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

Which are the respiratory muscles in mammals, Q. Which are the respiratory ...

Q. Which are the respiratory muscles in mammals? In mammals the muscles that participate in the breathing process are the diaphragm and the intercostal muscles, in respiratory

State the the amount of the nutrient, State the the amount of the nutrient ...

State the the amount of the nutrient On increasing the amount of the nutrient the yield increases and the decrease from the maximum i.e., (A-y) becomes less. Subsequent additio

History of ecology, History of Ecology The roots of ecology lie in Natu...

History of Ecology The roots of ecology lie in Natural History, which is as old as human civilisation itself. As a matter of fact man indulged in ecology in a practical sort of

Evolution, Who is the founder of theory survival of the fittest ?

Who is the founder of theory survival of the fittest ?

What is the name of the sea anemones and larva of corals, Q. What is the na...

Q. What is the name of the sea anemones and larva of corals? What is the biological importance of that larval stage? Sexual reproduction in sea anemones and corals have a larva

List the advantages of iopa and opg, List the advantages of IOPA and OPG ...

List the advantages of IOPA and OPG a) Advantages of IOPA are as follows  It is a useful high yield modality for ruling out local bone or dental disease  It is of value

Bovine spongiform encephalopathy (bse), Normal 0 false fal...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

What are flagella and cilia, Q. What are flagella and cilia and how do thes...

Q. What are flagella and cilia and how do these structures acquire movement? What are some examples of flagellated and ciliated cells in humans? Flagella and Cilia are structur

What are plasmids, What are plasmids? What is the importance of plasmids fo...

What are plasmids? What is the importance of plasmids for the recombinant DNA technology? Plasmids are circular fragments of DNA that are accessories to the major bacterial DNA

How to determines the actual availability of nutrients, How to determines t...

How to determines the actual availability of nutrients The amount of a particular nutrient determined analytically does not necessarily represent what is available but is merel

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