Stomach and spleen Flashcards
What organs make up the foregut?
-From distal oesophagus to superior half of duodenum
-Including stomach, pancreas, spleen, liver, gallbladder
What organs make up midgut?
-From interior half of duodenum to proximal 2/3 of transverse colon
-Including jejenum, ileum, caecum, appendix, ascending colon
What organs make up the hindgut?
-From distal 1/3 of transverse colon to superior half of rectum
-Including descending and sigmoid colon
Surface projection of stomach
-Stomach is intraperitoneal and located in left upper quadrant, epigastric, umbilical and left hypochondrium regions (in supine positions)
-Size, shape and position of stomach can vary based on diaphragm, stomach’s content, and person’s position
-Transpyloric line is important landmark; pylorus hardly moves because connected to duodenum which is mostly retroperitoneal
Surface projection of spleen
-Left upper quadrant or left hypochondrium region
-Posteriorly, associated with left 9th to 11th ribs
-Long axis parallel to left 10th rib when viewed laterally
Stomach and spleen in situ
Stomach description
-Expanded part of GI tract between oesophagus and duodenum
-Specialised for accumulation of ingested food which is chemically and mechanically prepared for digestion/passage into the duodenum
-Enzyme and gastric juice help turn food into chyme
4 parts of stomach
Interior of stomach
-Covered by continuous mucous layer that protects its surface from gastric acid and
-Gastric mucosa forms prominent gastric folds (rugae) to increase its surface area
-Gastric folds diminish as surface fills
Relations of stomach
-2 layers of the lesser omentum extend around stomach and continue as the greater omentum at the greater curvature
-Anteriorly, stomach is related to left lobe of liver and anterior abdominal wall
-Posteriorly, to omental bursa and pancreas
-Inferiorly, to transverse colon
Spleen description
-Anatomically, an abdominal organ, but functionally a lymphatic organ
-Site of lymphocyte proliferation and immune surveillance/response
-Prenatally, spleen is haematopoietic (blood-forming), after birth it removes/destroys aging red blood cells/platelets and stores newly generated ones
-Anterior and superior borders are sharp and notched, posterior and inferior borders are rounded
Relations of the spleen
-Connects to greater curvature of stomach by gastrosplenic ligament
-Connects to left kidney by splenorenal ligament
-These ligaments contain splenic vessels and attach to hilum of spleen
-Anteromedially, spleen is related to stomach
-Posterolaterally, left part of diaphragm and left ribs 9-11
-Inferiorly, to the left colic flexure (junction between transverse and descsending colon)
-Posteromedially, to the left kidney
How does the abdominal aorta branch?
-Coeliac trunk which is at level of aortic hiatus (T12)
-Coeliac trunk gives rise to left gastric, splenic and common hepatic artery
Arterial supply of stomach
-Most blood supplied by anastomoses formed along the lesser curvature by right and left gastric arteries, and greater curvature by the right and left gastro-omental arteries
-Fundus and upper body receive blood from short and posterior gastric arteries
What is the only foregut structure that receives blood supply from all 3 branches of the coeliac trunk?
Stomach
Venous drainage of stomach (overview)
-Veins of stomach run parallel to arteries
-Venous blood of gastrointestinal organs either drains directly into hepatic portal vein or by splenic, superior/inferior mesenteric veins to reach hepatic portal vein
Venous drainage of stomach (detailed)
-Right and left gastric veins drain into hepatic portal veins
-Short gastric veins and left gastro-omental veins drain into splenic vein, which joins the superior mesenteric vein (SMV) to form hepatic portal vein
-Right gastro-omental vein empties into the SMV
Blood supply of spleen
-Arterial blood supply of spleen is from splenic artery
-Follows tortuous course along superior border of pancreas
-Venous blood flow of spleen via splenic vein
-Joined by inferior mesenteric vein (IMV) and runs posterior to pancreas
Nerve supply of stomach and spleen
-Parasympathetic nerve supply of stomach is from anterior/posterior vagal trunks and their branches, which enter abdomen through the oesophageal hiatus
-Preganglionic sympathetic nerve fibres of the stomach from T5-T9/10 pass to coeliac ganglion through greater splanchnic nerve
-They synapse, become post ganglionic and continue to stomach
-Spleen receives its sympathetic supply from coeliac ganglion the same way as stomach. It receives its parasympathetic supply from the vagal trunks. More specifically, these sympathetic and parasympathetic fibres to the spleen run along the splenic artery as the splenic nerves
Rupture of the spleen
-Spleen is well protected by ribs, but blunt trauma to the left side of abdomen can fracture these ribs and rupture the spleen
-As a blood reservoir, rupture of the spleen will result in profuse bleeding (intraperitoneal haemorrhage)
Splenomegaly
-Spleen not normally palpable due to ribcage
-However when spleen enlarges due to haematopoietic disorders, inferior edge can be detected below the left costal margin at the end of inspiration.
-As a result, the left colic flexure and transverse colon are displaced inferiorly and the descending colon medially in extreme cases
