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 original concentration, A sample of yeast cells was serially di...

A sample of yeast cells was serially diluted 1/10 five times then serially diluted 1/3. the number of yeasts was338 yeasts per ml. what was the original concentration? Please show

Designer meat products, D e s ign e r Meat Products Designer/healt...

D e s ign e r Meat Products Designer/health meat products low in sodium, fat, calories could be produced by incorporating fat replacers, fibers and natural antioxidants an

The immediate effects of exercise on the heart and the lungs, (a) What are ...

(a) What are the immediate effects of exercise on the functions of (i) the heart, (ii) the lungs, (iii) the liver? (b) How do these changes help to meet the needs of exercise

Define aerobic respiration, Where in mitochondria does the process called r...

Where in mitochondria does the process called respiratory chain happen? Which are the products of the Krebs cycle used in that final phase of the aerobic respiration? Respirat

Scientific methord, how adoctor dicide a sickness of a patiant

how adoctor dicide a sickness of a patiant

Dictyosomes, Dictyosomes  are produced on the Organelles in the plant cells...

Dictyosomes  are produced on the Organelles in the plant cells composed of the series of flattened membrane sacs which sort, chemically modify, and package protein srough endoplasm

How different are pteridophytes from bryophytes, How different are pteridop...

How different are pteridophytes from bryophytes regarding substance transport? Pteridophytes are tracheophyte (vascular) plants, i.e., they have tissues specialized in conduct

Explain the uses of isp in seafood products, Explain the Uses of ISO in Sea...

Explain the Uses of ISO in Seafood products  Seafood products  The most significant application in this category is the use of ISP in fish sausage and surimi based restructu

Determine the nutritional and functional role of selenium, Minerals:- Sele...

Minerals:- Selenium  Food Source       Sea food, organ meats, cereals (levels vary depending on soil levels) Nutritional Functional role Essential nutrient: Keshan

Explain adefovir dipivoxil, Adefovir dipivoxil (Hepsera)  This phosphon...

Adefovir dipivoxil (Hepsera)  This phosphonate nucleoside analog, administered as the oral prodrug, inhibits replication of HBV, including variants resistant to lamivudine. Ade

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