The abdomen essentially contains the digestive system, from the stomach to the rectum. Note that the Osteopath systematically takes into consideration a structure called peritoneum which, like a bag, will include the viscera to attach to the bony walls. It consists of 2 sheets, a visceral around the organs and a parietal in contact with the bones, which delimits a virtual space called peritoneal cavity. This membrane, which forms folds by marrying the shape of the organs, has a role of maintaining and orientation of the organs, and can thus influence visceral biomechanics by retracting or relaxing.

In the order of progression of the food bowl, we will describe:

• The stomach, which is connected to the liver by the small epiploon (gastro-hepatic ligament).

The contraction of the gastric muscle (made up of 3 layers), for the mixing of food (remember that it is necessary for a good diet the 9 essential amino acids that are not synthesized by our body) is controlled by the nerve wave (X) mainly.

Between the stomach and the pancreas back, there is the omental bursa, also called the back cavity of the epiploons, which is bounded to the right by the Winslow hiatus between the lower cave vein back and the vein carries the liver pedicule forward (the pathway for the surgeon once the liver has been cleared); this space can be the seat of peritonitis in case of gastric ulcer.

• the duodenum, retroperitoneal (except for the first third of ^the first serving), with its 4 servings: the junction bet^ween the first duodenal portion and the stomach is called pylorus; it is a sphincter that opens and closes to deliver passage to the chyme when brewed in the gastric pouch which is an acidic medium.

The ^second serving receives the bile duct from the liver and its gallbladder, for the release of bile, and thus digest the fats.

The liver is the largest organ in the body (1.5 kgs) and acts as a real sponge that fills with blood oxygenated by the portal vein and the liver artery and empties its blood through the liver veins and the Lower Cave Vein (VCI) towards the right portion of the heart.

It is therefore richly vascularized, but does not contain nerves, which is the reason why it does not hurt, and does not inform us of its dysfunction.

The Osteopath systematically investigates the liver, because it is very frequently undulating to palpation, linked to the fact that it is infiltrated, congested (signing a hepatomegaly for example).

Osteopathy's manipulations are often enough to relieve congestion, working locally under the costal grill, but also by "unlocking" its vertebral projection at the D7/D8 level. He can also offer you a liver drainer, to be taken in the form of a cure for 1 month, containing thistle-marie, artichokes, desmodium, black radish…

The pathognomonic test is the one that involves pressing the MacBurney point, located at the outer third of the line connecting the right pelvis (EIAS right) to the umbilical. This may also reveal portal hypertension, thrombosis, or even cirrhosis, and the Osteopath will judge whether it is appropriate to refer the patient to his treating physician, who can ask for an abdominal ultrasound for example or an MRI to investigate the region and eliminate a potential more serious disease (e.g. autoimmune)

The ^second duodenal portion also receives the Wirsung canal from the pancreas to pour pancreatic juices at the water bulb (exocrine secretion), to neutralize the acid chyme, but it also has a function in regulating blood sugar by secreting in the bloodstream 2 hormones: insulin, hypoglycemic, and glucagon, hyperglycemic: it is endocrine secretion.

The ^third portion is limited backwards by the abdominal aorta and forward by the upper mesenteric artery, and can be pinched at this level: it is the syndrome of the aorto-mesenteric clamp.

The duodenum ends with the duodeno-jejunal junction (JDJ), which forms an angle, the opening for the passage of the food bowl is carried out by the Treitz ligament, or duodenal suspensor muscle, which joins the muscle fibers of the right pillar of the diaphragm.

• This results in the small intestine, an important digestion zone to absorb 90% of the nutrients essential to the body. Its average length is 6 meters. It accedes to the posterior abdominal wall by the mesentery, considered a real organ.

• Finally, the colon, or large intestine, which is 1.5 meters long and forms a frame from the caecum in the right iliac pit.

The ascending and descending colons are retroperitone, fixed on the posterior parietal peritoneum, thanks to the right and left Toldt fascias respectively.

On the contrary, the transverse colon is more mobile, looser. It is connected to the stomach by the large epiploon, it is t^{he f}irst structure under the abdominals, which the surgeon investigates when he opens the belly.

The left colic angle is higher than the right and located below the spleen.

This is the area of water absorption to form the faeces that will become more consistent. Excess absorption will cause the materials to stagnate, which can lead to constipation; conversely, a lack of water absorption, linked for example to spasms increasing peristalsis (progression of the faster food bowl), will instead create soft stools, it is diarrhea, whose main risk is dehydration.

It ends with the sigmoid colon, mobile and held by its meso which ensures its vascularization.

Note the presence of the spleen behind the stomach (connected by the gastro-splenic ligament), and above the left kidney…

At the nerves, it contains the lumbar plexus, consisting of sensory or mixed nerves (sensitive and motor), destined for the thigh muscles, the best known and the largest being the femoral nerve, or crural, which results from the meeting of the anterior twigs of the nerves coming out of the foramens of ^{the 2}n^{d, 3r}d, a^{nd 4}th lumbar vertebrae.

When it ignites, it creates the famous cruralgia, with pains called "scarf" radiating forward (quadriceps) and the inside of the thigh (adductors…)

At the orthosympatheic vegetative level is the celiac plexus, also called solar plexus (because its fibers "radiate" like a sun). It is located at the level of the dorso-lumbar hinge (D12/L1) in front of the abdominal aorta.

It is considered the 2^nd brain, as it contains neurons, especially in its 3 pairs of ganglia, celiac, upper mesenteric, and aortic, for the innervation of the diaphragm, liver, spleen, small intestine, gonads (testicles or ovaries), and finally kidneys and their adrenals.

Remember that the adrenal glands themselves act as a real sympathetic ganglion, secreting mainly adrenaline by the medullosurrenals and cortisol by corticosteroids in case of stress.