Abdomin

Anatomy

The Abdomen
The spleen
It is a lymphatic organ, located in the left hypochondrial region, post. to the upper part of the stomach. It rests on the left colic flexure & phrenicocolic lig. (sustentaculum lienis). It averagely measures 12cm long & 7cm broad. Normally the spleen does not descend below the costal margin & it is seldom palpable through the abd. wall unless it is enlarged.
The spleen is completely peritonized. It is attached to the stomach, diaphragm and left kidney by gastrolienal phrenicolienal lienorenal lig. respectively.
The spleen has 2 surfaces: diaphragmatic & visceral surfaces.
The diaphragmatic surface is convex & fits the diaphragm, it is directed post.lat. and is related to 9th , 10th& 11th ribs.
The visceral surface is triangular in shape, directed anteromedially.
*The apex is directed superiorly, medially & posterior. The base is directed inferolaterally and anterior.
*The base is flattened surface, & makes contact with left colic flexure.
*The superior border is directed laterally, & it is thin & notched.
*The inferior border is directed medially & it is smooth & rounded.
* Impressions on the visceral surface:
a slight ridge extends from the apex to the middle or center of the spleen.( splenic ridge )
superolateral to the ridge is the gastric impression.
inferomedial to the ridge is the renal impression.
in between these two impressions (nearly in the center of the spleen) we have the hilum, formed of a series of indentations ( which are the sites of entrance & exit of splenic arteries & veins).
the lower part of the hilum is occasionally in contact with the tail of pancreas.
above the base we have a colic impression.
Blood supply:
By the splenic artery: it divides into mainly 4 branches, which enter the spleen separately. The proper splenic veins unite forming the splenic vein which is not tortuous & lies behind pancreas inf. to the splenic artery.
Lymphatics:
To pancreaticolienal lymph nodes along the splenic vessels.
Nerve supply:
From celiac plexus (sympath. and parasympath.).


Duodenum:
It is the 1st part of small intestine, about 25cm long & has a C shape.
The duodenum is divided into 4 parts :
The 1st (superior) part of duodenum:
It is about 5cm long. It passes from pylorus posteriorly along the right side of the body of L1 vertebra. This part is completely peritonized (by less. oment.).
Relation:
ant. : quadrate lobe of liver & gallbladder. (It makes contact with neck of gall bladder).
Post. : gastroduodenal artery, common bile duct & portal vein.
Inf. : head of pancreas.

The 2nd (descending) part of the duodenum:

It is about 8cm long. It descends along the right side of L1 , L2 & L3 vertebrae. It is a fixed retroperitoneal part (having fusion fascia behind).
Relation:
Ant. : fundus of gallbladder & this part crossed by transverse colon.
Post. : hilum of Rt kidney, Rt renal vessels , Rt ureter.
Med. : head of pancreas.
Lat. : Ascending colon & right colic flexure.
At the junction of the middle & lower thirds of this part of duodenum, the common bile duct & the pancreatic duct penetrate the posteromedial wall to open on the summit of the greater duodenal papilla (ampulla of Vator)

The 3rd (inferior) part of duodenum:

It is about 7cm long. It crosses the lower part of the body of L3 vertebra from its right to its left side. This part is retroperitoneal.
Relation:
Post. : inf. vena cava, aorta & right testicular (or ovarian) vessels.
Ant. : root of mesentery & within it the sup. mesenteric vessels cross this part of duodenum.
Sup. : head of pancreas.
Inf. : coils of jejunum.


The 4th part (ascending) part of duodenum:
It is about 5cm long. It ascends on the left side of vertebrae as far as the upper border of body of L2 vertebra.
The end of duodenum is covered by peritoneum & it is movable, but most of the 4th part is retroperitoneal.
The 4th part turns abruptly forward to become continuous with the jejunum at the duodenojejunal flexure. The root of mesentery begins at this flexure & then passes to the right side crossing the 4th part of duodenum. The duodenojejunal flexure is stabilized by a fibromuscular band, the suspensory muscle of duodenum (ligament of Treitz), which attaches the duodenum to the Rt crus of diaphragm.
Relation:
Ant. : root of mesentery.(mentioned above )
Post. : left side of aorta & the left testicular (or ovarian) vessels.

