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

Explain the terms - sulphur and boron, Sulphur and Boron Boron is extra...

Sulphur and Boron Boron is extracted with hot water. Sulphur is extracted with 500 ppm solution of P solution (prepared from potassium dihydrogen orthophosphate or monocalcium

Zoology, main external morphological feature that differentiates platyhelmi...

main external morphological feature that differentiates platyhelminthes from nematodes

Pasteur''s experiment, Louis Pasteur (1860-1862) French): Even after th...

Louis Pasteur (1860-1862) French): Even after the experiments of Spallanzani, the conflict of a biogenesis and biogenesis continued well into the middle of 19 th century till

Molecular biology and technology, what are protein? What is the constituent...

what are protein? What is the constituential uni. Of protein? Briefly explain the various forms of protein?

After the morula stage what is the next stage, Q. After the morula stage wh...

Q. After the morula stage what is the next stage? What is the morphological feature that defines this stage? In the blastula stage the compactness is lost and an internal cavit

Atrial fibrillation or flutter, Q. Atrial Fibrillation or Flutter? Tran...

Q. Atrial Fibrillation or Flutter? Transient atrial fibrillation or flutter is seen frequently and can be associated with CAD, rheumatic heart disease, thyrotoxicosis, or myoc

How are grasslands classified, How are grasslands classified? Grasslan...

How are grasslands classified? Grasslands might be classified into steppes and savannahs. In the steppes the prevailing vegetation is grass, as in the pampas of South America

Define the techniques of instrument retrieval, Define the Techniques of Ins...

Define the Techniques of Instrument Retrieval Endo Extractor (Brasseler) a. Hollow tube bonded to coronal tip of separated instrument by cyanoacrylate adhesive, with

Illustrate sulfur photosynthetic bacteria, Q. What is the molecule that don...

Q. What is the molecule that donates hydrogen for photosynthesis, in sulfur photosynthetic bacteria? In sulfur photosynthetic bacteria the substance that donates hydrogen is hy

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