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

What is ascaris and which disease caused by this worm, Q. What is ascaris? ...

Q. What is ascaris? What is the disease caused by this worm? Ascaris lumbricoides or Ascaris is an animal of the nematode phylum that is a roundworm. Ascaris causes ascariasis,

Do fats with one or more ''kinky'' tail fatty acids, Do fats with one or mo...

Do fats with one or more 'kinky' tail fatty acids tend to be solid or liquid at room temperature? These are found in triglycerides forming what? Solid fats or oils? Is it opposite

Protein, What''s the classification of simple protein?

What''s the classification of simple protein?

Define prognosis of eating disorders, Define Prognosis of Eating Disorders?...

Define Prognosis of Eating Disorders? About 50% of the patients recover fully from anorexia nervosa and achieve normal weight, 30% improve but have a partial recovery and 20% w

What is form sense, What is Form Sense Form Sense is the  faculty which...

What is Form Sense Form Sense is the  faculty which  enables us  to perceive the  shape of  objects in  the  outer world. Here  the cones play  predominant part, and  the  form

Viral genome, describe the different types of genomes that viruses can have...

describe the different types of genomes that viruses can have

Define importance of bioelectrical impedance analysis, Define Importance of...

Define Importance of Bioelectrical impedance analysis? Bioelectrical impedance analysis (BIA) is a rapid, non-invasive and relatively inexpensive method for evaluating body com

Explain the two forms of hemicellulose, Explain the two forms of hemicellul...

Explain the two forms of hemicellulose There are two forms of hemicellulose - Hemicellulose A and B - Hemicellulose A is precipitated upon neutralization of an alkaline extract

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