The pancreas:

Elongated structure lies transversely across the post. abd. wall from the duodenum to the spleen behind the stomach. It is a retroperitoneal organ with fusion fascia behind.
The pancreas is divided into : head, neck, body & tail.
Head of pancreas:
The larger part, occupying the C - shaped circle of duodenum, separated from duodenum by the pancreatic sulcus.
*Anteriorly the head is crossed by transverse mesocolon.
*Posteriorly the head overlies the inf. vena cava, renal veins, right renal artery & (aorta behind the uncinate process).
The lower left portion of the head is located behind the sup. mesenteric vessels forming the uncinate process.
The common bile duct descends diagonally behind the head of pancreas.

Neck of pancreas

The constricted part, it is continuous with the upper left portion of the head.
*Posteriorly it is grooved by the sup. mesenteric vessels, also behind the neck, the sup. mesenteric vein & splenic vein unite to form the portal vein.
*The anterior surface of the neck is continuous with the ant. surface of the body of pancreas & lies in the floor of omental bursa.


Body of pancreas:
It continues from the neck toward the left & upward. It is triangular in cross section, the apex is directed anteriorly (forming a ridge), while the base is directed posteriorly.

So body of pancreas will have 3 surfaces & 3 borders.

The borders of the body are : sup., ant. & inf. borders.
The sup. border is invaded by the splenic artery.
The ant. border: along which the transverse mesocolon is attached.
The inf. border: along this border lies the inf. pancreatic artery.
The surfaces of the body are : ant., post. & inf. surfaces.
The ant. surface is in continuity with neck of pancreas & it lies in the floor of the omental bursa & forms part of stomach bed.
The post. surface: behind this surface located (from right to left) aorta, left suprarenal gland & left kidney. In addition, the splenic vein passes along this surface.
The inf. surface is related to duodenojejunal flexure & coils of jejunum.
Tail of pancreas
It is blunted & directed upward and usually makes contact with spleen. Inferiorly it is in relation with the left colic flexure.
Arterial supply of duodenum & pancreas:
Is by : 1. Celiac trunk which gives gastroduodenal artery which will give:
Ant. sup. pancreaticoduodenal.
Post. sup. pancreaticoduodenal.
2. Sup. mesenteric artery which gives inf. pancreaticoduodenal artery which will divide into:
Ant. inf. pancreaticoduodenal.
Post. inf. pancreaticoduodenal.
The ant. sup. & ant. inf. pancreaticoduodenal arteries anastomosed with each other forming the ant. pancreaticoduodenal artery or arcade, anterior to the head of pancreas.
The post. sup. & post. inf. pancreaticoduodenal arteries anastomosed with each other forming the post. pancreaticoduodenal artery or arcade, behind the head of pancreas.
The ant. & post. pancreaticoduodenal arcades will supply the ant. & post. surfaces of head of pancreas & the 2nd , 3rd& 4th parts of duodenum.
Blood supply of the 1st part of duodenum:
*Supraduodenal artery * Retroduodenal artery
(these 2 branches are from gastroduodenal art.)
*Twigs from right gastric & right gastroepiploic arteries.
*Few branches from the highest parts of the arcades.


Blood supply of other parts of pancreas is from splenic artery, which gives:
Dorsal pancreatic artery: it gives Rt and Lt branches. The Lt is called inf. pancreatic artery.
Pancreaticomagna artery
Caudal pancreatic branches
*All pancreatic branches anastomose freely with each other.
Veins of duodenum & pancreas
The veins (which have the same names of arteries) will drain to sup. mesenteric, splenic and portal veins (portal circulation).
Lymphatic drainage
They follow the blood vessels.
Lymphatics of duodenum & pancreas pass to pancreaticoduodenal lymph nodes (lie along the arcades) and pancreaticolienal L.N (along the splenic vessels). Then from these nodes the lymphatics pass to celiac L.N , and to sup. mesenteric L.N (along the sup. mesenteric vessels).
Nerves of duodenum & pancreas:
From: - celiac plexus (sympathetic & parasympathetic), they reach duodenum & pancreas through hepatic, splenic plexuses
sup. Mesenteric plexus.