Anatomy and function of the pharynx

Ramble about the pharynx, was bored and this beats revision :P

The pharynx lies posterior to the oral and nasal cavities, anterior to the cervical vertebrae it is superior to the larynx and extends up  to the soft pallet where it terminates, the walls of the pharynx are made up of skeletal muscle, lined with a mucous membrane, these muscles, when contracted cause the "swallowing" action and move particles such as food down towards the lowest point, and when relaxed, help to maintain the patency of the pharynx It is split into 3 different sections:
The Nasopharynx
The Oropharynx
and the laryngopharynx

The Nasopharynx sits posterior to the nasal cavity and is used as only as a passage way for air inhaled through the external nares, it extends down from the soft palet to the opening of the oropharynx.
The nasopharynx has 5 main openings through which air can pass in and out; the 2 internal nares, 2 openings lead to the auditory (or eustachian) tubes and the main opening to the oropharynx at its base, the posterior wall of the naso pharynx houses the pharyngeal tonsil (AKA the adenoid) The Walls of the nasopharynx are lined with Pseudo stratified columner epithelium- which are designed to "waft" and mucous or obstruction down towards the esophagus where it is swalled.

The second section, the Oropharynx, lies posterior to the oral cavity, it is used as a passage way for both; air coming from the nasopharynx, and air and food coming in through the oral cavity, it begins at the base of the nasopharynx and extends down inferior to the hyoid bone, the Oropharynx only has 1 main opening through which substances may enter from the external environment, the fauces (aka the throat), it is lined with non keratinized squamous epithelium, designed to protect the muscular walls from the abrasive action of food passing through on a regular basis (and protects against the acidity of potential vomiting) the oropharynx houses 2 pairs of tonsils: the palatine, and the lingual tonsils, which function to capture and large foreign bodies (dust, viruses etc.) thus protecting the lungs from infections.

Finally the laryngopharynx (aka hypopharynx) begins at the hyoid bone level and extends until its inferior end opens into the esophagus posteriorly and the larynx in the anterior direction, this means the the laryngopharynx, like the oropharynx prior to it, is used as a passage way for both food and air, and as such, is still lined with the non keratinized squamous epithelium,to protect its muscular walls from abrasions/ damage.

References:

G.J Tortora, b. D. (2011). Principles of anatomy and physiology. Asia: John Wiley and sons. Book 2

 R. L. Drake, A. W. (2010). Gray's Anatomy for Students. Philadelphia: Churchill Livingstone.

My brain

As i said, was something to do - couldn't be arsed doing full revision so wrote this exam answer :)

Liam

Out!