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

Categorisation of major brain functions, Categorisation of Major Brain Func...

Categorisation of Major Brain Functions As a framework, the major brain functions typically divided into modalities and domains. The major modalities are motor function and th

Fossilisation, FOSSILIS A TIO N - The organisms are preserved and...

FOSSILIS A TIO N - The organisms are preserved and fossilized when they are buried in the ice, in an oil rich soil, in the lava of volcano, in swamps, in desiccated deser

Define the word solute, Define the word solute A solution is a homogeno...

Define the word solute A solution is a homogenous mixture of two or more different substances. For instance salt in water form a solution. This means that the dissolved subs

Query, How can I get assignment order

How can I get assignment order

Natality rate - natality, Natality Rate - Natality Natality rate or bi...

Natality Rate - Natality Natality rate or birth rate is determined by dividing the number of individuals born by unit time and is expressed as follows: Natality rate =  ΔNn

Invertebrate, classification of invertebrate

classification of invertebrate

Define the process of feeding 0-6 months infant, Define the Process of Feed...

Define the Process of Feeding 0-6 Months Infant? The term exclusive breast feeding is used when all fluids, energy and nutrients are provided by breast milk, with the possible

What are the symptom of short bowel syndrome, Q. What are the Symptom of sh...

Q. What are the Symptom of short bowel syndrome? Diarrhoea is the main symptom of short bowel syndrome. Other symptoms include: • Anorexia • Steatorrhoea • Heart bum a

What are the stages into which photosynthesis is divided, What are the stag...

What are the stages into which photosynthesis is divided? Photosynthesis is separated into the photochemical stage, or light reactions, and the chemical stage. Photosynthesi

Define growth and development of infants and preschoolers, Define Growth an...

Define Growth and Development of Infants and Preschoolers? In this unit, we learnt about the various aspects related to the growth and development of infants and preschoolers.

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