 Welcome back to another video. This time we'll be discussing the general anatomy of the human gastrointestinal tract. You'll need a good understanding of the structures and functions of the various elements of the GI tract for your exams. This video will give you the strong foundation that you need to answer all kinds of GI questions for USMLE Step 1. When you learn the anatomy of the GI tract, make sure you focus not only on the structure and location of each organ, but also on the relationship in space to other surrounding organs and structures. You'll often get questions that require you to know about the spatial relationships between various structures in the GI tract and abdomen. Now before discussing the individual organs of the GI tract, we have to make a distinction between the upper GI tract and the lower GI tract. The landmark that divides the upper from the lower GI tract is the ligament of trites. The ligament of trites is also known as the suspensory ligament of the duodenum. On this diagram, you can see the general shape of the duodenum. We'll have a separate video specifically on the duodenum and its various parts, but for now, the ligament of trites attaches to the duodenum right about here. The ligament of trites attaches to the distal duodenum on one end, and this end up here attaches to part of the retroperitoneum. There's a clinical significance to distinguishing the upper from the lower GI tract, particularly when describing the source of a GI bleed. The upper GI tract is composed of the mouth, esophagus, stomach, and parts of the duodenum that are proximal to the ligament of trites. While the lower GI tract is composed of the remainder of the duodenum, the jejunum, the ilium, the colon, the rectum, and the anus. Of course, there are other organs that are part of the GI system, but not part of the GI tract, such as the salivary glands, pancreas, liver, and gallbladder, which we'll discuss in further videos.