We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is the Duodenum?

Niki Acker
Updated Mar 03, 2024
Our promise to you
The Health Board is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At The Health Board, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The duodenum is a short portion of the small intestine connecting it to the stomach. It is about 10 inches (25 cm) long, while the entire small intestine measures about 20 feet (6.5 meters). This structure begins with the duodenal bulb, bordered by the pyloric sphincter that marks the lower end of the stomach, and is connected by the ligament of Treitz to the diaphragm before leading into the next portion of the small intestine, the jejunum.

There are four distinct parts to the duodenum, the first three forming a "C" shape. It begins with the superior duodenum, which extends from the pyloric sphincter laterally to the right and posteriorly for about 2 inches (5 cm). The next section, the descending duodenum, is the middle of the "C". The inferior duodenum passes laterally to the left, and the last portion, the ascending duodenum, joins the jejunum at the duodenojejunal flexure.

Though the portion is such a tiny fraction of the small intestine, it is the site of most of the breakdown of the food passing through it. It is lined with Brunner's glands, which secrete an alkaline mucus that supports the intestinal enzymes and aids in the absorption of nutrients. The pancreatic duct, which introduces bile and pancreatic juice into the small intestine, is directly connected to the descending duodenum. Pancreatic juice contains enzymes that help break down food, while bile aids in the digestion and absorption of fats. This part of the small intestine is responsible for secreting hormones that trigger the pancreatic duct to release pancreatic juice and bile.

The duodenum also serves to neutralize the acidity of the chyme that exits the stomach, an intermediate product in the digestive process. Both the Brunner's glands and the pancreatic duct secrete alkaline fluids to temper the acidity of the chyme. In addition, the mucus secreted by the Brunner's glands helps protect the duodenum from the acidity, making it much less sensitive than the rest of the small intestine to the material. This allows it to help protect the rest of the small intestine by neutralizing the chyme to some extent before it passes into the jejunum.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Niki Acker
By Niki Acker , Writer
"In addition to her role as a The Health Board editor, Niki Foster is passionate about educating herself on a wide range of interesting and unusual topics to gather ideas for her own articles. A graduate of UCLA with a double major in Linguistics and Anthropology, Niki's diverse academic background and curiosity make her well-suited to create engaging content for WiseGeekreaders. "

Discussion Comments

By anon977094 — On Nov 07, 2014

Is there such a thing as a Duodenum blood clot and how dangerous could it be? --Don

By anon117915 — On Oct 12, 2010

my daughter had an upper Gi endoscopy and in her letter it says no major significant abnormality seen. histology of duodenum and stomach with significant abnormalities. can anyone transfer this in laymen's terms please?

However, she is allergic to milk and soya and has other food allergies.

By endoscopic10 — On Sep 11, 2010

my mother has some stomach aches as well as no taste in her mouth. we did one medical investigation called endoscopic particulars like Procedure: OGD, Indication N/A, and medication: Xylocaine, 10 percent spray. After that report showed: Esophagus: normal, Stomach: normal, duodenum: Normal up to the second part. Biopsy: Not done. Comments: Normal upper G.I. tract at endoscopy.

my question is, as we know, the duodenum has four distinct parts, so why didn't it show the present status of the other two parts of the duodenum? Is there something wrong which made her lose her appetite? As a result, she has become weaker and weaker day by day. She is also a diabetic patient for 18 years. Fortunately, her diabetes is under control. in this situation, any useful suggestion would be highly appreciated and I would be grateful to you.

By anon86679 — On May 26, 2010

I would like to know what happened with #25 -- the person whose sister had a perforation of the duodenum. This happened to my daughter and she is now out of breath.

By anon71047 — On Mar 17, 2010

anon16655: I lost my wife with this cancer. I wish you all the luck. Choose a good hospital and be very careful about blood clots; tha't what did her in. I am still so sad.

By bestcity — On Feb 08, 2010

The suffix -ase- when attached to the root of a word means enzyme.

By anon64138 — On Feb 05, 2010

what does -ase and the end of a word indicate?

By anon56268 — On Dec 13, 2009

my sister was found to have a perforation of the duodenum. she is in icu, having found a severe infection.

By anon53801 — On Nov 24, 2009

How could a person vomit fecal matter? This happened to my elderly mother before she died and I cannot understand what went wrong with her.

By anon47555 — On Oct 05, 2009

I have to do a stupid project about the digestive system.

By anon35898 — On Jul 08, 2009

Why would a feeding tube need to be placed in the duodenum as opposed to the stomach if the pt has esophageal cancer?

By God — On Jun 22, 2009

I lost my duodenum several years ago when I was just four years of age. I am twenty three now and I have not had a duodenum since then. What do you think about that?

By anon27033 — On Feb 23, 2009

I have recently been told by a physician that the duodenum, thyroid, and pituitary glands work together and specifically need eachother to work properly. This discussion was a result of severe cramping in the duodenal area, linked to the function of my pituitary. Does anyone have any information relevant to this connection?

By adabelle — On Feb 06, 2009

If you have cancer in the duodenum, is an operation likely? If so, what is the prognosis? And what happens afterward?

By timewise — On Oct 07, 2008

Are there papers regarding removal of the duodenum and its effect?

By anon18187 — On Sep 16, 2008

Is too much mucus in the duodenum a bad thing?

By anon16655 — On Aug 11, 2008

If you have cancer in the duodenum, is an operation likely? If so, what is the prognosis? And what happens afterwards?

By w17342 — On Apr 22, 2008

I recently heard about disconneting the duodenum to reverse diabetes. Where can I get more info on this. If it is true I would consider this. I have type 2 disbetes.

Thank You,


By anon11689 — On Apr 21, 2008

How and why does gastric bypass eliminate diabetes? I saw on 60-Minutes yesterday that people left the hospital in four days and were off their meds entirely and have had no trace of diabetes since.

By leilani — On Apr 21, 2008

In gastric bypass surgery bigger part of the stomach and duodenum are sealed off. Food enters the second part of intestines, jejunum, and as a result, fewer calories are absorbed.

It appears that duodenum plays a big part in type two diabetes. Some studies show that when duodenum is bypassed, diabetes disappears too.

By anon11407 — On Apr 16, 2008

(while bile aids in the digestion and absorption of fats)

this is too general. the bile emulsifies the fats only. because the starches are broken into polysaccrides in the mouth, and proteins are broken into polypeptides in the stomach by pepsin(not hydrochloric acid.)


By anon4235 — On Oct 08, 2007

This article really helped me complete a biology worksheet that i had to finish for class. It gives great details, and it's easy for me, a tenth grader, to follow.

Niki Acker

Niki Acker


"In addition to her role as a The Health Board editor, Niki Foster is passionate about educating herself on a wide range...
Learn more
The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.