The superior mesenteric artery (SMA) is the second of the three major anterior branches of the abdominal aorta, the other two being the coeliac trunk and inferior mesenteric artery. It arises anteriorly from the abdominal aorta at the level of the L1 vertebrae, immediately inferior to the origin of the coeliac trunk.
The SMA then descends down the posterior aspect of the abdomen, and has several important anatomical relations. The anterior side of the SMA is related to the pyloric part of the stomach, splenic vein and neck of the pancreas. On the posterior side, it is related to the left renal vein, uncinate process of the pancreas and inferior part of the duodenum. The uncinate process is the only part of the pancreas that wraps around the back of the SMA.
The SMA then gives rise to various branches that supply the small intestines, cecum, ascending and part of the transverse colon. These branches are summarised below.
The inferior pancreaticoduodenal artery is the first branch of the SMA. It forms both anterior and posterior vessels which anastomose with branches of the superior pancreaticoduodenal artery, a branch derived from the coeliac trunk. This network of vessels supplies the inferior region of the head of the pancreas, the uncinate process, and the duodenum.
The SMA gives rise to numerous arteries that supply the jejunum and ileum. The arteries pass between the layers of the mesentery and form anastomotic arcades, from which smaller, straight arteries (known as “vasa recta”) arise to supply the organs. The jejunal blood supply is characterised by a smaller number of arterial arcades, but longer vasa recta. This differs from the ileal blood supply, which is marked by more arterial arcades with shorter vasa recta.
The right and middle colic arteries arise from the right side of the SMA in order to supply the colon. The middle colic artery supplies the transverse colon, while the right colic artery supplies the ascending colon.
The ileocolic artery is the final major branch of the SMA. It passes inferiorly and to the right, giving rise to branches to the ascending colon, appendix, cecum, and ileum. In cases of appendectomy, the appendicular artery is usually ligated.
Occlusion of the SMA can restrict arterial blood flow to the midgut, resulting in intestinal ischaemia. This is more common in the elderly, and usually presents with abdominal pain. The most useful investigation in such cases is a CT scan of the abdomen. Treatment of occlusion of the SMA is usually surgical.
In conclusion, the superior mesenteric artery is a critical artery that arises from the abdominal aorta and supplies arterial blood to the organs of the midgut. It has several important anatomical relations, and gives rise to various branches that supply the small intestines, cecum, ascending and part of the transverse colon. Its occlusion has serious implications on the health of the patient, and in such cases the appropriate treatment is surgical.
The Superior Mesenteric Artery (SMA) is an artery located in the abdominal cavity that is a major branch of the abdominal aorta. In the anatomical position, the artery runs downwards to the small intestine, supplying branches to the inferior region of the head of the pancreas, the uncinate process, and the duodenum. In addition, the SMA supplies numerous arteries to the jejunum and ileum that form anastomotic arcades, which are subsequently from which smaller, straight arteries (known as the vasa recta) arise to supply the organs. These jejunal and ileal arteries are characterised by a smaller number of arterial arcades, but longer vasa recta for the jejunum and more arterial arcades with shorter vasa recta for the ileum. Additionally, the SMA gives rise to the right and middle colic arteries to supply the colon; the middle colic artery supplies the transverse colon while the right colic artery supplies the ascending colon. Lastly, the ileocolic artery is the final major branch of the superior mesenteric artery that passes inferiorly and to the right, giving rise to branches to the ascending colon, appendix, cecum, and ileum.
Occlusion of the Superior Mesenteric Artery (SMA) is a serious medical condition that can arise from a number of causes, including thrombosis, embolism, abdominal aortic aneurysm, and aortic dissection. When left untreated, this condition restricts blood flow to the midgut, resulting in intestinal ischaemia. It is more common in the elderly, and most usually presents with abdominal pain. The most useful investigation in this scenario is a CT scan of the abdomen, while the most common treatment for SMA occlusion is surgery.
In order to diagnose and treat SMA occlusion, it is of utmost importance to be aware of the anatomy of the SMA and the vital roles it plays in the body. The SMA is a major branch of the abdominal aorta that runs downwards to the small intestine, supplying branches to the inferior region of the head of the pancreas, the uncinate process, the duodenum, as well as numerous arteries to the jejunum and ileum that form anastomotic arcades – from which smaller, straight arteries (known as the vasa recta) arise to supply the organs. These arcades are characterised by a smaller number of arterial arcades, but longer vasa recta for the jejunum and more arterial arcades with shorter vasa recta for the ileum. Additionally, the SMA gives rise to the right and middle colic arteries to supply the colon; the middle colic artery supplies the transverse colon while the right colic artery supplies the ascending colon. Lastly, the ileocolic artery is the final major branch of the superior mesenteric artery that passes inferiorly and to the right, giving rise to branches to the ascending colon, appendix, cecum, and ileum.
There are several risk factors that can increase a person's likelihood of developing SMA occlusion. These include:
The most common symptom of SMA occlusion is abdominal pain, which is typically located in the lower right quadrant of the abdomen. Other signs and symptoms may include:
If SMA occlusion is suspected, a CT scan of the abdomen is typically ordered to confirm the diagnosis. Additionally, an ultrasound or MRI may be ordered to assess the extent of the occlusion.
The treatment of SMA occlusion typically involves surgery to remove any blockages or clots that have formed along the artery and to reroute blood flow. In some cases, however, medications may be prescribed to reduce cholesterol levels or to thin the blood in order to prevent further clotting. In severe cases, a bypass may be performed to completely reroute the blood supply to the affected area. Additionally, lifestyle changes and medical management may be recommended to reduce the risk of SMA occlusion in the future.
The Superior Mesenteric Artery (SMA) is an important artery in the abdominal cavity that is a major branch of the abdominal aorta. Occlusion of the SMA can lead to a variety of medical complications, including thrombosis, embolism, abdominal aortic aneurysm, aortic dissection, and intestinal ischaemia. Treatment typically involves surgery to remove the blockages and to reroute blood flow, and lifestyle changes and medical management may be recommended to reduce the risk of SMA occlusion in the future.
