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

Digestion, In humans, starch digestion begins in the buccal cavity, but sto...

In humans, starch digestion begins in the buccal cavity, but stops in the stomach .Why?

Medtronic hancock-biological valves, Medtronic Hancock (Standard Model) :  ...

Medtronic Hancock (Standard Model) :  These are gluteraldehyde preserved xenograft aortic valve, which are mounted. The modified orifice version (M-0) is one where the right

Discuss the role of nadph in erythrocytes, Discuss the role of NADPH in ery...

Discuss the role of NADPH in erythrocytes The fragility of erythrocytes  is impaired in the absence of NADPH generation due to the deficiency of glucose-6-phosphate dehydrogena

Other complications of prosthetic valves, Other Complications of Prosthetic...

Other Complications of Prosthetic Valves :  One of the dreaded complications of mitral valve replacement is ventricular rupture. It is difficult to manage and so it is better avoi

Concept of fitness, While discussing the Darwinian premise of natural selec...

While discussing the Darwinian premise of natural selection we observed that the term selection is synonymous with non-random reproduction, and that the success of the survivors is

Define assessment of selenium status, Define Assessment of Selenium Status?...

Define Assessment of Selenium Status? Blood glutathione (GSH) peroxidase activity is directly related to blood selenium up to a level of 1.27 μmoles/L. Beyond this point, the a

Carbohydrates requirement in chronic diarrhoea, Q. Carbohydrates requiremen...

Q. Carbohydrates requirement in chronic diarrhoea? Adequate amount of carbohydrates i. e 60-65% of the total energy should be given to the patient. Easily assimilated carbohydr

How did darwin reach the principle of natural selection, How did Darwin rea...

How did Darwin reach the principle of natural selection from the observation of differences among individuals of the same species? The Darwin recognized that in a same species

Determine the functions of human body system, Determine the function of hum...

Determine the function of human body system Human body has different systems to perform different functions. A system consists of organs to perform a particular set of function

Is it possible x chromosome of women come from father, Is it possible that ...

Is it possible that an X chromosome of a woman can have come from her father? It isn't only possible that an X chromosome of a woman is from her father, it is certain. Each wom

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