LARYNX

LARYNX 

1.INTRODUCTION:

                Larynx is also called it has “voicebox” ,which extends from the root of the tongue and hyoid bone to the trachea.

2.SITUATION:

                It lies infront of the laryngopharynx at the level of 3^rd ,4^th ,5^th and the 6^th cervical    vertebrae.

3.SHAPE:     APPLE SHAPE

                Upto the puberty there is little difference between two sexes ,there after it grows larger in male compare to females,which explains prominence of the “adam`s apple ” and it gives deeper voice.

4.STRUCTURES ASSOSCIATED WITH THE LARYNX.

§  Superiorly – The Hyoid Bone And The Root Of The Tongue.

§  INFERIORLY – It Is Continous With The Trachea.

§  ANTERIORLY-The Muscles Attached To The Hyoid Bone And The Muscles Of The Neck.

§  POSTERIORLY- The Laryngophaynx And  3^rd To 6^th Cervical Vertebrae.

§  Laterally- The Lobes Of The Thyroid Gland.

5.structure:

CARTILAGES:

                The larynx is composed of many irregularly shaped cartilages attatched to each other by ligaments and membranes.

They are

                Hyaline cartilage

v  1 thyroid cartilage

v  1 cricoid cartilage.

v  2 arytonoid cartilages

Elastic fibrocartilage

v  1 epiglottis.

The thyroid cartilage:

v  This is the most prominent & consists of two flat pieces of hyaline cartilage or laminae,fused anteriorly , forming the laryngeal prominence( ADAM`S APPLE).

v  Immediately above the laryngeal prominence  the laminae are separated ,forming a V shaped notch called it has THYROID NOTCH.

v  In posterior region the thyroid cartilage is incomplete and the posterior border of each lamina is extended to to form 2 process called the SUPERIOR and INFERIOR CORNU.

v  The upper part of the thyroid cartilage is lined with stratified squamous epithelium .

v  The lower part lined with ciliated columnar epithelium like the trachea.

v  The thyroid cartilage forms most of the anterior and lateral walls of the larynx.

THE CRICOID CARTILAGE:

Ø  This lies below the thyroid cartilage and composed with hyaline cartilage.

Ø  It is signet ring shaped completely encircling the larynx with the narrow part anteriorly and the broad part posteriorly.

Ø  It also lined with ciliated columnar epithelium with muscles and ligaments attaches to its outer surface.

Ø  The lower border of the cricoids cartilage marks the end of the respiratory tract.

THE EPIGLOTTIS.

1.It is a LEAF shaped fibrocartilage attachéd to the inner surface of the anterior wall of the thyroid cartilage.

2. it is covered with strartified squamous epithelium.

3. if the larynx is likened to a box then the epiglottis is acts as the lid, it closes off the larynx during swallowing , protecting the lungs from accidental inhalation of foreign substances.

THE ADENOID CARTILAGES.

Ø  These are two roughly pyramid – shape hyaline cartilage.

Ø   It Suitated On Top Of The Broad Part Of The Cricoids Cartilage Forming Part Of The Posterior Wall Of The Larynx.

LIGAMENTS AND MEMBRANES

There are several ligaments that attaches the cartilages to each other end and to the hyoid bone.

6.BLOOD SUPPLY

ARTERIAL SUPPLY:Superior and inferior laryngeal arteries.

VENOUS DRAINAGE: The thyroid veins , which joins the internal jugular vein .

7. NERVE SUPPLY:

 PARASYMPATHETIC NERVE SUPPLY:

                     From the superior laryngeal nerves which are branches from the VAGUS nerve.

SYMPATHETIC NERVE SUPPLY:

From the superior cervical ganglia , one on each side.

8.INFERIOR OF THE LARYNX.

 The vocal cords are two pale folds of mucus membrane with cord-like free edges.

The space between the vocal cords is called GLOTTIS.

9.FUNCTIONS

1.   PRODUCTION OF SOUND

                    Sound has the properties of pitch,volume and resonance.

2. SPEECH:

  This occurs during expiration when the sounds produced by the vocal cords are manipulated by the tongue,cheeks and lips.

3. Protection of the lower respiratory tract.

1. While swallowing of the food the larynx moves upwards, occluding opening it from the pharynx and the hinged epigilttis closes over the larynx.

2.  This Ensures That Food Passes Into The Oesophagus And Not Into The Lower Respiratory Passages.

4.PASSAGE FOR AIR.

 This is between the pharynx and trachea.

5.Humidifying, filtering and warming.

   These processes continue as inspired air travels through the larynx.