Jejunum
The jejunum lies between the duodenum and the ileum and is considered to start at the suspensory muscle of the duodenum, a location called the duodenojejunal flexure. The division between the jejunum and ileum is not anatomically distinct due to the fact that in adult humans, the small intestine is usually 6-7m long, about two-fifths of which (2.5 m) is the jejunum.
Esophagitis
Esophagitis can be asymptomatic; or can cause epigastric and/or substernal burning pain, especially when lying down or straining; and can make swallowing difficult (dysphagia). The most common cause of esophagitis is the reverse flow of acid from the stomach into the lower esophagus: gastroesophageal reflux disease (GERD). 
The esophagus is a muscular tube made of both voluntary and involuntary muscles. It is responsible for peristalsis of food. It is about 8 inches long and passes through the diaphragm before entering the stomach. The esophagus is made up of four layers: from the inside out, they are the mucosa, submucosa, muscularis externa, and the serosa. The mucosa, the inner most layer and lining of the esophagus, is composed of stratified squamous epithelium, lamina propria, and muscularis mucosae. At the end of the esophagus is the lower esophageal sphincter, which normally prevents stomach acid from enteringthe esophagus.