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Anatomy of Larynx
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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 function2. Voice production
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.
EMBRYOLOGY Primitive larynx: cranial end of
laryngo-tracheal groove
Laryngeal mucosa: endoderm
Laryngeal cartilages & muscles: mesenchyme
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
STRUCTURE OF LARYNX Laryngeal framework is
formed by –
1. Cartilages2. Membranes & ligaments3. Muscles of larynx
LARYNGEAL CARTILAGES Paired
Arytenoid cartilage Corniculate cartilage Cuneiform cartilage
Unpaired: Thyroid cartilage Cricoid cartilage Epiglottis
THYROID CARTILAGE Hyaline cartilage
Largest.
Encloses the larynx anteriorly and laterally
Two alae
Ossification.
THYROID CARTILAGE Internal surface gives attachments to – Thyro-epiglottic ligament, paired vocal and vestibular ligaments and Vocalis, Thyro-arytenoid and Thyro-epiglotticus muscles.
CRICOID CARTILAGE Hyaline cartilage
StrongestShape: Signet ringLamina – flat portion
Only complete annular support of the larynx
Articulates with Inferior cornu of the thyroid cartilage
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.
EPIGLOTTIS (contd.)
ARYTENOID CARTILAGES Mostly hyaline cartilage Smaller in size Responsible for opening and closing
of the larynx Shape: pyramidal
ARYTENOID CARTILAGES Anterior Vocal process -
receives the attachment of the mobile end of each VC
Lateral Muscular process
Articulation Cricoarytenoid
joint
CORNICULATE CARTILAGES Fibro elastic Cartilages of Santorini Small cartilages above the
arytenoid and in the aryepiglottic folds
CUNEIFORM CARTILAGES
Fibro elastic cartilages
Cartilages of Wrisberg
Elongated pieces of small yellow elastic cartilage in the aryepiglottic folds
TRITICEOUS CARTILAGES Cartilago
triticea
Small elastic cartilage in the lateral thyrohyoid ligament
LARYNGEAL LIGAMENTS Extrinsic Thyrohyoid membrane and
ligaments
Cricothyroid membrane and ligaments
Cricotracheal ligament
Hyo-epiglottic ligament
LARYNGEAL LIGAMENTS Intrinsic
Quadrangular membrane
Conus elasticus (cricovocal membrane)
Median cricothyroid ligament
Vocal Ligament
Thyroepiglottic ligament
EXTRINSIC LIGAMENTSThyrohyoid membraneMedian Thyrohyoid ligament
– thickened median portion
Lateral thyrohyoid ligament
– thickened posterior border
- where cartilago triticea is often found
EXTRINSIC LIGAMENTSThyrohyoid membrane
pierced on each side by:
1. Superior laryngeal vessels
2. Internal branch of superior laryngeal nerve
EXTRINSIC LIGAMENTS
Cricothyroid membrane and ligaments
May be pierced for emergency tracheotomy (cricothyrotomy)
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.
HYO-EPIGLOTTIC LIGAMENT
INTRINSIC LIGAMENTS Elastic membrane
Divided into upper and lower parts by the ventricle of the larynx
Forms the fibrous framework of larynx.
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
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
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
INTRINSIC LIGAMENTS OF LARYNX
CAVITY OF THE LARYNX Divided into 3 parts:
Vestibule
Ventricle
Sub glottic space
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
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
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)
RIMA GLOTTIDIS
CAVITY OF THE LARYNXFalse Cords (ventricular bands)
Anteriorly: angle of the thyroid cartilage
Posteriorly: bodies of the arytenoid cartilage
CAVITY OF THE LARYNXTrue cordsVoice productionProtection of lower respiratory tractAnteriorly,: angle of thyroid cartilage
Posteriorly : vocal processes of the arytenoid cartilages
Enclose vocal ligament and a major part of the vocalis muscle
VOCAL VOCAL CORDSCORDS 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
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
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.
JOINTS OF LARYNX Cricothyroid joint
1. Synovial joint
2. Formation -inferior horn of thyroid cartilage and a facet in the cricoid
Two types movements:
RotationGliding
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
MUSCLES OF LARYNX Extrinsic
Intrinsic
EXTRINSIC MUSCLES OF LARYNX Attach larynx to surrounding
structures.
DIRECT ELEVATORS: Stylopharyngeus, Palatopharyngeus, Salpingopharyngeus, Thyrohyoid
INDIRECT ELEVATORS : Mylohyoid, Geniohyoid , Stylohyoid & Digastric
DEPRESSORS: Sternothyroid, Sternohyoid,Omohyoid
Depressor Depressor musclesmuscles
OriginOrigin InsertionInsertion ActionAction
Sternohyoid Sternohyoid manubrium manubrium of sternum of sternum and medial and medial end of end of clavicleclavicle
oblique line of oblique line of the thyroid the thyroid cartilagecartilage
depresses/depresses/stabilizes the stabilizes the hyoid bonehyoid bone
Omohyoid Omohyoid superior superior border of border of scapula near scapula near the the suprascapulsuprascapular notchar notch
inferior inferior border of border of hyoid bonehyoid bone
depresses, depresses, retracts and retracts and steadies the steadies the hyoid during hyoid during swallowing swallowing and speakingand speaking
SternothyroiSternothyroid Muscle d Muscle
Superior Superior attachment: attachment: oblique line oblique line of thyroid of thyroid cartilage.cartilage.
