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 are the main structures of chloroplasts, What are the main structures ...

What are the main structures of chloroplasts? Chloroplasts are included by two membrane layers, the outer and the inner membranes. Inside the organelle the formative unit is kn

The deficiency in hepatic glucose 6 phosphatase, Under fasting conditions, ...

Under fasting conditions, individuals with a deficiency in hepatic glucose 6 phosphatase cannot dephosphorylate glucose 6 phosphate generated from liver glycogenolysis. As a result

What are the glucagon receptors in the plasma membranes, Which of the follo...

Which of the following serves as an effector, or as part of an effector, that functions in a negative feedback system? A. Glucagon Receptors in the plasma membranes of alpha-is

Explain intensity of heart sound, Explain Intensity of heart sound? Int...

Explain Intensity of heart sound? Intensity of S 1, particularly M 1 depends on the position of the bellies of mitral leafets when the LV begins to contract since S 1 is loudes

How would contrast single covalent bonds, 1. In modern blimps, the gas of c...

1. In modern blimps, the gas of choice used to inflate them is helium rather than hydrogen. Hydrogen would be lighter, but helium is safer. Compare and contrast the atomic structur

List out the different preservation techniques, List out the Different Pres...

List out the Different Preservation Techniques? The different preservation techniques commonly used today are given in the Table. Table: Methods of food preservation a)

Explain gelation - function of proteins, Explain Gelation - Function of pro...

Explain Gelation - Function of proteins Gelation  refers to the process where denatured molecules aggregate to form an ordered protein network. Proteins  can form a well-order

Periannular extension of infection, Occur in 10 per cent to 40 per cent of ...

Occur in 10 per cent to 40 per cent of all native-valve IE, and complicates aortic IE more commonly than mitral or tricuspid IE. Periannular infection is of even greater concern wi

Define diagnostic criteria for bulimia nervosa, Define Diagnostic Criteria ...

Define Diagnostic Criteria for Bulimia Nervosa? 1. Recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following a) Eating, in a d

Explain pyridoxal phoshphate, Pyridoxal phoshphate Pyridoxal  phosphate...

Pyridoxal phoshphate Pyridoxal  phosphate  is  derived  from  pyridoxine  (vitamin  B6)  and  is involved in amino acid metabolism.  The  other  two  compounds,  pyridoxal  and

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