Pharynx and larynx, Biology

Assignment Help:

Pharynx:

Pharynx  is a funnel shaped tube about  13cm long that  starts at the internal nares and  extends to the  level of the cricoid cartilage. It  lies posterior  to the nasal  and oral cavities, superior to  larynx and just anterior to the cervical vertebrae.  Its walls are composed of skeletal muscles and  lined by mucous membrane. Three parts of pharynx are nasopharynx, oropharynx and  laryngopharynx. The nasopharynx  is posterior  to nasal cavity. The two  internal nares,  to  eustachian tubes and  the oropharynx are the openings of nasopharynx. Oropharynx  lies posterior  to oral cavity, extends from the  soft palate inferiorly to  the  level of hyoid bone, lined with non-keratinized stratified squamous epithelium. Two pairs of  tonsil are found  in oropharynx. Laryngopharyx begins at  the  layer of hyoid bone,  lined by  non-keratinized stratified squamous epithelium, opens into oesophagus posteriorly and the larynx anteriorly. Pharynx  serves as a passage way  for air,  food and drink, and provides resonating chamber for speech sounds. 

Larynx:

Larynx or voice box  is a short passage way that connects the  laryngopharynx with trachea. It lies in the midline of the neck anterior to oesophagus and corresponds with the levels of cervical 4 to 6 vertebrae. Its wall is  composed of nine pieces of cartilage-3 single-thyroid, epiglottis and cricoid and 3  in pairs- arytenoid, cuneiform and  comiculate cartilages. Arytenoid  influencerhe positions and tensions of vocal  folds. Thyroid cartilage, two  fused plates of hyaline cartilage to  form the  anterior wall of the  larynx giving a triangular shape. Epiglottis  is  large, leaf shaped having a stem which  is attached to  the anterior rim of  the  thyroid cartilage and hyoid bone and  a broad superior  'leaf' portion unattached and  free to move up and down. During swallowing epiglottis moves down and  forms a  lid over glottis closing the entrance to larynx to prevent the entry of food or drink. When small particles of food, drink or dust enter the larynx a cough reflex occurs to expel the material. 

Arytenoid cartilages are two  small structures situated on the upper surface of  the expanded signet portion of the cricoids cartilage. They give attachment  to the posterior  ends of the true vocal  cords. The true vocal cords are fibro elastic bands extending from the posterior aspects of the thyroid cartilage in front to the arytenoids cartilage behind. The false vocal cords are two loose folds of mucous membrane situated above the  true cords. Larynx is lined by mucous membrane which, except over the vocal cords,  is covered with ciliated columnar epithelium.  


Related Discussions:- Pharynx and larynx

Chromsome, How does a person with drown syndrome obtain a third chromosome ...

How does a person with drown syndrome obtain a third chromosome 21?

Explain heterozygous individual and homozygous individual, What is the ge...

What is the genetic condition in which the heterozygous individual has different phenotype from the homozygous individual? This situation is called lack of dominance and it can

Explain fusion inhibitor, Fusion inhibitor  After HIV binds to the host...

Fusion inhibitor  After HIV binds to the host cell surface, a conformational change occurs in the transmembrane glycoprotein sub- unit (gp41) of the viral envelope, facilitatin

Why to dilute this stock to give the desired concentration, You are working...

You are working on a protocol in lab that requires 10ml of a 5% saline solution for a particular step. All you have in your lab is a 20% saline stock solution. How can you dilute t

What is the activation center of an enzyme, What is the activation center o...

What is the activation center of an enzyme? Is it the key or the lock of the lock and key model? The activation center is a region of the enzyme formed by its spatial conformat

Define starch gelatinisation, Starch Gelatinisation Starch is insolubl...

Starch Gelatinisation Starch is insoluble in cold water but in warm water it swells until its gelatinization temperature begins to lose its structure and leaches out its  8con

What do you understand by cyanogenic glycosides, Q. What do you understand ...

Q. What do you understand by Cyanogenic glycosides? Cyanogenic glycosides are present in a number of food plants and seeds. Cassava is a staple dietary item in tropical Afri

Gene constructs - transgenic animals, G e n e constructs Designing a...

G e n e constructs Designing and cloning of the gene construct is the fundamental step in the generation of transgenic animals, essentially determining success or failure of

What are muscle tissues, What are muscle tissues? How is the function of th...

What are muscle tissues? How is the function of this tissue related to the typical characteristics of its cells? Muscle tissues are tissues made of cells able to perform contr

Show complications of mitral stenosis, Q. Show Complications of Mitral Sten...

Q. Show Complications of Mitral Stenosis ? Hemoptysis It is a common complication in patients with mitral stenosis and is related to the severity of mitral stenosis. Pulm

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd