Duodenum

The duodenum is the final segment of the Small intestine (duodenum + Jéjunum + Iléon). It makes following the Estomac via the Pylore. It is the only mobile segment of this small intestine, the remainder being fixed with a peristaltic activity (contractile) permanent.

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

General situation

The duodenum, body deep , is coupled with the posterior Péritoine parietal. It is projected on the lumbar vertebrae L1 with L4, and is plated against the rachidian block. It is crossed by the root of the transverse Mésocôlon 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, the tallies duodénal , divisible in 4 segments, separated by more or less acute angles:

  • D1 : it makes following the Pylore, on the right side of the 1st lumbar vertebra. It is oblique to the top and the line, slightly behind. It is bent then downwards with an acute angle, the genu superius of 80°.
  • D2 : it is a vertical segment , going down on the right side from the rachis. It extends from L1 with L4 and receives the biliary channels and pancreatic. It is bent with an angle of 90°, the genu inferius .
  • D3 : it is a horizontal portion 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 strictly speaking but only of one curve.
  • D4 : it is the ascending part final 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: the 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 portion initial of D1, or bulb duodénal , pathological in the Ulcer 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 the higher Vessels mesenteric.

Internal configuration

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

  • the séreuse or Peritoneum.
  • the musculeuse made up of 2 layers:
*longitudinale external
*circulaire deep
  • the submucosa , loose fabric.
  • the mucous , which papers the inner face and present folds and glands (Glandes of Brünner above the hépato-pancreatic bulb of Vater).

The mucous of the duodenum is folded. These folds form a pyloric valvule between the duodenum and the Estomac. Initially rather longitudinal in the upper part, they is rather transverse in the lower part of the duodenum.

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

  • the the minor duodenal papilla , highest, with the junction of the 1/3 superior and the 2/3 inferiors of D2. It recovers the meeting of the additional pancreatic Canal.
  • the greater duodenal papilla , located 3 cm in lower part, more important and broader. It recovers the hépato-pancreatic bulb.

Vascularization

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

Simple: Duodenum

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