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

Amphibians, respiratory system in amphibains

respiratory system in amphibains

Explain about human auditory sensitivity, What are the structures that part...

What are the structures that participate in the human auditory sensitivity? The structures of the human auditory sensitivity are the ears (external, middle and internal), the

First stage of invagination, First Stage of Invagination The large en...

First Stage of Invagination The large endodermal cells that are remaining in the vegetal plate move laterally towards the centre of the plate and fill the gap in the vegetal

What is the vector of malaria, What is the vector of malaria? How different...

What is the vector of malaria? How different is its behavior from the behavior of the vector of dengue fever? The vector of malaria is a mosquito of the genus Anopheles, also k

What is the action mechanism of the antiretroviral drugs, What is the actio...

What is the action mechanism of the antiretroviral drugs called protease inhibitors which are used against HIV infection? Protease inhibitors are some of the antiretroviral dru

What is the photoperiod, What is the photoperiod? The Photoperiod is th...

What is the photoperiod? The Photoperiod is the daily time period of light exposure of a living being and the photoperiod may differ according to the period of the year.

Inrinsic conduction system of the heart, The cardiovascular system controls...

The cardiovascular system controls the movement of blood through thousands of miles of capillaries so that every tissue  in every part of the body is perfused. Essential nutrients

Name element playing significant role in nitrogen fixation, An element play...

An element playing significant role in nitrogen fixation is : 1.  Molybdenum 2. Copper 3. Manganese 4. Zinc An element playing significant role in nitrogen fixation

The statement is true or false, True or false, adaptations are the result o...

True or false, adaptations are the result of finding the best or only solution to a given problem a species faces.

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