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

What do you mean by chromosome number, Q. What do you mean by Chromosome Nu...

Q. What do you mean by Chromosome Number? We are generally aware that the number of chromosomes in each cell of all individuals of a single species is constant. ,It is also est

Which of structures is the nuclear membrane composed, Q. which of structure...

Q. which of structures is the nuclear membrane composed? Eukaryotic cells have nucleus delimited with two juxtaposed membranes that continue with the membrane of the endoplasmi

What is the bone matrix, Q. What is the bone matrix? What are its main comp...

Q. What is the bone matrix? What are its main components? Bone matrix is the content that fills the intercellular space of the osseous tissue the bone matrix is made of mineral

Carbohydrates, CARBOHYDR A TES Carbohydrate = hydrate of carbo...

CARBOHYDR A TES Carbohydrate = hydrate of carbon. Hydroxyl group present. Aldehyde group or keto group may present. Carbohydrates are polyhydroxy aldehydes

Economic and ecological importance of molluscs, Q. What are examples of the...

Q. What are examples of the economic and ecological importance of molluscs? Molluscs are important players in several food chains in ecosystems. Many marine molluscs are part o

Complications of diabetes, Q. Complications of Diabetes? Diabetes, as y...

Q. Complications of Diabetes? Diabetes, as you know, is a lifelong disease. We have said earlier also that it can be controlled but not cured. Control of diabetes by ensuring n

Explain regulatory enzymes, Explain Regulatory enzymes Regulatory enzy...

Explain Regulatory enzymes Regulatory enzymes:   Citrate  synthase,  isocitrate  dehydrogenase  and a-ketoglutarate dehydrogenase complex are the key  enzymes which  regulate

Respiratory care on admission of patient, Respiratory Care on Admission (Fi...

Respiratory Care on Admission (First two hours) Patient is incubated and ventilator-dependent.  Monitor blood gases hourly and take corrective action immediately.

Define intentional adulteration - types of adulteration, Define Intentional...

Define Intentional Adulteration - Types of Adulteration? In intentional adulteration, the substance is added, removed or substitute knowingly by the adulterator for the purpose

What is megalobastic anemia, Question 1) What is megalobastic anemia? Disc...

Question 1) What is megalobastic anemia? Discuss briefly its lab diagnosis. How would you differentiate megaloblastic anemia from other anemias? Question 2) What is hem

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