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

About ribosome, Which type Ribosome occurs exclusivley in Mitocondria?

Which type Ribosome occurs exclusivley in Mitocondria?

Protozoans, classification on protozoans

classification on protozoans

What is brown algae, What is Brown Algae ? Phaeophyta are commonly know...

What is Brown Algae ? Phaeophyta are commonly known as brown algae; precisely because they are - guess what? - brown in color! They are brown because they contain brown colored

Define the clinical manifestations of underweight, Define the Clinical Mani...

Define the Clinical Manifestations of Underweight? Underweight may predispose to fatigue, lethargy and breathlessness. Iron-deficiency anaemia is usually seen because the diet

Llustrate the role of each area in the evolution of the hebe, llustrate the...

llustrate the role of each area in the evolution of the Hebe Uses appropriate examples from the Hebe data to illustrate the role of each area/concept in the evolution of the He

Ovule, Ovule The ovule, also known as the megasporangium is the forer...

Ovule The ovule, also known as the megasporangium is the forerunner of the seed. It consists of a central mound of tissue called the nucellus, which is enveloped by one or tw

Define the word glycemic, Glycemic or sugar control The control of bloo...

Glycemic or sugar control The control of blood sugar is one of the most important factors of good care for the diabetic patient. It has been shown that good glycemic or sugar c

Explain the chemotherapeautic rinses, Explain the Chemotherapeautic rinses ...

Explain the Chemotherapeautic rinses Chemotherapeautic rinses:  The use of  0.12  per cent chlorhexidine has been proven to be of therapeutic significance in maintaining period

Define chronic fever and infection, Chronic fever and  infection Chron...

Chronic fever and  infection Chronic fever  and  infection are always supported will a long standing history of symptoms  or repeated episodes of infection. One of the commonl

Name the organism included in symbiotic nitrogen fixation, Name the organis...

Name the organism included in symbiotic nitrogen fixation. What are the components needed for this pure? Determine their role. Differentiate among inbreeding and heterosis. The

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