Duodenum

duodenum is the initial segment of (duodenum + jejunum + iléon). It follows upon by the intermediary of pylore. It is the only fixed segment of this small intestine, the remainder being mobile with a peristaltic activity (contractile) permanent.

The duodenum has a very intimate anatomical relationship with : the traditional comparison is that of a tire around a rim.

General situation

The duodenum, body deep, is coupled with pariètal posterior. It is projected on the lumbar vertebrae L1 with L4, and is plated against the rachidian block. It is crossed by the root of mésocôlon transverse thus belongs at the same time on the floors known and under-mésocôliques. In fact, only the duodéno-pancreatic block is with horse on these two stages.

External configuration

The duodenum is a ring open in top and on the left, it tally duodénal, divisible in 4 segments, separated by more or less acute angles:

• D1 : it follows upon pylore, on the right side of the 1^Re lumbar vertebra. It is oblique to the top and line, slightly behind. It is bent then downwards with an acute angle, it genu superius of 80°.
• D2 : it is a segment vertical, going down on the right side from the rachis. It extends from L1 with L4 and receives them bile ducts and pancreatic. It is bent with an angle of 90°, it genu inferius.
• D3 : it is a portion horizontal pre-vertebral which follows a concave curve behind. Between D3 and D4 the angulation is marked very little, it is not a question of an angle to be strictly accurate but only of one curve.
• D4 : it is the part ascending final of the duodenum, on the left side edge of the rachis, of L4 with L2. It ends in a downwards open acute angle with the first jejunal handle, the duodéno-jejunal angle or angle of Treitz, in connection with the muscle which is fixed at it: muscle of Treitz or muscle hanger of the duodenum.

Dimensions

• Length : 25 to 30 cm (D1: 4 cm + D2: 10 cm + D3: 8 cm + D4: 6 cm)
• Gauge : 4 cm
• Two dilated portions :

• The initial portion of D1, or bulb duodénal, pathological inulcerate duodénal, very frequent.
• The segment of D2 downstream from the meeting of the bile and pancreatic ducts.

• Two contractings :

• On the level of D2, above the meeting of the bile and pancreatic ducts.
• On the level of D3, due to the passage of higher vessels mesenteric.

Internal configuration

The structure of the duodenum is divided into 4 layers which are of outside in inside:

• séreuse or .
• musculeuse composed of 2 layers:

• longitudinal external
• deep circular

• submucosa, loose fabric.
• mucous membrane, which papers the face interns and present folds and glands (glands of Brünner abovehépato-pancreatic bulb (of Vater)).

mucous membrane duodenum is folded. These folds form one pyloric valvule between the duodenum and it. Initially rather longitudinal in the higher part, they are rather transverse in the lower part of the duodenum.

There is two mucous projections on the face interns of D2, components of the mucous folds compared to the meeting of the bile and pancreatic ducts:

• minor papilla duodénale, highest, with the junction of the 1/3 superior and the 2/3 inferiors of D2. It covers the meeting with additional pancreatic channel.
• major papilla duodénale, located 3 cm below, more important and broader. It covers the hépato-pancreatic bulb.

Vascularization

Because of their reports/ratios intimate it is superposable with that of the head of .