The LarynxThe Larynx(Anatomy and physiology)(Anatomy and physiology)

The First Affiliated Hospital of Sun –Yatsen University

Aiyun jiang

The LarynxThe Larynx the meeting place of voice,

swallow and airway. The larynx is an arrangement

of several cartilages held together by ligaments and muscles. It is connected above with the hypopharynx and below with the trachea.

Out side the cartilagous framework are the strap muscles of the neck.

Behind the larynx are the third,fourth, fifth and sixth cervical vertebrae.

The Larynx(Anatomy)The Larynx(Anatomy) CONTENTSFramework Cartilages (*cricoid) (Joints) Muscles(*abductor) Membranes and ligaments* Laryngeal cavity Nerve Blood supplyLymphatic drainage

cartilagescartilages There are four cartilages:

thyroid, cricoid,

arytenoid, epiglottic. (1)Thyroid:the largest and

most prominent .The

thyroid cartilage shields

the intrinsic part of the

larynx anteriorly and laterally.

It consists of two flat lamina which fused in the midline anteriorlly and open posteriorly. Extending upward from each lamina is the superior cornu , and extending downward is the inferior cornu. At its top, is the thyroid notch

..(2)Cricoid:The cricoid

looks like a signet

ring,with a broad ,

flat, posterior lamina.

* It is the only complete

ring of cartilage in the

larynx. And it differs

from all other tracheal rings that it forms a complete circle. So it is the only rigid area in the respiratory tree. It is very important in maintaining the normal lumen of respiratory tract

..

(3)Arytenoid. are a

pair of small

pyramid-shape

cartilages . Perch

on top of the

lamina of cricoidEach Arytenoids cartilage has two processes: a

vocal process, to which the posterior end of vocal ligaments is attached, and a muscular process, to which the intrinsic laryngeal muscle is attached.

..(4)Epiglottic cartilage:a pear-

shaped,curved plate of cartilages covered by mucosa on both surfaces.

The superior half is above the level of hyoid bone and projects freely into the oropharynx.

jointsjoints There are just two pair of joints in the larynx,the

cricoarytenoid(CA) and cricothyroid(CT),all the internal adjustments of the vocal cords are medeated through them.

CA: Enables the vocal cords to drawn away from the midline(abduction) or brought to midline(adduction).

CT: It is important in pitch control and provides a mechanism for regulating the

lengthening of the vocal folds. When these two cartilages are pulled towards each other, the vocal folds are lengthened, when towards apart,the vocal folds are shortened.

..

Muscles(1)Muscles(1) (1)Abductor Muscles:posterior cricoarytenoid

muscle(PCA).

The major muscles responsible for the arytenoid rocking

and gliding apart, and for the abduction of the vocal

folds.

(2)Adductor muscles:

1) interarytenoid muscles(IA): Their action is to pull the

upper tips of the arytenoids together.

2)lateral cricoarytenoid muscles(LCA): adduct the

arytenoids and are also able to squeeze the anterior tips of

the vocalprocesses tightly in a condition of medial

compression.

Muscles(2)Muscles(2) (3)Tensor Muscles: Cricothyroid muscles(CT). Originate

from the front of the cricoid cartilages and insert into

the thyroid cartilage.

*Just remember PCA is responsible for abduction of VC , IA and LCA are responsible for adduction of VC,CT is responsible for tense of VC

Membranes and LigamentsMembranes and Ligaments(1)Conus elasticus:Its free edge thickens to form the

vocal ligaments (which lie between the arytenoid and thyroid cartilages ) and False vocal folds ( which is above the true vocal folds)

(2)Thyrohyoid membrane:between the hyoid bone and the thyroid cartilage.

(3)Cricothyroid membrane:between the cricoid and thyroid cartilages.At this point the lumen of the airway is closest to the skin of the neck and therefore, most accessible in an emergency.

..

Laryngeal cavityLaryngeal cavity(1)supraglottis: the part of

the larynx above the level

of the vocal cords.

It consists of the epiglottis,

the aryepiglottic folds,

the ventricular band and

the laryngeal ventricle.(2)glottis:the space between the vocal cords.(3)subglottis: the part of the larynx below the level of the vocal cords.

..

Blood supply Blood supply

The superior thyroid artery through its branch, superior laryngeal artery

The inferior thyroid artery through its branch, inferior laryngeal artery

Provide most of the blood supply to the larynx

..

Nerve supplyNerve supplythe entire laryngeal nerve supply is from the vagus(1)recurrent laryngeal nerves provide the motor supply to the intrinsic muscles of the larynx and the sensory innervation to the subglottis.(2)Superior laryngeal nerve are the motor nerves of the cricothyroid muscles and provide the sensory supply to the

supraglottis and glottis. .

Lymphati drainageLymphati drainage(1)the supraglottis:is richly supplied with lymphatic

vessels which drain into the ipsilateral midjugular lymph nodes.

(2)the vocal cords have few lymphatic spaces and poor lymphatic drainage.

(3)the subglottis is richly supplied with lymphatic vessels which empty into the paratracheal nodes and the Delphian node.

so carcinoma metastasis of the supraglottis may occur in early stage of the tumor

carcinoma metastasis of the glottis is not common if the tumor doesn’t involve the supraglottis and subglottis

Chracters of larynx in childrenChracters of larynx in children1 、 location: high

2 、 cartilages:soft3 、 pultaceous connect tissue , richly supplied

with lymphatic vessels4 、 lumen(space): narrow

5 、 curved epiglottis6 、 short VC, high pitch

Physiology of the LarynxPhysiology of the Larynx

1 Protection:To protect the lower respiratory passages(cough reflex, sphincteric action—three levels)

2 Respiration: To conduct air to and from the lungs3 phonation: To function as a vocal organ4 To fix the chest in heavy physical effort