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 acoelomates - animals without a body cavity, Explain the Acoelo...

Explain the Acoelomates - Animals without a Body Cavity? The simplest group of animals that has bilateral symmetry and a solid body (acoelomate) is the Platyhelminthes. Phy

Categories of benthic flowering plants, Categories of benthic flowering pla...

Categories of benthic flowering plants Zone of emergent plants Consisting of plants whose roots and stems remain submerged in water and whose upper leaves and ste

Show characteristics of food products, Q. Show characteristics of food prod...

Q. Show characteristics of food products? These sensory characteristics of food products. Food quality, as such, can be divided into three main categories i.e. i. Appeara

How does the cellular immune response take place, Q. How does the cellular ...

Q. How does the cellular immune response take place? The lymphocytes that participate in the cellular immune response are the T lymphocytes and T lymphocytes differentiate into

Magnesium - mineral elements, Magnesium -  It is available in most of t...

Magnesium -  It is available in most of the plants, especially vegetables. By its deficiency diarrhoea is caused. Its important functions are - (a)      Along with c

What is etiopathology, Q. What is Etiopathology? Who is likely to devel...

Q. What is Etiopathology? Who is likely to develop gout? What are the risk factors? Let us find out. Gout is caused when there is over production of uric acid in normal purine

Help, about how humans survive and reproduce currently. In your journal, wr...

about how humans survive and reproduce currently. In your journal, write down three adaptations that help humans have differential survivability, and three adaptations that help hu

Physiology of digestion, PHYSIOLOG Y OF DIGESTION Food - omnivorous. D...

PHYSIOLOG Y OF DIGESTION Food - omnivorous. Digestion - Intercellular. (i) Mechanical - by chewing, deglutinationm, churnning, peristalais. Under control of medulla oblonge

Explain procedure for performing the completed coliform test, Explain Proce...

Explain Procedure for Performing the Completed Coliform Test? Completed test is the last step in the Coliform test procedure which is described herewith. Conduct the exercise f

Define major sources of water - water intake, Define Major Sources of water...

Define Major Sources of water - Water Intake? The preformed water that we consume as water or as beverage. This will include both preformed water in fluids and in foods. The am

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