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 nutritional assessment methods, Define the Nutritional assessmen...

Define the Nutritional assessment methods? Nutritional assessment methods commonly used are enumerated herewith. 1. Bodyweight measurement s remain to be the most practical

Define recommended dietary allowance for vitamin a, Requirement and Recomme...

Requirement and Recommended Dietary Allowance (RDA) for Vitamin A? Recommendations for adequate vitamin A intake based on the amounts needed to correct night blindness among vi

Inhalation route for injection, Inhalation Route for Injection Therapi...

Inhalation Route for Injection Therapies that can be administered by inhalation are oxygen, humidification-cool mist and steam, administering local medication. The commonly u

What is the cell division process, What is the cell division process direct...

What is the cell division process directly related to the embryonic growth? The embryonic growth depends directly on mitosis. By this type of cell division the zygote separates

Explain some effect of inadequate nutrition, Explain some Effect of Inadequ...

Explain some Effect of Inadequate nutrition? Inadequate nutrition ranks as one of the major problems of old age. Various factors which may be responsible for the change in one

Difference between translation and transcription, Q. What is the difference...

Q. What is the difference between translation and transcription? Transcription is the name given to the formation of DNA molecules from an open DNA chain used as a template, Tr

Explain fontan operation and ross operation in heart dieases, Explain fonta...

Explain fontan operation and ross operation in heart dieases? Fontan Operation: The Fontan principle involves redirecting the whole systemic return into the lungs bypassing t

Amino acid, Amino acid is any of a class of 20 molecules which are combine...

Amino acid is any of a class of 20 molecules which are combined to form the proteins in living things. Consisting of the general formula NH2-CHR-COOH, where "R" is the side chain

Significance of mitosis, Significance of Mitosis 1.      Reproduction ...

Significance of Mitosis 1.      Reproduction ;   William Bateson 1906 wrote, Whenever  I observe a dividing  cell under  the  microscope , I feel  as if the original act of  c

What is the use of uncoated polyvinyl chloride, Q. What is the use of Uncoa...

Q. What is the use of Uncoated polyvinyl chloride? Uncoated polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC): PVC and PVDC are closely related plastics that are a

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