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 the appropriate controls and the possible results, After the virus c...

After the virus capsid containing vimentin gets into the nucleus it is broken down and the DNA is released. Whether capsid proteins are broken down into amino acids or remain intac

Tools used in taxonomy, Q. Tools used in Taxonomy? Before you plan for ...

Q. Tools used in Taxonomy? Before you plan for a field trip decide the tools and equipment required. Certain, equipments are necessary for plant collection. A collecting pick i

Cellular type - endosperm, Cellular Type - Endosperm In this type, as...

Cellular Type - Endosperm In this type, as the name indicates, the division of the primary endosperm nucleus is immediately followed by the laying down of a wall, which is us

Paratyphoid and other salmonella infections, P a r a typhoid and other ...

P a r a typhoid and other Salmonella infections Paratyphoid salmonellae are non-host-specific. The commonly reported species are S. Typhimurium, S . Enteritidis S . T

Define polyacrylamide gel electrophoresis (page), Define Polyacrylamide gel...

Define Polyacrylamide gel electrophoresis (PAGE)? Acrylamide gel has the advantage over starch in that it is easier to prepare and is more inert, the pore size can be varied in

Circulatory fluid in the body of cockroach, Can all the four chambers of th...

Can all the four chambers of the human heart experience systole simultaneously? Describe justifying your answer. What do you call the circulatory fluid in the body of cockroach

Theories to explain fine structure of chromosome, THEORIES TO EXPLAIN FINE ...

THEORIES TO EXPLAIN FINE STRUCTURE OF CHROMOSOME (1 ) Multistranded theory Steffenson 1959 - each chromosome composed of two chromatids (Half Chromosome) and each chromat

Define poverty and ignorance - cause of anaemia is dietary, Define Poverty ...

Define Poverty and ignorance - cause of anaemia is dietary? Low purchasing power of the communities and their consequent inability to meet the nutrient requirements, even after

Agro industrial-complication during gestation, Complication during gestatio...

Complication during gestation Many complications like uterine torsion, vaginal prolapse, mummification, foetal maceration, hydra allantois, hydro amnios and teratological abno

Craninal nerves, Craninal nerves: Cranial nerves take their origin f...

Craninal nerves: Cranial nerves take their origin from different areas of brain  Some of them are sensory, some are motor and a few are mixed nerves. There are 12 pair

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