Mesentery

What is the mesentery?

The mesentery is an organ inside your abdomen that supports and is directly connected to all other abdominal organs in your digestive system.

The mesentery’s classification as an organ is new. For centuries, anatomy textbooks described the mesentery as many mesenteries (plural). The medical community viewed the mesenteries as several peritoneal tissues that attach your intestines to your abdominal wall. The peritoneum is a membrane that covers your abdominal cavity and abdominal organs.

In 2016, researchers Coffey et al. proved that the mesentery meets the criteria of an organ. An organ is a collection of tissues that forms a body part with an essential function. The mesentery is a single, continuous organ that physically supports your intestines. But it’s also an independent organ that nourishes your digestive abdominal organs and helps them work.

Research is ongoing about the mesentery’s function and its relationship to digestive system diseases.

What is the history of the mesentery?

What’s odd about this new discovery that the mesentery is a single structure is that it’s actually not new. In the 1500s, scientists such as Eustachius and Leonardo da Vinci depicted the mesentery in drawings as one continuous abdominal structure. But thinkers like Henry Gray — the doctor behind the textbook Gray’s Anatomy — helped popularize the idea that there were many mesenteries.

The 2016 research disproves this idea of multiple mesenteries. In many ways, this research signals a return to what scientists thought over 500 years ago.

What does the mesentery do?

Scientists are still learning about all the mesentery does. In the meantime, they know it provides structural support for your intestines. It nourishes your organs and serves as a signaling system that helps your digestive system function.

Secures and positions your abdominal organs

Your mesentery anchors parts of your intestines to your abdominal wall. It helps suspend other parts in three-dimensional (3D) space inside your abdominal cavity.

Without your mesentery’s support, your intestines would collapse inside your abdomen. If all the parts attached to your abdominal wall, your intestines wouldn’t have the room to contract (relax and squeeze) to move food along your digestive tract. They could twist, causing potentially life-threatening problems.

While scientists need more research to be sure, it’s also possible that the mesentery’s structure is an evolutionary feature that allows humans to walk upright. The mesentery’s structure in humans and primates that walk on two legs is different from its structure in animals that walk on all fours.

Helps your abdominal digestive organs develop and function

The mesentery forms before other digestive organs during fetal development. Other abdominal organs in your digestive system — including your liver, spleen, pancreas and intestines — all develop within your mesentery. Digestive organs remain connected to your mesentery after you’re born. The mesentery contains structures that support and nourish these organs throughout your life.

Serves as a signaling platform that enables individual organs to work as a system

Your abdominal digestive organs aren’t just physically connected to the mesentery. They’re also connected via shared nerves, blood vessels and lymph nodes within the mesentery. Lymph nodes are glands that filter substances throughout your body. These shared resources send and receive signals that allow individual organs to work together within your digestive system. Your mesentery helps your digestive system function within your body’s entire network of systems.

For example, lymph nodes in your mesentery trap germs from your intestines, like viruses and bacteria. They’re part of your immune system’s response to fight these invaders.

Your mesentery also makes C-reactive protein (CRP), a substance usually released by your liver. CRP helps regulate inflammation, your body’s healing response to injury and infection.

Where is the mesentery located?

The mesentery starts at the back of your abdominal cavity, where your superior mesenteric artery is. This artery supplies blood to your pancreas and intestines. Both the artery and the mesentery are mid-gut, near where the first vertebra of your low back is. Your mesentery extends from this mid-gut starting point in a spiral-like shape that spans your intestines and rectum.

What is the structure of the mesentery?

The mesentery’s structure is complex. Although it’s one continuous organ, various parts attach your intestines to the back of your abdominal wall. Other parts of the mesentery attach to your organs without connecting to your abdominal wall. This leaves organs secure — but with a little wiggle room — inside your abdominal cavity. Your mesentery’s many twists, turns and attachments secure your intestines while suspending them in 3D space inside your abdomen.

It can help to think of the mesentery’s structure in terms of its attachments to your abdominal organs and posterior (rear) abdominal wall.

• Small-intestinal mesentery. The mesentery travels from its mid-gut origin to attach to your small intestine.
• Right mesocolon. The mesentery runs from your small intestine to the right side of your large intestine (colon). This part of your mesentery secures the right part of your large intestine to your rear abdominal wall.
• Transverse mesocolon. The mesentery continues across your transverse colon. Your transverse colon is the horizontal part that extends across your abdomen.
• Left mesocolon. The mesentery attaches to the left side of your colon. Like the right mesocolon, the left mesocolon secures the left part of your large intestine to your rear abdominal wall.
• Mesosigmoid. The mesentery attaches part of your sigmoid colon to the rear abdominal wall. The sigmoid colon is the part of your colon closest to your rectum.
• Mesorectum. The bottom part of your mesentery attaches to your rectum.

For years, anatomy textbooks depicted multiple mesenteries surrounding the intestines while excluding the mesentery on the right and left sides (right and left mesocolon). Now, we know that the mesentery also exists in these areas.

