Abdominal pain

Abdominal pain arising from the alimentary canal is of two types.

1.       Visceral pain. The alimentary tract is primarily a midline structure with a bilateral nerve supply. Although rotation about the midline occurs during development, nevertheless true visceral pain is referred to the midline as shown in Fig. 57.1. It is dull and poorly localised. For example, an obstructing stenosis of the terminal ileum, which is part of the midgut, would give rise to colicky periumbilical pain.

2. Peritoneal pain is of the somatic type and is much more precise, more severe and localised to the site of origin. These components account for the changes in character and site of pain which occur in appen­dicitis. Once the full thickness of the appendicular wall becomes inflamed the overlying peritoneum becomes involved and the patient has localised right iliac fossa pain (see Chapter 59).

Surgical anatomy

It is of great practical importance to be able to do the following:

1.distinguish various portions of the intestinal tract at sight;

2.know in which part of the abdomen the upper coils, as opposed to the lower coils, of small intestine lie in relationship to the anterior abdominal wall;

3.be able to decide which is the proximal and which is the distal end of any coil under consideration;

4. distinguish irrefutably large from small intestine.

  The following are useful tips.

The mesentery of the jeiunum has only two series of arcades of blood vessels, whereas the lower ileum has several series of arcades.

The mesenteric attachment runs from left to right. Provided that the gut is not twisted, the proximal small bowel lies in the upper part of the abdomen and the lower small bowel lies in the lower part of the abdomen.

The large intestine can be characterised by its taenia coli and appendices epiploicae.