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Anatomy of the larynx by arijit
1.
2. STRUCTURE OF THE
LARYNX
• Larynx is our VOICE BOX.
• The Larynx extends from Laryngeal inlet
above to the lower border of Cricoid cartilage
below.
• Functions of Larynx :
1. Protective function
2. Voice production
3.
4. INFANTILE LARYNX
Lumen narrower
More funnel-shaped
Narrowest part is the junction of the sub-
glottic larynx with the trachea
Cartilages are much softer and hence
collapses more easily on forced inspiration.
Placed more high up.
6. EMBRYOLOGY
Epiglottis- hypobranchial eminence
Upper part of thyroid cartilage-4th
arch
Lower part of thyroid cartilage, cricoid,
corniculate, cuneiform, intrinsic muscles-6th
arch
Upper part of body& lesser cornu of hyoid-2nd
arch
Lower part of body & greater cornu of hyoid-3rd
arch
7. STRUCTURE OF LARYNX
Laryngeal framework is formed by –
1. Cartilages
2. Membranes & ligaments
3. Muscles of larynx
13. EPIGLOTTIS
Fibro elastic cartilage
Leaf-shaped structure
Petiole – small narrow
stalk like portion of
the epiglottis
attached to the
thyroid cartilage.
Contains a tubercle on
its posterior surface.
15. ARYTENOID CARTILAGES
Mostly hyaline cartilage
Smaller in size
Responsible for opening and closing of the
larynx
Shape: pyramidal
16. ARYTENOID CARTILAGES
Anterior
Vocal process -
receives the
attachment of
the mobile end of
eachVC
Lateral
Muscular process
Articulation
Cricoarytenoid
joint
18. CUNEIFORM CARTILAGES
Fibro elastic cartilages
Cartilages of Wrisberg
Elongated pieces of
small yellow elastic
cartilage in the
aryepiglottic folds
25. EXTRINSIC LIGAMENTS
Crico tracheal Ligament
Attaches the cricoid
cartilage to the first
attached ring
Hyo-epiglottic Ligament
Connects the anterior
surface of epiglottis
with Hyoid bone.
27. INTRINSIC LIGAMENTS
Elastic membrane
Divided into upper
and lower parts by the
ventricle of the larynx
Forms the fibrous
framework of larynx.
28. INTRINSIC LIGAMENTS
Quadrangular membrane
Upper part of the elastic
membrane
Boundaries
Epiglottis , arytenoid,
corniculate cartilage,
false cord
Forms part of wall
between upper pyriform
sinus and laryngeal
vestibule
29. INTRINSIC LIGAMENTS
Conus elasticus (cricovocal membrane)
Lower part of elastic membrane
Composed mainly of yellow elastic tissue
Median cricothyroid ligament – thickened
anteior part
Vocal Ligament – free upper edge
30. INTRINSIC LIGAMENTS
Boundaries
Inferior: superior border of cricoid
cartilage
Superoanterior: deep surface of angle
thyroid cartilage
Superoposterior: vocal process of
arytenoid cartilage
Thyro-epiglottic ligament
32. CAVITY OF THE LARYNX
Divided into 3 parts:
Vestibule
Ventricle
Sub glottic space
33. CAVITY OF THE LARYNX
Vestibule – boundaries:
Anterior: posterior
surface of epiglottis
Posterior: interval
between arytenoid
cartilages
Lateral: inner surface
of ary-epiglottic folds
and upper surfaces of
the false cord
34. CAVITY OF THE LARYNX
• Ventricle
• Saccule – conical pouch at anterior part of the
ventricle. Lies between Inner surface of thyroid
cartilage and false cord. It has numerous mucous
glands opening into the surface of its lining
mucosa for lubricating the vocal cords.
• SUBGLOTTIC SPACE
35.
