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

Sterility in angiosperms, Sterility in Angiosperms Sterility in angios...

Sterility in Angiosperms Sterility in angiosperms may arise due to several causes. Either the anther may not be formed, or anthers are formed but meiosis may be abnormal. A

Respiration in cockroach, what is the chemical reaction of respiration in c...

what is the chemical reaction of respiration in cockroach?

What is glucose tolerance test, Q. What is Glucose Tolerance Test? Gluc...

Q. What is Glucose Tolerance Test? Glucose Tolerance Test (GTT) is used for diagnosis of diabetes mellitus. In this test, blood sugar levels are measured after giving glucose

Vertebrates - osmotic and ionic regulation, Normal 0 false fa...

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

Explain about cerebral hemispheres, How is it structurally explained that t...

How is it structurally explained that the motor activity of the left side of the body is controlled by the right cerebral hemisphere and the motor activity of the right side of the

Factors influencing rs content -amylose or amylopectiz ratio, Explain the F...

Explain the Factors Influencing RS Content -Amylose or Amylopectiz ratio? Amylose/Amylopectirz ratio: In general, foods containing high amylose/amylopectin ratio lead to higher

Explain adverse effects of lactic acidosis, Adverse effects of Lactic acido...

Adverse effects of Lactic acidosis- Lactic acidosis and severe hepatomegaly with steatosis have been reported with use of other nucleoside analogs. The most common adverse effe

Contrast the reproduction of bacteria with that of frogs, Contrast the repr...

Contrast the reproduction of bacteria with that of frogs. Bacteria replicate asexually by splitting in two. Frogs reproduce sexually by producing sperm and eggs. One sperm and

Fixism what are the main arguments that favor evolutionism, In the scientif...

In the scientific competition against fixism what are the main arguments that favor evolutionism? The major arguments in favor of evolutionism are paleontological, from the stu

Natural and artificial ecosystem, Natural and Artificial Ecosystem i) N...

Natural and Artificial Ecosystem i) Natural ecosystems are those which are mostly free from human disturbances, such as tropical forests, grasslands, oceans, lakes and deserts.

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