This new understanding of the mesentery’s structure sheds new light on how organs develop from the mesentery. It can also inform approaches during surgery.

How big is the mesentery?

It’s huge. The adult mesentery is about 6 feet long when it isn’t compacted and spread out among your organs.

What is the mesentery made of?

The mesentery mostly consists of adipose tissue, or body fat. It’s the body fat that people associate with having a “beer belly” or a “gut.” The mesentery also contains connective tissue that holds the fat in place. It’s surrounded by a protective cell layer called the mesothelium. Connective tissue called Toldt’s fascia binds the mesentery to your abdominal wall.

The mesentery also contains several lymph nodes that play a key role in detecting and fighting germs.

What are the common conditions and disorders that affect the mesentery?

Much of the research about the mesentery involves new findings about Crohn’s disease. Crohn’s is an inflammatory bowel disease (IBD) involving harmful inflammation in your intestines. Research suggests that substances in the mesentery influence how the disease progresses. It’s also possible that Crohn’s disease starts in the mesentery and not in the intestines, as traditional thinking suggests. More research is needed to know for sure.

Most of your belly fat is in your mesentery. Belly fat includes subcutaneous fat that’s just underneath your skin. It’s the fat you can pinch with your fingers. Visceral fat (the kind that makes up your mesentery) is deeper inside your abdomen. Too much visceral fat increases your risk of multiple conditions, including:

• Diabetes
• High blood pressure (hypertension)
• Obesity
• Coronary artery disease
• Metabolic syndrome
• Stroke

Other diseases and conditions involving the mesentery include:

• Cancer. Cancer can start in your mesentery. Parts of tumors from your abdominal digestive organs can break off and spread to your mesentery.
• Infections. The lymph nodes inside your mesentery can detect germs. They can release immune cells to destroy them. Sometimes, germs “hide out” in the lymph nodes in your mesentery. When this happens, and your immune system doesn’t detect them, the germs can emerge later and cause problems.
• Sclerosing mesenteritis. Too much inflammation in your mesentery can damage or scar the tissue. The damaged tissue can cause the blood vessels in your mesentery to narrow or become blocked. This prevents blood flow and can cause life-threatening blood clots.
• Mesenteric panniculitis. This is an inflammatory condition in your mesentery similar to sclerosing mesenteritis. While sclerosing mesenteritis tends to worsen, mesenteric panniculitis tends to be more stable and less serious.
• Hernias. A hernia happens when an organ or tissue pushes through the cavity wall that contains it. Hernias affecting your mesentery can happen because of a congenital condition (present at birth). They can also occur as a complication after surgery on your abdominal organs.
• Malrotation. Malrotation happens when a fetus’s intestines don’t develop fully or coil properly. (The shape and position of your intestines depend largely on how the mesentery develops.) Once the baby’s born, they’ll need surgery on their intestines and mesentery to position these organs correctly.
• Volvulus. Malrotation can lead to volvulus. With volvulus, your small or large intestine and mesentery twist abnormally. This usually happens when the mesentery isn’t securely attached to your abdominal wall. The twisting can create a blockage in your large or small intestine. The blockage can prevent blood from reaching your intestine. It’s an emergency situation that requires fast treatment.

Given how closely related the mesentery is to all your abdominal digestive organs, it’s likely that any disease that affects a digestive organ also involves the mesentery. Research is ongoing to learn more about the mesentery’s role in various digestive system diseases.

What are common treatments for the mesentery?

Recent research suggests that procedures used to treat abdominal organs should also include the nearby mesentery. For example, some studies show that removing certain areas of the mesentery can slow the progression of Crohn’s disease. Other studies show that removing the nearby mesentery can decrease the odds of colon cancer returning.

New knowledge of the mesentery can also inform approaches to abdominal surgeries. Previously, surgeons operated on organs within the abdomen in relationship to multiple mesenteries. They understood these mesenteries as complex parts: sacs, recesses, pouches and cavities. The mesenteric model divides the abdomen into basic parts: the abdominal region that includes the mesentery and the region that doesn’t.

This more simplified understanding of the abdomen’s structure can potentially make for more straightforward approaches during surgery.

How can I care for my mesentery?

One of the best things you can do to care for your mesentery involves having a healthy amount of visceral fat. Too much visceral fat in your mesentery can increase your risk of chronic conditions like heart disease.

You can reduce your visceral fat by:

• Limiting certain foods. This includes trans fats, sugar (including corn syrup), sodium and processed foods. Try to limit candy, soda and fried foods. Also, curb your alcohol intake.
• Exercising regularly. Aim for at least 150 minutes of moderate-intensity exercise each week.
• Getting enough sleep. Research has shown that not getting enough high-quality sleep each night can cause you to gain visceral fat. Aim for eight or more hours of sleep each night.
• Manage stress. Stress causes your body to release the hormone cortisol. Over time, increased cortisol levels can cause you to gain belly fat. Managing stress is not only good for your mind but good for your physical health, as well.