36. RIMA GLOTTIDIS
Space between free
margin of true cords
Two portions –
Anterior or Inter-
membranous (3/5
th)
Posterior or Inter-
cartilagenous (2/5
th)
38. CAVITY OF THE LARYNX
False Cords (ventricular
bands)
Anteriorly: angle of
the thyroid cartilage
Posteriorly: bodies of
the arytenoid cartilage
39. CAVITY OF THE LARYNX
True cords
Voice production
Protection of lower respiratory tract
Anteriorly,: angle of thyroid cartilage
Posteriorly : vocal processes of the
arytenoid cartilages
Enclose vocal ligament and a major part of
the vocalis muscle
40. VOCAL CORDSVOCAL CORDS
The lamina propria consists
of three layers. The most
superficial consists of fibrous
substance similar to gelatin,
and is loosely attached to
the underlying vocal
ligament
The intermediate layer
consists of elastic fibres, and
the deep layer is formed of
collagen fibres; these two
layers collectively form the
vocal ligament
Fibres of the vocalis muscle
form the fifth layer of the
vocal folds
41. POTENTIAL TISSUE SPACES
REINKE`S SPACE:-
Between superficial
layer of lamina propria
and mucosa of vocal
cords.
PARAGLOTTIC SPACE:-
between the
membranes of the
larynx and the thyroid
cartilage
42. PRE-EPIGLOTTIC SPACE
Pre-epiglottic space of boyer:-
• Between hyoid & thyrohyoid membrane
anteriorly and infrahyoid epiglottis Posteriorly.
• Fat filled
• Sparse blood supply, so relatively radio-
resistant
• Invasion of this space- Stage T3 in TNM
classification.
43. JOINTS OF LARYNX
Cricothyroid joint
1. Synovial joint
2. Formation -inferior
horn of thyroid
cartilage and a facet
in the cricoid
Two types movements:
Rotation
Gliding
44. JOINTS OF LARYNX
Crico-arytenoid jt.-
1. Synovial joint
2. Formation-base of
arytenoid and facet on the
upper border of cricoid
lamina
3. Types of movement-
A) Rotatory along vertical
axis, causing abduction &
adduction of vc
b) gliding
47. DepressorDepressor
musclesmuscles
OriginOrigin InsertionInsertion ActionAction
SternohyoidSternohyoid manubrium ofmanubrium of
sternum andsternum and
medial end ofmedial end of
clavicleclavicle
oblique line of theoblique line of the
thyroid cartilagethyroid cartilage
depresses/stabilizesdepresses/stabilizes
the hyoid bonethe hyoid bone
OmohyoidOmohyoid superior bordersuperior border
of scapula nearof scapula near
thethe
suprascapularsuprascapular
notchnotch
inferior border ofinferior border of
hyoid bonehyoid bone
depresses, retractsdepresses, retracts
and steadies theand steadies the
hyoid duringhyoid during
swallowing andswallowing and
speakingspeaking
SternothyroidSternothyroid
MuscleMuscle
SuperiorSuperior
attachment:attachment:
oblique line ofoblique line of
thyroidthyroid
cartilage.cartilage.
InferiorInferior
attachment:attachment:
posterior surfaceposterior surface
of manubrium ofof manubrium of
sternum.sternum.
