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

External morphology of human heart, EXTERNA L MORPHOLOGY - Auricle ...

EXTERNA L MORPHOLOGY - Auricle 2 in number at broad area. Both are small, flap like cover ventricles like caps i.e. auricular appendix . It's skeleton is made up of mus

How many different gene types are possible, In lab rats, hair color and tex...

In lab rats, hair color and texture are controlled by two genes, the A gene for color and the B gene for texture. in both of these genes, the alleles show no dominance to each othe

Apex locator in retreatment cases-endodontics principles, Apex locator in r...

Apex locator in retreatment cases: -    Electronic apex locators may give misread for working length when gutta-percha is initially being removed. -    Due to that file beging

Disorder of platelets - purpura, Disorder of Platelets - Purpura Purpu...

Disorder of Platelets - Purpura Purpuras  are bleeding disorders characterised by petechiae  and ecchymosis which may be due to deficiency in either,  the number or quality of

Supenisory nursing round, Supenisory Nursing Round: Supervisory rounds...

Supenisory Nursing Round: Supervisory rounds are tours or excursions into areas where patients are cared for where personnel operate, where intra and inter departmental commun

Determine the excitation threshold concerning neurons, How different are th...

How different are the concepts of action potential, resting potential and excitation threshold concerning neurons? Action potential is the maximum positive voltage level achiev

Define the meaning of population structure, Define the meaning of Populatio...

Define the meaning of Population Structure? The structure of population can be viewed as to how the population is composed of in terms of age and sex. The structure of populati

Person and being, What evidence is there that makes it seem humans have mor...

What evidence is there that makes it seem humans have more than a material existence?

Carbohydrates requirement in chronic diarrhoea, Q. Carbohydrates requiremen...

Q. Carbohydrates requirement in chronic diarrhoea? Adequate amount of carbohydrates i. e 60-65% of the total energy should be given to the patient. Easily assimilated carbohydr

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