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

Contact guidance - modes of cell movement, Contact guidance - Modes of Cell...

Contact guidance - Modes of Cell Movement Besides chemical / ionic factors that regulate cell movement in developing embryos, physical factors as well appear to play a role in

Explain some physiological changes during pregnancy, Explain some Physiolog...

Explain some Physiological Changes during Pregnancy? A whole new life begins at conception. Organ systems develop rapidly and nutrition plays many supportive roles. Pregnancy f

Explain the endochondral ossification, Explain the endochondral ossificatio...

Explain the endochondral ossification The second type of osteogenesis is endochondral ossification. This process is different from intramembranous ossification in that it occur

Probation/parole client , Write a report on a special probation/parole clie...

Write a report on a special probation/parole client and programs that have been situated to address this problem client. Focus on 1type of special requires offender (substance abus

Where in the plants is a large amount of iaa found, Where in the plants is ...

Where in the plants is a large amount of IAA found? The Auxins are produced and found in large amount in the apical buds of the shoots and stem and in the young leaves.

Define methods of food preservation, Define methods of Food Preservation? ...

Define methods of Food Preservation? Food preservation is one of the oldest technologies used by human beings. The perishable food materials like fruits, vegetables, milk, meat

What is the name of the larval stage of polychaetes, Q. Is the embryonic de...

Q. Is the embryonic development in earthworms indirect or direct? The embryonic development is direct because in earthworms there is no larval stage. Q. What is the name of

Explain the recommended dietary allowances - nutrition, Explain the Recomme...

Explain the Recommended Dietary Allowances - Nutrition? The recommended dietary allowances are defined as the 'daily dietary intake level that is sufficient to meet the nutrien

Clinical manifestation and diagnosis of pericardiocentesis, Clinical Manife...

Clinical Manifestation Occurs over an extended time period and mimic those of CHF and corpulmonale. Dyspnea on exertion, dependent odema, ascitis, fatigue, anorexia and weight

Endocytosis, i have to make assignment on it. can u help me

i have to make assignment on it. can u help me

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