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

What is the concept of universality of the genetic code, What is the concep...

What is the concept of universality of the genetic code? What are the exceptions to this universality? The genetic code is universal because the rules of protein codification b

Explain the phase contrast microscope, Explain the Phase Contrast Microscop...

Explain the Phase Contrast Microscop? Unpigmented and unstained living cells can be easily observed by phase contrast microscope. It has a special objective and a condenser th

Explain about the vacuum evaporators, Explain about the Vacuum Evaporators?...

Explain about the Vacuum Evaporators? It is common to construct various vacuumised vessels in series that is why the product moves from one vacuum chamber to the next and thus

Dormancy - plant growth substances, Dormancy - Plant Growth Substances ...

Dormancy - Plant Growth Substances Dormancy can be defined as a state of suspended growth and metabolism. When most plants are exposed to seasonal periods of very inclement we

Head stream of highland brook zone, Head stream of Highland brook zone ...

Head stream of Highland brook zone This is formed by a number of small streams, which originate from a marsh, a spring or a glacier. This is a small shallow zone with an irreg

Define determinants of food security - public nutrition, Define Determinant...

Define Determinants of Food Security - Public Nutrition? We learnt above that there is also a qualitative aspect to food security, which compels the perception of food not only

Explain the nutritional and functional role of zinc, Minerals  :-  Zinc ...

Minerals  :-  Zinc Food Source      Meats, cereals.  Nutritional Functional role Essential nutrient: Deficiency produces loss of appetite, growth retardation, skin

Systemic emboli, Osler's nodes are small, tender subcutaneous nodules that ...

Osler's nodes are small, tender subcutaneous nodules that develop in the pulp of the digits or occasionally more proximally in the fingers and persist for hours to several days. Th

Virus, #question.bacteria and virus are meet so what happen.

#question.bacteria and virus are meet so what happen.

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