Location and structure of the small intestine – the small intestine (intestinum tenue) is the longest section of the digestive tract (approx. 5-7 metres), located between the stomach and the colon; it consists of three parts: the duodenum, the jejunum and the ileum.
The small intestinetissue layers, from the inside outwards, are as follows: the mucosa (consisting of the absorptive epithelium, the connective tissue layer beneath the epithelium and the epithelium's own muscle layer), the submucosa (the connective tissue layer between the mucosa's own muscle layer and the true muscle layer, in which the glands of the small intestine/Brunner's glands/ are also found), the muscle layer (inner circular and outer longitudinal) and the serosa (the peritoneal layer covering the small intestine).
The latter layer is missing from the initial section of the duodenum, because here the duodenum runs in the space behind the peritoneum.
