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

Define regulation and excretion of sodium and chloride, Define Regulation a...

Define Regulation and Excretion of sodium and chloride? Renal excretion and retention of these elements is closely regulated. The total content of body sodium especially the co

Problem of potency of blastema cells, Problem of Potency of Blastema Cells ...

Problem of Potency of Blastema Cells The local cells are accountable for regeneration. Now you could ask which of the blastema cells differentiated into which type of limb ti

Properties of foods, Q. Properties of foods? various properties of food...

Q. Properties of foods? various properties of foods, under which the quality attributes of foods were introduced to you in terms of food quality and its categories as appearanc

Deficiency diseases-evaluation of production diseases, Evaluation of produc...

Evaluation of production diseases Generally, production diseases are acute states and respond dramatically to administration of a deficient nutrient or metabolite. The nutriti

Define advantages of using the plate counts method, Define Advantages of Us...

Define Advantages of Using the Plate Counts Method? 1. It is simple and sensitive method. 2. It provides viable count as only live cells will grow and produce the colony.

Explain counseling children, Counseling children Assess the child's sta...

Counseling children Assess the child's stage of development. Adjust counseling for a child's  dependency needs,  lack of  experience and  the development tasks faced by  him

Tracheoles - respiration, Tracheoles - Respiration The tracheal syste...

Tracheoles - Respiration The tracheal system consists of an air filled system of tubes - the tracheal tubes that branch repeatedly until they become fine as capillaries, and

Muscular tissue, MUSCULA R TISSUE Muscular tissue in general develop...

MUSCULA R TISSUE Muscular tissue in general develops from the mesoderm of the embryo but the muscles of the iris of the eye and myoepithelial cells of the salivary, mammar

What is the possible dna sequence, Insulin was the first protein to be sequ...

Insulin was the first protein to be sequenced biochemically. Assuming that there were no introns involved in the process, what are the possible DNA sequences that produced the last

Show the principle parts of a mold, Q. Show the principle parts of a mold? ...

Q. Show the principle parts of a mold? The principle parts of a mold are a web-like structure known as mycelium and the spore. The mycelium is often white and cottony and penet

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