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 functions of fluoride, Define Functions of fluoride? The only b...

Define Functions of fluoride? The only beneficial role demonstrated for fluoride is in reducing the prevalence and severity of dental caries in children and adults. This is en

Define the dietary and lifestyle modifications - obesity, Define the Dietar...

Define the Dietary and Lifestyle Modifications - Obesity? The management of obesity basically comprises the following three- pronged approach. a) Dietary modifications b)

What are the parathyroids, What are the parathyroids? Where are they locate...

What are the parathyroids? Where are they located and what are the hormones secreted by these glands? The parathyroids are four small glands embedded two in every posterior fac

Summary of economic dimensions of financing healthcare, Normal 0 ...

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

Explain about the glycoproteins, Explain about the Glycoproteins? Most...

Explain about the Glycoproteins? Most of the naturally occurring conjugated proteins are glycoproteins. Sugar molecules are covalently bound to them, especially those secreted

Diminished oxygen-carrying capacity of hemoglobin, Manifestations of anemia...

Manifestations of anemia that are directly due to the diminished oxygen-carrying capacity of hemoglobin include: Answer A. pale skin. B. bleeding. C. bone pain. D. fatigue.

Amphibians, Amphibians is the class of terrestrial vertebrates which lay t...

Amphibians is the class of terrestrial vertebrates which lay their eggs (and mate) in water but live on land as adults following the juvenile stage where they live in water and br

Integral membrane protein movement and distribution, Various proteins are f...

Various proteins are free to take a move laterally in the plane of the bilayer. One experiment used to represent this included fusing cultured mouse cells with human cells under ap

What are typical fauna of the tropical forests, What are the typical vegeta...

What are the typical vegetation and the typical fauna of the tropical forests? In the vegetation of a tropical forest broadleaf evergreen trees predominate. On the top of the t

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