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

Difference between fat-soluble and water-soluble vitamins, Q. What is the d...

Q. What is the difference between fat-soluble and water-soluble vitamins? Why can fat-soluble vitamins cause harm when ingested in excess? Water-soluble vitamins are those vita

Endomitosis, why and where endomitosis happen.........?

why and where endomitosis happen.........?

What are pentoses, What are pentoses? What are the roles of pentoses in DNA...

What are pentoses? What are the roles of pentoses in DNA and RNA molecules? Pentoses are carbohydrates made of five carbons. The DNA molecule is made of a sequence of molecu

Enumerate in detail about the cytoskeleton, Enumerate in detail about the C...

Enumerate in detail about the Cytoskeleton All eukaryotic cells have distinct shapes, and are also capable of assuming different shapes. 'The internal organelles of a cell are

Determine the use of opg, Determine the use of  OPG An OPG is used to...

Determine the use of  OPG An OPG is used to see the possibility for an anterior loop which is found to extend about 1-3 mm anterior to the mental foramen in about 12 per cent

What do adp and atp mean, Q. What do ADP and ATP mean? What are the functio...

Q. What do ADP and ATP mean? What are the functions of these molecules for the cellular energetic metabolism? ADP is an short form of adenosine diphosphate, two molecules of ph

What is pulmonary stenosis, Pulmonary Stenosis :  The obstruction may be v...

Pulmonary Stenosis :  The obstruction may be valvar, infundibular or supra valvar.

Describe the structure of lipoprotein, There are several different lipoprot...

There are several different lipoprotein species found in plasma but their basic structures are similar. The insoluble lipid (cholesterol ester and triglyceride) forms a central cor

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