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

Define proteins as structural elements and structural units, Define Protein...

Define Proteins as Structural Elements and Structural Units? The liver cell membrane analysis shows that this membrane contains 50-60% protein, 35% lipids and 5% carbohydrates.

Explain the characteristics of cancer, Explain the Characteristics of Cance...

Explain the Characteristics of Cancer? The important characteristics of cancer are excessive cellular multiplication, invasiveness and autonomy. The active process of invasion

Distinguish between the terms pesticide and insecticide, Distinguish among ...

Distinguish among the terms 'pesticide', 'insecticide' and 'herbicide.   A pesticide is a compound which destroys or controls any organism which is considered to be harmful

Procedures related to hygenic care, PROCEDURES RELATED TO HYGENIC CARE ...

PROCEDURES RELATED TO HYGENIC CARE Would you like to remain without a bath on any given day? Do you remain without a bath when you are sick.? No one normally, would like to m

What possible combinations of chromosomes will be present, A diploid cell c...

A diploid cell contains three pairs of homologous chromosomes designated C1 and C2, M1 and M2, and S1 and S2; no crossing over occurs. What possible combinations of chromosomes

Assuming that the two traits assort independent, In holly, serrated leaves ...

In holly, serrated leaves are dominant to smooth-edged leaves, and red berries are dominant to green berries. Two holly plants heterozygous for leaf edge shape and berry color are

Determine the applications of biotin, Applications of Biotin Biotin is...

Applications of Biotin Biotin is mainly used in the preparation of injection, and also in the manufacture of vitamin B complex and multi-vitamin preparations. It is used in

Explain the psychological management of eating disorders, Explain the Psych...

Explain the Psychological Management of eating disorders? All anorexia nervosa or bulimia nervosa patients are resistant to any kind of therapy and hospitalization may be a lif

How ignorance and poor socioeconomic cause pem, How Ignorance and Poor Soci...

How Ignorance and Poor Socioeconomic cause PEM? Status Improper childcare, either as a result of lack of knowledge or lack of time for mother, could also contribute to the onse

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