Larynx

In animals, a cartilaginous windpipe is present inside the body. This windpipe connects the larynx to the bronchi of the lungs. This whole system helps in the breathing and speaking process. Let us come to our main question, what is larynx? The larynx is an organ that is involved in the sound production and breathing process. It also protects the trachea from food aspiration. The other name for the larynx is soundbox. The size of the larynx in the adult male is 44mm in length and in females, the length of the larynx is 36 mm. In this article, we have covered the larynx in detail, all the important points about the larynx like larynx function, structure, role, and position have been covered in detail.

Position of Larynx

The larynx lies in the anterior midline of the neck. It extends from the root of the tongue to the trachea. The position in the adult male is from C3 to C6 vertebrae. In adult female and children larynx lies in the C1 to C4 vertebrae position. The diameter of the larynx is around 3mm in the children and around 12 mm in the adults.

Larynx Structure

The larynx structure is composed of nine cartilages. Three cartilages are present in the paired form and the rest of the three cartilages are present in the unpaired form. Let us discuss these cartilages:

Paired Cartilages: 

In the larynx structure, the total number of paired cartilage is 6, as they are present in pair (3 * 2 = 6). 

Arytenoid Cartilage- These are the cup-shaped cartilages

Corniculate Cartilage- These are horn-shaped cartilages.

Cuneiform Cartilage- These are wedge-shaped cartilages.

Unpaired Cartilages: 

In the larynx structure, the total number of unpaired cartilage are three.

Thyroid Cartilage- These type of cartilages are shield shape or v shape.

Cricoid Cartilage- These cartilages occur in a ring form.

Epiglottis Cartilage- This cartilage has a leaf-like structure.

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Let us discuss these human larynx cartilages in detail

Thyroid Cartilage 

These cartilages are v-shaped in cross-section. It consists of two laminae; right lamina and left lamina. These two laminas are quadrilateral in shape. The anterior border of both the lamina joins together and forms laryngeal prominence. This prominence is known as Adam's apple. This portion of the lamina, where these are not joined together is known as thyroid notch. This lamina joins at right angles in male and female, they join at 120 degrees. The posterior border of these lamina forms an elongation known as horn or cornua. These are of two types; superior cornua and inferior cornua. 

Cricoid Cartilage

The inferior horn of the thyroid cartilage articulates with the cricoid cartilage inferiorly to form a joint. Therefore, this joint is known as a cricothyroid joint. The inferior border of the thyroid cartilage is connected to the cricoid cartilage in the median plane with the help of conus elasticus. The line present between the superior tubercle and inferior tubercle is known as the oblique line. 

Three muscles are attached to the oblique line. These muscles are:

• Thyrohyoid muscle

• Sternothyroid muscle

• Thyropharyngeus muscle

The lower border and inferior cornua give insertion to the cricothyroid muscle. The posterior border which is connected to the superior cornua and inferior cornua gives insertion to the palatopharyngeus, salpingopharyngeus, and stylopharyngeus. In the inner position of the thyroid cartilage, three muscles and three ligaments are attached. 

The cricoid cartilage is the complete cartilage. It encircles the above present cartilage (thyroid cartilage). It is stronger and thicker than the thyroid cartilage. It articulates superiorly with the arytenoid cartilage. 

Role of Larynx Muscle in Human:

• It helps in providing tensor strength to the larynx.

• These muscles act as an adductor substance.

• Posterior cricoarytenoid muscle helps in preventing the collapse. Therefore, it acts as a safety muscle.

• These muscles help in opening the inlet.

• These muscles help in the closing of the inlet.

Larynx Function

Some of the larynx function are discussed below:

• The larynx protects the lower airways.

• The larynx in human helps in phonation.

• Larynx function in respiratory system is the fixation of the chest.

• The larynx helps in the cough reflex.

• During the expiration, the vocal cord gets abducted with the help of the larynx muscle.

Did You Know?

• The cricoid cartilage forms the foundation stone of the cartilages.

• Epiglottis is present in the upper part of the larynx in the anterior wall.