It depresses theIt depresses the
hyoid bone andhyoid bone and
larynxlarynx
48. PrimaryPrimary
ElevatorElevator
musclesmuscles
OriginOrigin InsertionInsertion ActionAction
StylopharyngeusStylopharyngeus styloidstyloid
process ofprocess of
temporaltemporal
bonebone
posterior andposterior and
superior borders ofsuperior borders of
thyroid cartilagethyroid cartilage
withwith
palatopharyngeuspalatopharyngeus
musclemuscle
elevates the pharynxelevates the pharynx
and larynx and expandsand larynx and expands
the sides of the pharynxthe sides of the pharynx
SalpingopharyngeuSalpingopharyngeu
ss
cartilaginouscartilaginous
part of thepart of the
auditoryauditory
tubetube
blends withblends with
palatopharyngeuspalatopharyngeus
musclemuscle
elevates the pharynxelevates the pharynx
and larynx and opensand larynx and opens
the orifice of thethe orifice of the
auditory tube duringauditory tube during
swallowingswallowing
PalatopharyngeusPalatopharyngeus hard palatehard palate
and palatineand palatine
aponeurosisaponeurosis
lateral wall oflateral wall of
pharynxpharynx
tenses the soft palatetenses the soft palate
and pulls the walls ofand pulls the walls of
the pharynx superiorly,the pharynx superiorly,
anteriorly and mediallyanteriorly and medially
during swallowingduring swallowing
49. SecondarySecondary
ElevatorElevator
musclesmuscles
OriginOrigin InsertionInsertion ActionAction
GeniohyoidGeniohyoid inferior mentalinferior mental
spine of mandiblespine of mandible
body of hyoidbody of hyoid
bonebone
pulls the hyoid bonepulls the hyoid bone
anterosuperiorly, and shortensanterosuperiorly, and shortens
the floor of the mouth andthe floor of the mouth and
widens the pharynxwidens the pharynx
DigastricsDigastrics anterior belly-anterior belly-
digastric fossa ofdigastric fossa of
mandible,mandible,
posterior belly-posterior belly-
mastoid notch ofmastoid notch of
temporal bonetemporal bone
intermediateintermediate
tendon to bodytendon to body
and greater hornand greater horn
of hyoid boneof hyoid bone
depresses the mandible anddepresses the mandible and
raises the hyoid bone. Also, itraises the hyoid bone. Also, it
steadies the hyoid bone duringsteadies the hyoid bone during
swallowing and speakingswallowing and speaking
MylohyoidMylohyoid mylohyoid line ofmylohyoid line of
mandiblemandible
raphe and body ofraphe and body of
hyoid bonehyoid bone
elevates the hyoid bone, floorelevates the hyoid bone, floor
of the mouth and the tongueof the mouth and the tongue
during swallowing and speakingduring swallowing and speaking
StylohyoidStylohyoid styloid process ofstyloid process of
the temporalthe temporal
body of hyoidbody of hyoid
bonebone
elevates and retracts the hyoidelevates and retracts the hyoid
bone, thereby elongating thebone, thereby elongating the
52. INTRINSIC MUSCLES OF
LARYNX Interarytenoid muscle
Transverse
Oblique
Post. Cricoarytenoid m.
Lateral cricoarytenoid
m.
Thyroarytenoid m.
Cricothyroid m.
53. Muscles Controlling Movements of
the Vocal Cords
IntrinsicIntrinsic
MusclesMuscles
OriginOrigin InsertionInsertion ActionAction
Posterior
cricoarytenoid
posteriorposterior
surface of thesurface of the
lamina of thelamina of the
cricoid cartilagecricoid cartilage
muscular processmuscular process
of the arytenoidof the arytenoid
cartilagecartilage
Abduct vocal cordAbduct vocal cord
Interarytenoid m.,
transverse
posteriorposterior
surface of thesurface of the
arytenoidarytenoid
cartilagecartilage
posterior surfaceposterior surface
of theof the
contralateralcontralateral
arytenoidarytenoid
cartilagecartilage
Closes posteriorCloses posterior
part of rimapart of rima
glottidis byglottidis by
approximatingapproximating
arytenoidarytenoid
cartilagescartilages
54. Muscles Controlling Movements Of
The Vocal Cords
Intrinsic
Muscles
Origin Insertion Action
Lateral Crico-
arytenoid
Lateral part of
upper border of
arch of Cricoid
Muscular
process of
Arytenoid
Adductor of
the vocal
cord.
Crico-thyroid Lower border
and lateral
surface of
Cricoid
Inferior cornu
and lower
border of
Thyroid
cartilage.
Tensor of
Vocal cords
55.
56.
