Human Abdominal Cavity

The vagus nerve (pronounced /ˈveɪɡəs/, US dict: vā′·gəs), also called pneumogastric nerve or cranial nerve X, is the tenth of twelve (excluding CN0) paired cranial nerves. Upon leaving the medulla between the olivary nucleus and the inferior cerebellar peduncle, it extends through the jugular foramen, then passing into the carotid sheath between the internal carotid artery and the internal jugular vein down below the head, to the neck, chest and abdomen, where it contributes to the innervation of the viscera. Besides output to the various organs in the body, the vagus nerve conveys sensory information about the state of the body's organs to the central nervous system. 80-90% of the nerve fibers in the vagus nerve are afferent (sensory) nerves communicating the state of the viscera to the brain.[1]
The medieval Latin word vagus means literally "Wandering" (the words vagrant, vagabond, and vague come from the same root). Sometimes the branches are spoken of in the plural and are thus called vagi (pronounced /ˈveɪdʒaɪ/, US dict: vā′·jī). The vagus is also called the pneumogastric nerve since it innervates both the lungs and the stomach.

The ileum (English pronunciation: /ˈɪlɪəm/) is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum.[2]
The ileum follows the duodenum and jejunum and is separated from the cecum by the ileocecal valve (ICV). In humans, the ileum is about 2-4 m long, and the pH is usually between 7 and 8 (neutral or slightly alkaline).

Difference Between Ilium and Ileum

by Angie on September 6, 2010
Very simply, ilium refers to a bone and ileum refers to small intestine.
Ilium – a bone in the pelvis. The bony pelvis, upper part, forms the receptacle for the femur head at the hip joint.
Ileum – also known as a portion of the small intestine. It is located just before large intestine, beyond duodenum and jejunum, and is the lowest part of small intestine.


The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal (or coelomic) organs — in higher vertebrates and some invertebrates (annelids, for instance). It is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum both supports the abdominal organs and serves as a conduit for their blood and lymph vessels and nerves.


The abdominal cavity (the space bounded by the vertebrae, abdominal muscles, diaphragm and pelvic floor) should not be confused with the intraperitoneal space (located within the abdominal cavity, but wrapped in peritoneum). For example, a kidney is inside the abdominal cavity, but is retroperitoneal.
Although they ultimately form one continuous sheet, two types or layers of peritoneum and a potential space between them are referenced:
  • The outer layer, called the parietal peritoneum, is attached to the abdominal wall.
  • The inner layer, the visceral peritoneum, is wrapped around the internal organs that are located inside the intraperitoneal cavity.
  • The potential space between these two layers is the peritoneal cavity; it is filled with a small amount (about 50 ml) of slippery serous fluid that allows the two layers to slide freely over each other.
  • The term mesentery is often used to refer to a double layer of visceral peritoneum. There are often blood vessels, nerves, and other structures between these layers. The space between these two layers is technically outside of the peritoneal sac, and thus not in the peritoneal cavity.


The ileocecal valve is a sphincter muscle situated at the junction of the small intestine (ileum) and the large intestine. Its critical function is to limit the reflux of colonic contents into the ileum.[1]
The ileocecal valve is distinctive because it is the only site in the GI tract which is used for Vitamin B12 and bile acid absorption.
Functionally, roughly two litres of fluid enters the colon daily through the ileocecal valve.

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