Inferior Inferior attachment: attachment: posterior posterior surface of surface of manubrium of manubrium of sternum.sternum.
It depresses It depresses the hyoid the hyoid bone and bone and larynx larynx
Primary Primary Elevator Elevator musclesmuscles
OriginOrigin InsertionInsertion ActionAction
StylopharyngeStylopharyngeusus
styloid styloid process process of of temporal temporal bonebone
posterior and posterior and superior superior borders of borders of thyroid thyroid cartilage with cartilage with palatopharyngpalatopharyngeus muscleeus muscle
elevates the elevates the pharynx and pharynx and larynx and larynx and expands the sides expands the sides of the pharynxof the pharynx
SalpingopharySalpingopharyngeus ngeus
cartilagincartilaginous part ous part of the of the auditory auditory tubetube
blends with blends with palatopharyngpalatopharyngeus muscleeus muscle
elevates the elevates the pharynx and pharynx and larynx and opens larynx and opens the orifice of the the orifice of the auditory tube auditory tube during swallowingduring swallowing
PalatopharyngPalatopharyngeuseus
hard hard palate palate and and palatine palatine aponeuroaponeurosissis
lateral wall of lateral wall of pharynxpharynx
tenses the soft tenses the soft palate and pulls palate and pulls the walls of the the walls of the pharynx pharynx superiorly, superiorly, anteriorly and anteriorly and medially during medially during swallowingswallowing
SecondarSecondary y
Elevator Elevator musclesmuscles
OriginOrigin InsertionInsertion ActionAction
GeniohyoGeniohyoid id
inferior inferior mental spine mental spine of mandibleof mandible
body of hyoid body of hyoid bonebone
pulls the hyoid bone pulls the hyoid bone anterosuperiorly, and anterosuperiorly, and shortens the floor of the shortens the floor of the mouth and widens the mouth and widens the pharynxpharynx
DigastricDigastrics s
anterior anterior belly-belly-digastric digastric fossa of fossa of mandible, mandible, posterior posterior belly-mastoid belly-mastoid notch of notch of temporal temporal bonebone
intermediate intermediate tendon to tendon to body and body and greater horn greater horn of hyoid boneof hyoid bone
depresses the mandible depresses the mandible and raises the hyoid and raises the hyoid bone. Also, it steadies bone. Also, it steadies the hyoid bone during the hyoid bone during swallowing and swallowing and speakingspeaking
MylohyoiMylohyoid d
mylohyoid mylohyoid line of line of mandiblemandible
raphe and raphe and body of hyoid body of hyoid bonebone
elevates the hyoid elevates the hyoid bone, floor of the mouth bone, floor of the mouth and the tongue during and the tongue during swallowing and swallowing and speakingspeaking
StylohyoiStylohyoid d
styloid styloid process of process of the temporal the temporal bonebone
body of hyoid body of hyoid bonebone
elevates and retracts elevates and retracts the hyoid bone, thereby the hyoid bone, thereby elongating the floor of elongating the floor of the mouththe mouth
EXTRINSIC MUSCLES OF LARYNX
EXTRINSIC MUSCLES OF LARYNX (contd.)
INTRINSIC MUSCLES OF LARYNX Interarytenoid muscle Transverse Oblique
Post. Cricoarytenoid m.
Lateral cricoarytenoid m.
Thyroarytenoid m.
Cricothyroid m.
Muscles Controlling Movements of the Vocal CordsIntrinsic Intrinsic
MusclesMusclesOriginOrigin InsertionInsertion ActionAction
Posterior cricoarytenoid
posterior posterior surface of surface of the lamina the lamina of the of the cricoid cricoid cartilagecartilage
muscular muscular process of process of the arytenoid the arytenoid cartilagecartilage
Abduct vocal Abduct vocal cordcord
Interarytenoid m., transverse
posterior posterior surface of surface of the the arytenoid arytenoid cartilagecartilage
posterior posterior surface of the surface of the contralateral contralateral arytenoid arytenoid cartilagecartilage
Closes Closes posterior part posterior part of rima of rima glottidis by glottidis by approximatinapproximating arytenoid g arytenoid cartilagescartilages
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
MUSCLES CONTROLLING THE LARYNGEAL INLETIntrinsic Intrinsic MusclesMuscles
OriginOrigin InsertionInsertion ActionAction
Interarytenoid m., oblique
muscular muscular process of process of the the arytenoid arytenoid cartilagecartilage
posterior posterior surface of the surface of the contralateral contralateral arytenoid arytenoid cartilage, near cartilage, near its apexits apex
draws draws arytenoid arytenoid cartilages cartilages together, together, adducting the adducting the vocal folds vocal folds (closure of (closure of glottis)glottis)
Thyroepiglottic
inner surface inner surface of the of the thyroid thyroid cartilage cartilage near the near the laryngeal laryngeal prominenceprominence
lateral surface lateral surface of the of the epiglottic epiglottic cartilagecartilage
draws the draws the epiglottic epiglottic cartilage cartilage downwarddownward
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
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
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
ARTERIAL SUPPLY Area above vocal cords Superior
laryngeal artery
Area below vocal cords Inferior
laryngeal artery
VENOUS DRAINAGE Upper Larynx
Superior laryngeal vein
Lower Larynx Inferior
laryngeal vein
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
INDIRECT LARYNGOSCOPY