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

Different osmotic pressures, Q. Can solutions with the same concentration o...

Q. Can solutions with the same concentration of diverse solutes have different osmotic pressures? The osmotic pressure of a solution does not depend on the nature of the solute

Rules followed by diabetic patient, Q Show Rules followed by diabetic patie...

Q Show Rules followed by diabetic patients? A  "sick day" is any health problem diabetic patient may have. This could include a common cold, infection, diarrhoea, fever, injury

Name the organism included in symbiotic nitrogen fixation, Name the organis...

Name the organism included in symbiotic nitrogen fixation. What are the components needed for this pure? Determine their role. Differentiate among inbreeding and heterosis. The

Can you explaon about aortography, Q. Can you explaon about Aortography? ...

Q. Can you explaon about Aortography? Visualization of the aorta and its branches is possible by several modalities today. Apart from angiography, aorta can also be visualized

Heteromorphic types - intra specific incompatibility, Heteromorphic Types -...

Heteromorphic Types - Intra specific Incompatibility Plants of the same species produce flowers that differ in morphology. This involves two (distyly) or three (tristyly) morp

Determine net atp production after complete oxidation, How do you determine...

How do you determine net atp production after complete oxidation to CO2 and H2O using mitochondrial?-oxidation, the TCA cycle, the mitochondrial electron transport chain and oxidat

Evaluation of specific radiographs, Evaluation of Specific Radiographs ...

Evaluation of Specific Radiographs Intra oral peri apical radiographs, cephalograms, panoramic radiographs and Computed tomographies are necessary for complete survey of teeth

The immediate effects of exercise on the heart and the lungs, (a) What are ...

(a) What are the immediate effects of exercise on the functions of (i) the heart, (ii) the lungs, (iii) the liver? (b) How do these changes help to meet the needs of exercise

Genetics what is this type of gene frequency change called, An hypothesis f...

An hypothesis for the extinction of the dinosaurs is that the earth had been hit by a gigantic meteor that caused the death of those big reptiles. In that case the entire genetic p

Byproducts of low digestibility and low nitrogen, Byproducts of low digesti...

Byproducts of low digestibility and low nitrogen Straws, husks, pods and haulms are the byproducts of this category. Very often the nitrogen content in these byproducts is so l

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