Pharynx and larynx, Biology

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.  

Posted Date: 10/27/2012 7:41:01 AM | Location : United States







Related Discussions:- Pharynx and larynx, Assignment Help, Ask Question on Pharynx and larynx, Get Answer, Expert's Help, Pharynx and larynx Discussions

Write discussion on Pharynx and larynx
Your posts are moderated
Related Questions
Q. Most insects have wings. Which is the other animal phylum that contains creatures with analogous organs? Besides the phylum Arthropoda another animal phylum with flying crea

what is he importance of proteins for living beings

Explain the Disadvantage of Contact Plate Method? These plates are suitable for sampling the surfaces having low contamination, like pre-cleaned and sanitized surfaces. This is

Locomotion in Arthropoda The Arthropods are characterized by the existence of some special features which can be considered key to their success. These involve a rigid exoske

Q. Plant classification according to Ancient Greeks and Romans? Hippocrates, "The Father of Medicine" (460-377 B.C.) is reputed to have been one of Democritus 's disciples. He

Does mitosis properly occur before or after the interphase? Is it a mere "point of view" issue? Mitosis must be considered a succeeding phase after interphase since this

Q. How Implant design and surface affect osseointegration? Implant design Most conductive design for osseointegration is root form. They can be threaded, hydroxyapatite co

CONJUG A TE D PROTEINS Besides being made of polypeptides, the conjugated proteins posses additional groups, metals or ions. Consists of protein and non-protein parts.

HOW ARE THE ORIGIN AND EVOLUTION OF ALGAE..

What is the excretory organ of an agama lizard?