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

Nervous system and sense organs, Nervous System and Sense Organs The n...

Nervous System and Sense Organs The non-chordates also perform a variety of activities such as feeding, digestion, locomotion etc. For this aim, they have corresponding organs

How are the male gametophytes, How are the male gametophytes and the male g...

How are the male gametophytes and the male gametes formed in angiosperms? In the anthers of every stamen there are pollen sacs. Within the pollen sacs there are microspore moth

File & chemical removal of gutta percha-endodontics, File  & chemical remov...

File  & chemical removal of gutta percha: -    K-type file & chloroform is the best choice in small and curved canals. -    The pulp chamber floated with chloroform, then k-typ

Growth and development of plants, Growth and Development of Plants You...

Growth and Development of Plants You must have seen beautiful plants growing in pots in a garden. The plant grows while the pot does not. As a rule living things grow, but non

What is the carbon cycle, What is the carbon cycle? The carbon cycle sh...

What is the carbon cycle? The carbon cycle shows the circulation and recycling of the chemical element carbon in nature as a result of the action of living beings. Photosynt

Define calcium - the macronutrient, Define Calcium - The Macronutrient? ...

Define Calcium - The Macronutrient? Calcium is an important mineral found mainly in bone and teeth. It is widely distributed in food substances such as milk, cheese, egg yolk,

What are the main cellular functions of potassium, Q. What are the main cel...

Q. What are the main cellular functions of potassium? Moreover being important for the osmotic regulation and for the acid-base equilibrium (pH) potassium is fundamental for th

Causes of diabetic ketoacidosis, Q. Causes of Diabetic Ketoacidosis? Th...

Q. Causes of Diabetic Ketoacidosis? The causes of Diabetic Ketoacidosis (DKA) are the following: - Missing of insulin injection - Infection - Trauma (injury) - Myoc

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