57. MUSCLES CONTROLLING THE
LARYNGEAL INLET
Intrinsic MusclesIntrinsic Muscles OriginOrigin InsertionInsertion ActionAction
Interarytenoid
m., oblique
muscular processmuscular process
of the arytenoidof the arytenoid
cartilagecartilage
posterior surface ofposterior surface of
the contralateralthe contralateral
arytenoid cartilage,arytenoid cartilage,
near its apexnear its apex
draws arytenoiddraws arytenoid
cartilages together,cartilages together,
adducting the vocaladducting the vocal
folds (closure offolds (closure of
glottis)glottis)
Thyroepiglottic inner surface ofinner surface of
the thyroidthe thyroid
cartilage near thecartilage near the
laryngeallaryngeal
prominenceprominence
lateral surface oflateral surface of
the epiglotticthe epiglottic
cartilagecartilage
draws the epiglotticdraws the epiglottic
cartilage downwardcartilage downward
58.
59.
60. MUCOUS MEMBRANE
Stratified squamous epith.: over vocal cords and
upper part of vestibule of larynx
Ciliated columnar epith.: remainder of the cavity
Mucous glands:
Ventricles and sacculi
Posterior surface of epiglottis
Margins of aryepiglottic folds
Reinke’s layer of connective tissue: No glands and no
lymph vessels
61. NERVE SUPPLY
Inferior (recurrent) laryngeal n.
Motor – all intrinsic laryngeal muscles
of SAME side (except cricothyroid)
and interarytenoid muscle of BOTH
sides
Sensory – areas below the glottis
62.
63.
64. NERVE SUPPLY
Supplied by Vagus nerve:
Superior laryngeal n.
Internal branch (sensory) – areas
above the glottis
External branch (motor and sensory)
Motor – Cricothyroid muscle
Sensory – Anterior infraglottic
larynx at level of cricothyroid
membrane
65. ARTERIAL SUPPLY
Area above vocal cords
Superior laryngeal
artery
Area below vocal cords
Inferior laryngeal
artery
67. LYMPHATIC DRAINAGE
Supraglottis:-
upper deep cervical
nodes
Glottis:-
sparse, except for a
small lymph node in the
cricothyroid membrane
delphian node
Subglottis:-
lower deep cervical and
mediastinal lymph
nodes via prelaryngeal
and paratracheal nodes
Location: C4-C6
Upper portion of larynx, which is continuous w/pharynx is almost triangular in shape
Lower portion leading to trachea presents a circular appearance
This cartilage has two alae/wing which meet anteriorly, they form a depression called the THYROID NOTCH before meeting at the protruberance of the Adam’s apple or laryngeal prominence. Posteriorly, each wing has a superior cornu (extending upward about 2 cm) and inferior cornu (articulates w/cricoid cartilage below; ONLY DIRECT ARTICULATION, all others being maintained by muscles or ligaments)
Ossifies at 20-30 years of age, begins in the inferior margin and progress cranially
Ossifies after the thyroid cartilage, first part to be calcified being the superior portion (w/c can be mistaken for a foreign body) Calcification progresses caudally.
Lamina – flat portion of the ring llocated posteriorly and extends upward to form the POSTERIOR border of the larynx
Only complete annular support of the laryngeal skeleton; preservation essential to maintain the enclosed airways.
Level: Adult: C6-C7 Children: C3-C4
Posterolaterally, cricoid articulates w/ Inferior cornu of the thyroid cartilage, which forms true synovial joints (permit a ROCKING action of the cricoid cartilage on the thyroid cartilage and a slight anteroposterior SLIDING motion (cricoid cart. Supports the 2 arytenoid cartilages on posterosuperior aspect)
Attached to the INSIDE of the thyroid cart. Anteriorly and projects upward and backward above the laryngeal opening.
Petiole – small narrow portion of the glottis that is attached to the thyroid cart.
The epiglottis is attached to the hyoid bone by the hyoepiglottic ligament.
To the posterior part of the tongue by the median glossoepiglottic fold.
To the sides of the pharynx by the lateral glossoepiglottic folds.
To the thyroid cartilage by the thyroepiglottic ligament.
The mucous membrane covering the epiglottis is reflected to the posterior part of the tongue as one medial and two lateral glossoepiglottic folds. Between these folds are depressions called epiglottic valleculae.
