Anatomy clinical correlates: Anterior and posterior abdominal wall

When we think about the clinical conditions affecting the abdomen, we immediately think about injury to organs such as the liver, intestines or stomach. However, there are also many conditions that affect the anterior and posterior abdominal wall, as well as the structures adjacent to them. So let's get started!

When examining the gastrointestinal system, first, it’s important to do a general inspection of the abdomen which includes looking for scars and incisions which can indicate what surgeries the patient has had in the past. Typically, the location of the abdominal incision indicates what type of surgery the patient has had.

First, there’s the Kocher incision, also called the subcostal incision, which is made parallel and at least 2.5 centimeters below the costal margin in order to avoid the 7th and 8th thoracic spinal nerves. Injury to these nerves results in decreased sensation of the anterior abdominal wall supplied by those respective branches. This type of incision is usually found on the right side and provides access to the gallbladder and biliary ducts, and can be extended towards the left side of the abdomen to access the spleen.

Next up, there are longitudinal incisions, which include midline incisions and paramedian incisions. They can be used in almost all abdominal surgeries, especially exploratory surgeries which are sometimes needed to diagnose uncertain abdominal pathologies. Now, longitudinal incisions provide great exposure of the abdominal viscera and can also be extended as needed.

The midline or median incision is made along any part or length of the linea alba, so from the xiphoid process all the way towards the pubic symphysis. This type of incision is preferred because the linea alba only has small vessels and nerves, so there’s a lower risk of bleeding and nerve damage.

A paramedian incision, which is lateral to the median plane, is made in a sagittal plane and can extend anywhere from the costal margin to the pubic hairline. The paramedian incision would therefore go through the anterior rectus sheath, the rectus abdominis muscle, and the posterior rectus sheath.

Other surgical procedures may require oblique incisions, depending on muscle fiber orientation and surrounding nerves. Oblique incisions include the McBurney, or Gridiron incision, and the Rutherford Morison incision.