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

Oxidation of succinate to fimarate, Oxidation of  succinate  to  fimarat...

Oxidation of  succinate  to  fimarate:  This reaction is catalyzed  by succinate dehydrogenase and FAD'  is needed as a cofactor. Malonate, structural of succinate, competitively

What is infra-diaphragmatic type of tapvc, What is Infra-diaphragmatic Type...

What is Infra-diaphragmatic Type of TAPVC? Initial stages of operation are the same as for supracardiac type of TAPVC. The heart is lifted out of the pericardial cavity and c

Molecule synthesis and molecule break-down, Match dehydration reaction and ...

Match dehydration reaction and hydrolysis reaction to molecule synthesis and molecule break-down

What is bile salts, What is Bile salts Bile salts have a considerable...

What is Bile salts Bile salts have a considerable ability to lower surface tension. By  this property, they prevent  the coming together of the small fat droplets in  the  in

Explain the protein energy malnutrition (pem), Explain the Protein Energy M...

Explain the Protein Energy Malnutrition (PEM)? Protein Energy Malnutrition (PEM) is the deficiency of macronutrients or energy and protein in the diet and forms the most import

Was there molecular oxygen in the earths primitive atmospher, Was there mol...

Was there molecular oxygen in the earth's primitive atmosphere? How has that molecule become abundant? The presence of the molecular oxygen in the primitive atmosphere was prob

Medical and first aid, Medical and First Aid - Factors Affecting Occupation...

Medical and First Aid - Factors Affecting Occupational Health Depending on the type of work the industry must make arrangement for readily available medical facility. A nearby

Polyembryony, what are the types of polyembryony?

what are the types of polyembryony?

Simple tips to diarrhoea patient, A few simple tips which should be given t...

A few simple tips which should be given to the patient. • Boiling, steaming, baking, pressure cooking should be encouraged • Consume small and light meals frequently instea

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