Calcify at the 3rd decade (Hyoid – ossifies fr. 6 centers shortly after brith, complete by 2 years of age)
Arytenoids rest on the upper edge of the cricoid lamina at the posterior border of the larynx
Mobile end of VC – posterior
Lateral promincence of each arytenoid cart. Is known as Muscular process, becoz of insertion site of numerous muscles
Articulation of arytenoids with cricoid cart. Is at the CRICOARYTENOID JOINT, w/c permits a WIDE range of motion in 3 directions
When calcified, it can be mistaken as a foreign body in soft tissue Xray films
Thyrohyoid m&L –attach thyroid cart. To hyoid bone
Obvious from its name, the CT m&L connect the thyroid and cricoid cart.
Cricothyrotomy – little fear of bleeding; however becoz of proximity to the vocal cords, this space shld not be used for prolonged intubation, as scar tissue may be produced.
Elastic m.-lies beneath the laryngeal mucosa, Fibrous framework of the larynx
Ventricle of the larynx (ventricle of Morgagni)
Quad membrane - Boundaries: extending from LATERAL margin of epiglottis to arytenoid and corniculate cart., and INFERIORLY to the false cord.
Median cricothyroid ligament – thickened anteior part of conus elasticus
Vocal Ligament – is d free upper edge of the conus elasticus (strongest part), forms the framework of the vocal cord
Thyroepiglottic ligament – ataches epiglottis to the thyroid cartilage
Divided into 3 parts by 2 folds of mucous membrane, namely the true and false cords.
Vestibule – lies bet. Inlet and edges of false cords
Ventricle (Morgagni) - Deep, spindle-shaped recess bet. True and false cords, lined by a mucous membrane that is covered externally by thyroarytenoid muscle
Subglottic space – lies bet. True VC and lower border of cricoid cartilage
Saccule – conical pouch that ascends fr anterior part of the ventricle, lies bet. Inner surface of thyroid cartilage and false cord; has numerous mucous glands open into the surface of its lining mucosa for lubricating the vocal cords.
Glottis – space bet. Free margin of the true VC, opening/aperture
Posterior glottic chink in adult: 18-19mm; New born: 4mm; total glottic chink in a newborn: 14mm2
False cords – upper set of two horizontal folds on each side of the laryngeal cavity.
TVC – covering epith. Is closely bound down to underlying vocal ligament, blood supplu here is poor hence the pearly white appearance of the vocal cords in life.
Intrinsic muscles, all are paired except Interarytenoid m.
Larynx moves up during swallowing, down after.
The extrinsic muscles move the larynx as a whole. The infrahyoid muscles or straps (omohyoid, sternohyoid, and sternothyroid) are depressors of the hyoid bone and the larynx, whereas the suprahyoid muscles (stylohyoid, digastric, mylohyoid and geniohyoid) and the stylopharyngeus are elevator of the hyoid bone and larynx.
Sternothyroid Muscle - a thin muscle located deep to the sternohyoid muscle, and is shorter and wider than it.
Inferior attachment: posterior surface of manubrium of sternum.
Superior attachment: oblique line of thyroid cartilage.
Innervation: C2 and C3 by a branch of the ansa cervicalis.
It depresses the hyoid bone and larynx after it has been elevated by muscles during swallowing and vocal movements.
It also pulls the thyroid cartilage away from the hyoid bone, thereby opening the laryngeal orifice.
Muscles controlling Movements of the Vocal Cords
ELN –ext laryngeal branch from SLN(CN X)
ILN –inferior laryngeal nerve from RLN (CN X)
Muscles controlling the laryngeal inlet
Margins of aryepiglottic folds – none on he free edges of the vocal cords
Reinke’s layer of connective tissue – lies immediately under the epith. Of larynx and superficial to elastic layer. NO GLANDS BENEATH AND NO LYMPH VESSELS IN IT.
RLN – longer course on L than R, L: turns around arch of aorta, R: around subclavian artery
Nucleus ambiguus – somatic motor nucleus of CN IX, X, XI
- supplied by PICA (fr. Veterbal a.) and AICA (fr. Basilar artery)