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
Terrestrial and Aquatic Ecosystem What is common between a terrestrial and an aquatic ecosystem. Both have similar type of trophic structure. They possess an autotrophic layer

what are the two alternate pathways to glycolysis

Can you use a regular syringe instead of a gas syringe in a lab

Write the positive ion isoelectronic with neon The positive ion isoelectronic with neon must have 10 electrons and 11 protons, and thus must have an  atomic number = 11. This i

Herbage area or vegetation cover Herbage area or vegetation cover is an important aspect of vegetation study in understanding the nature of a community particularly in evaluat

The common nitrogen-fixer in paddy fields is: 1. Rhizobium 2. Azospirillum 3. Oscillatoria 4. Frankia Azospirillum is the common nitrogen-fixer in paddy fields

What is paediatric clinical literature The paediatric clinical literature has expanded greatly in its coverage of the wide variety of medical circumstances that can negatively

Q Which are the extra abundant ribosomes in secretory cells - the free cytoplasmic ribosomes or those associated with the rough endoplasmic reticulum? Free cytoplasmic ribosome

gaseous exchange in man

How is the large size of some cephalopods related to the type of circulatory system they present? In cephalopods the circulatory system is closed and this gives more speed and