated by tongue &
broken down by teeth before being propelled towards
oropharynx.
PHARYNGEAL STAGE : reflex activity which is initiated as
the bolus reaches the back of the tongue.
During this phase, the glottis is closed by adduction of the
arytenoids and contraction of the lateral cricoarytenoid
muscles, false vocal folds and true vocal folds.
3-Tier system –
1) Closure of laryngeal vestibule by contraction of aryepiglottic
& interarytenoid muscles.
2) Ventricular bands approximation .
3) Adduction of vocal cords by adductors .
87. Epiglottis covers the laryngeal entrance and directs the bolus in two
parts into the valleculae and the pyriform sinuses.
The two columns of the divided bolus meet at the upper border of
the cricopharyngeus muscle which relaxes to allow the bolus to
enter the oesophagus.
Rapid laryngeal elevation occurs during the pharyngeal phase of the
swallow and appears to be essential for normal swallowing.
This manoeuvre produces a drop in pressure and transient negative
pressure in the cricopharyngeal sphincter as the bolus passes from
the pharynx into the oesophagus.
88. A mid-sagittal section of the head
and neck showing the location of
the major structures involved in
swallowing.
A. Hard palate
B. Soft palate
C. Nasopharynx
D. Pharyngeal isthmus
E. Oropharynx
F. Laryngopharynx
G. Cricoid cartilage
H. Thyroid cartilage
I. Hyoid bone
J. Laryngeal inlet.
89. Oral and pharyngeal stages of
a normal swallow:
(a) oral phase, food is
reduced and the bolus
prepared
(b) bolus is moved to the
posterior part of the tongue
(c) bolus contacts
the trigger points in the
oropharynx and the
pharyngeal phase is initiated
(d) bolus is moved past the
closed larynx
(e) Bolus enters the
oesophagus.
90. COUGHING
The process by which material is expelled from the airway.
Preceded by rapid inspiration
forceful closure of both the vocal and vestibular folds
Air pressure builds up below the adducted folds as the
diaphragm ascends spasmodically
until the folds separate explosively and mucus or foreign
material is expelled
91.
92. EFFORT CLOSURE
Laryngeal structure has evolved in order to contain intrathoracic
pressure, so as to provide a stable fulcrum for the upper limbs.
Expiratory effort against a closed glottis is known as the Valsalva
manoeuvre.
During any form of exertion involving use of the arms, the vocal
folds are firmly adducted preventing expulsion of air and collapse
of the chest walls, thus providing a fixed origin for the arm and
shoulder muscles.
To increase intrathoracic pressure : Fixation of chest by glottic
closure essential for straining , climbing etc.
97. • Immediately before phonation, the vocal folds
rapidly abduct to allow the intake of air.
• Vocal folds are adducted by the contraction of
the lateral cricoarytenoid muscles.
• The vocal note is generated by pulmonic air
(air from the lungs) as it is exhaled between
the adducted vocal folds.
98. Subglottic air pressure increases below the adducted vocal
folds until it reaches a level which overcomes their resistance
and blows them apart, thus setting in motion the vibratory
cycles which result in phonation.
101. As the increased subglottic pressure overcomes the
resistance of the adducted vocal folds at the onset of
phonation, the vocal folds peel apart from their inferior
border.
When they finally separate at their superior margin, a puff
of air is released.
The resulting negative pressure in the glottis, caused by
the Bernoulli effect, results in the vocal folds closing
rapidly as they are sucked together, the inferior vocal fold
margins closing first.
102. The Bernouilli effect is a drop in pressure dependent on
particle velocity.
In relation to the vocal tract,when air passes from one large
space to another (e.g. from lung to pharynx), through a
constriction (the glottis), the velocity will be greatest and the
pressure least at the site of the constriction.
As a result of the drop in pressure at the glottis, the vocal fold
mucosa is drawn into space between the vocal folds.
Contact between the vocal folds increases until the subglottic
air pressure is high enough to blow the vocal folds apart again,
and the cycle recommences.
103.
104.
105. COVER/ BODY THEORY
Each cycle of adduction, separation and recoil is the manifestation
of a mucosal wave travelling from the inferior to the superior
surface of each vocal fold.
The process by which this undulating wave of movement of the
mucous membrane occurs is dependent on what is known as the
cover/body theory
Vocalis muscle provides the firm body of the vocal fold over
which the mucous membrane cover of the vocal fold is blown by
the expiratory air stream.
106.
107. Periods of vocal fold contact & lack of contact in
one vibratory cycle
PHASE DESCRIPTION
CLOSING The vocal folds begin to close rapidly from their lower
margin.
CLOSED The medial edges of the vocal folds are in full contact.
OPENING The vocal folds begin to separate from their lower
margin and gradually peel apart.
The superior margin remains in contact until the end of
this phase.
OPEN The vocal folds are separated, the longest part of a
normal vibratory cycle.
108.
109. VOCAL REGISTERS
CHARACTERISTICS OF VOCAL FOLD ADDUCTION AND
VIBRATION
Hollien's suggestion that registers should be defined in terms of
laryngeal behaviour, rather than in acoustic terms, as registers are
governed by the degree of contraction of the vocalis muscle.
