Describe pharynx, oesophagus and external structure of stomach of digestive track of human beings.

Explanation

(a) Pharynx : The oesophagus and the trachea open into pharynx.
Pharynx is located behind Nose, mouth and larynx. It is divided into three parts.
(i) Nasopharynx
(ii) Oral pharynx
(iii) Laryngeal pharynx
Function : It helps to swallow food. It sends food in oesophagus.
A cartilaginous flap called epiglottis prevents the entry of food into the glottis.
(b) Oesophagus : Oesophagus is a thin, long tube. It is behind trachea and in the front of vertebral column. It extends posteriorly passing through the neck, thorax and diaphragm and leads to .J. shaped bag like structure called stomach.
A muscular sphincter regulates the opening of oesophagus into the stomach.
Function : It sends food into stomach.
(c) Stomach : The most enlarged part of digestive tract is stomach. The stomach is located in the upper left portion of the abdominal cavity. It has three parts:
(i) Cardiac Stomach : Oesophagus opens into it.
(ii) Fundus : It is the main part of stomach.
(iii) Pyloric Stomach : It is a transverse part of stomach. Stomach is connected to duodenum by oesophagus and pyloric stomach through cardiae stomach. It opens into first part of small intestine.
Function : Stores food temporarily, food gets churned and converts into chyme.