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

Explain high fibre diets, High fibre diets High fibre  diets: The pat...

High fibre diets High fibre  diets: The patients  are advised  to  eat  high  fibre cereals as whole grain flour and bread, whole grain bread cereals, whole wheat pasta and b

What was necessary to develop regulations, Why it was necessary to develop ...

Why it was necessary to develop regulations on the preparation and sale?

Define total body potassium (tbk), Define Total Body Potassium (TBK)? ...

Define Total Body Potassium (TBK)? Potassium in the body is an index of body's total cell mass. A gamma counter measures the amount of a type of potassium which is assumed t

What do you mean by inflammation, Q. What is inflammation? Inflammation...

Q. What is inflammation? Inflammation is the initial response of the unspecific defense system versus aggressions against the body the aggressions may be caused by trauma, infe

Explain ground system, G round system:  Plant tissue system, composed com...

G round system:  Plant tissue system, composed commonly of parenchyma cells with some collenchyma and sclerenchyma cells, that occupies the space between the epidermis and the va

Explain covalent structure of rna, Like  DNA RNA  is  a  long  polymer  hav...

Like  DNA RNA  is  a  long  polymer  having  of  nucleotides joined by 3'5' phosphodiester  bonds. Furthermore, there are some differences: ?   The bases in RNA are adenine abbr

Phlum arthropoda, how to write a project on phylum arthropoda

how to write a project on phylum arthropoda

What are the two groups of defense mechanisms of the body, What are the two...

What are the two groups of defense mechanisms of the body against foreign or harmful agents? What is the difference between them? The body has many defense mechanisms against f

What are respiratory pigments, What are respiratory pigments? What is the r...

What are respiratory pigments? What is the respiratory pigment present in some arthropods? Which is the analogous molecule in humans? Respiratory pigments are molecules able t

How to antioxidants work in cancer prevention, How to antioxidants work in ...

How to antioxidants work in Cancer Prevention? As cells function normally in the body, they produce damaged molecules called free radicals. These force radicals, we learnt are

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