LOFT REGISTER
MODAL REGISTER
PULSE REGISTER
They describe the vibratory pattern of the vocal folds and the
acoustic parameters being produced.
110. REGISTERS FEATURES VOCAL
FOLDS
FO
RANGE (Hz)
LOFT
REGISTER
(Falsetto )
Highest vocal
frequencies
Thin, Tense,
Lengthened,
Minimal
vibration
275 - 1100
MODAL
REGISTER
(Chest,head,
middle, heavy
voice)
Range of
fundamental
frequencies
(speaking, singing
etc.)
Complete
Adduction
100 - 300
PULSE
REGISTER
(Vocal fry,
glottal fry ,
creaky voice)
Lowest range of
vocal frequencies ;
laryngeal output is
perceived as
pulsatile
Long closed
phase
20 - 60
111. NEUROANATOMY OF PHONATION
Depends on integrated functioning of CNS & PNS.
PAG (Periaqueductal grey matter) – midbrain
The motor activity for vocalization appears to be integrated
through a projection from the PAG to a column of neurones,
known as the nucleus retroambigualis(NRA) which plays a
significant role in generating respiratory pressure and laryngeal
adduction, which occurs in both vocalization and vegetative
manoeuvres, such as coughing.
112. Precentral gyrus of motor cortex of both cerebral hemispheres.
Medulla oblongata
Cortico-bulbar tract (part of
pyramidal system) / DIRECT
ACTIVATION TRACT
Ipsilateral vagus nucleus Contralateral vagus nucleus
Nucleus ambiguus ( reticular formation of medulla )
Also contains IX & XI CN elements
Ipsilateral vagus Contralateral vagus
SUPPLY LARYNGEAL MUSCULATURE THROUGH
THEIR BRANCHES
Some fibres Some fibres decussate
113. The indirect neurones of the pyramidal tract have multiple
offshoots and synapses with the basal ganglia and reticular
formation in the brainstem.
They appear to contribute to temporospatial orientation while the
direct system is related to discrete movement.
The frontobulbar portions of the pyramidal tracts connect with
cranial nerves IX to XII (as well as I to VIII), thus controlling
articulation, phonation and respiration.
The extrapyramidal system (the basal ganglia in the cerebral
hemispheres,the substantia nigra and subthalamic nucleus in the
upper brainstem, the cerebellum and the thalamus among other
structures.
114. The extrinsic and intrinsic muscles of the larynx are under
voluntary cortical control.
They are responsible for the prephonatory tuning which precedes
phonation and is followed by the phasic, tonic and volitional
contractions and also maintenance of length, tension, bulk and
position of the vocal folds.
The phonatory modulations which take place in speech - finely
coordinated system of reflex controls over the laryngeal muscles
and over the abdominal and intercostal muscles that maintain
subglottic air pressure at appropriate levels.
115. LARYNGEAL MECHANORECEPTORS
Wyke postulated that mechanoreceptors are found in three sites:
1) The mucosal lining of the larynx (subglottic mucosal
mechanoreceptors):
The corpuscular nerve endings in the subglottic mucous membrane
covering the surface of the vocal folds - sensitive to the stimuli of
muscle stretch, air pressure level, liquid and touch.
They discharge impulses into the afferent fibres of the vagus.
116. 2) The capsules of the articulatory joints (articular
mechanoreceptors):
The existence and function of this group remain controversial.
3) The extrinsic and laryngeal muscles (myotatic mechanoreceptors):
The tone of the laryngeal muscles depends on the myotatic reflex,
which is a function of the muscle spindles.
The laryngeal muscles contain a large number of muscle spindle.
117. FUNCTIONS :
Sensitive to muscle stretch and airflow pressures.
Some are involved in protecting the airway while others contribute
to the control of phonation.
Reflex closure of the larynx is triggered by tactile receptors in the
glottic and supraglottic mucosa, which evoke reflex contraction of
the laryngeal muscles.
Receptors in the subglottic mucosa elicit laryngeal closure and
cough.
118. REFERENCES
Scottt brown’s otorhinolaryngology, head & neck surgery
Cummings otolaryngology & head & neck surgery (6th edition)
Hazarika textbook of ear,nose ,throat & head & neck surgery
(3rd edition)
Dhingra – disaeases of ear , nose, throat & head & neck surgery
(6th edition)
Gray’s anatomy (40th edition)
Snell’s clinical anatomy (9th edition)
Netter’s atlas of human anatomy ( 6th edition)
Editor's Notes
Laterally, the cricoid cartilage receives the lowermost fibers of the inferior constrictor muscle and the semicircular fibers of the cricopharyngeus muscle.
Vertical ridge in posterior surface of lamina – upper fibres of oesophagus
Between these two processes, the anterolateral surface is irregular and divided into two fossa by a crest running from the apex. The upper triangular fossa gives attachment to the vestibular ligament and the lower to the vocalis and lateral cricoarytenoid muscles.
