Pharynx and larynx, Biology

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.  

Posted Date: 10/27/2012 7:41:01 AM | Location : United States







Related Discussions:- Pharynx and larynx, Assignment Help, Ask Question on Pharynx and larynx, Get Answer, Expert's Help, Pharynx and larynx Discussions

Write discussion on Pharynx and larynx
Your posts are moderated
Related Questions
Sex Determination - Reproduction Sex, whether an individual will be a male or a female is determined at fertilisation, and this directs and controls all the later processes i

Similarities in body parts often indicate shared ancestry. Which of the following is true? Structures used for different purposes in different groups can be controlled by the same

How could knowledge of a pest organism's tolerance limits be used in pest control? Pesticides could be developed that make those limits narrower, environmental conditions could


The Period of Persecution: Earlier. treatment of  the  inentally sick depended on men's various superstitious beliefs.  It was thought that sounds and motions are  the factors

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

Explain prevention of endocarditis Many physicians believe that antimicrobial prophylaxis before process that may cause transient bacteremia can stop endocarditis and prostheti

Briefly explain Lichens organism? Lichens are unique organisms consisting of a symbiotic relationship between a fungus and a photosynthetic organism. They represent a type of s

Q. From which germ layer do blood cells originate? What are other organs and tissues made from that germ layer? Blood cells have a mesodermal embryonic origin and other organs

why does the removal of extremity of coleoptile prohibit plant growth?