Anatomy of the abdominal viscera: Pancreas and spleen

Chapters:

Watch video only

Introduction0:00–0:18

Both the spleen and the pancreas are visceral organs in the foregut. Don’t get too excited though, that’s where their similarities end.
Other characteristics such as the shape and function within the body are quite different. So let’s break them down!Alright, let’s begin with the spleen, which has a few different important functions.

Spleen0:18–0:47

Prenatally, it functions as a hematopoietic organ, which means it makes fetal blood cells. After birth, the spleen is like a hub for lymphocyte proliferation, as well as a recycling center for damaged red blood cells and platelets, and a blood reservoir, from which backup blood can be pumped into circulation after significant hemorrhage.
For this reason, we can think of our spleen as our own personal blood bank. The spleen is oval in shape and is an intraperitoneal organ.

Position0:47–1:04

he spleen is an oval-shaped organ located in the left upper quadrant of the abdomen, and it is intraperitoneal. This means that the spleen is entirely enveloped in visceral peritoneum, except at the splenic hilum where the vasculature enters and exits the organ.

Borders1:04–1:28

The spleen has an anterior, superior and inferior border. The superior border of the spleen is easily recognizable due to its notched appearance.
The outer surface of the spleen can also be divided into two parts; the diaphragmatic surface which is in contact with the concavity of the diaphragm, and the visceral surface that is in contact with the surrounding abdominal viscera.

Anatomical relations1:28–2:15

Now, let’s break down the anatomical relationships of the spleen with its surrounding structures. The left portion of the diaphragm and the 9th to 11th ribs lie posterior to the spleen, with the diaphragm acting like a barrier between the spleen and the ribs.
The stomach lies anterior to the spleen and the two connect at the greater curvature of the stomach via the gastrosplenic ligament.
The spleen is lateral to the left kidney and the two are connected via the splenorenal ligament. The gastrosplenic and the splenorenal ligament contain splenic vessels within them and attach at the splenic hilum.The tail of the pancreas also often contacts the splenic hilum.
Lastly, the spleen lies just superior to the left colic flexure of the large intestine. Now let’s talk about blood supply, lymphatic drainage and innervation!

Arterial supply2:15–2:53

The spleen gets its blood supply via the splenic artery, which is a branch of the celiac trunk. After arising from the celiac trunk, the splenic artery takes a tortuous path posterior to the omental bursa, and runs along the superior border of the pancreas, ending at the splenic hilum.
The twisting and turning of the splenic artery gives it a worm-like appearance that is easily distinguishable. At the level of the hilum, the splenic artery then divides into several branches which enter the spleen to supply its different vascular segments.

Venous drainage2:53–3:09

Venous blood drains from the spleen via the splenic vein, which travels posterior to the pancreas, receiving the inferior mesenteric vein, and eventually uniting with the superior mesenteric vein to form the hepatic portal vein.

Lymphatic drainage3:09–3:24

Lymph from the spleen collects in the splenic lymph nodes located at the hilum, which eventually drain to the pancreaticosplenic and the celiac lymph nodes, using lymphatic vessels that run alongside the splenic vessels.Finally, splenic innervation is provided by nerve fibers of the celiac plexus, which course along the splenic artery.OK, now let’s take a quick break and try to recall the name and origin of the artery supplying the spleen.Alright, now let’s shift gears and talk about the pancreas.

Innervation3:24–3:33

Quiz3:33–3:49

Pancreas3:49–4:03

The pancreas is an elongated, accessory digestive organ that sits directly behind the stomach at the level of the transpyloric plane or the L1 and L2 vertebral bodies.

Position4:03–4:28

The pancreas is considered a retroperitoneal organ with the exception of its tail portion which is intraperitoneal. The pancreas is both an exocrine gland, secreting pancreatic juices into the duodenum to help with digestion; and an endocrine gland, secreting insulin and glucagon directly into the bloodstream, in order to regulate blood sugar metabolism.
You could say the pancreas is working two full time jobs! Anatomically, the pancreas is divided into five parts: the head, the uncinate process, the neck, the body, and the tail, and each of these parts have numerous relationships with surrounding structures.

Structure4:28–6:56

Let’s begin with the head of the pancreas, which sits within the curvature of the duodenum, just inferior to the level of the transpyloric plane and to the right of the superior mesenteric artery.A small part called the uncinate process projects medially from the inferior portion of the head, posterior to the SMA.
Next we have the neck, which lies anterior to the superior mesenteric vessels and posterior to the pylorus of the stomach, The body lies to the left of the superior mesenteric vessels, and posterior to the stomach continuing just above the transpyloric plane.
Finally, the tail of the pancreas is anterior to the left kidney and medial to the spleen. It’s closely related to the splenic hilum and is contained within the layers of the splenorenal ligament - alongside the splenic vessels - making the tail of the pancreas intraperitoneal.
The transverse mesocolon also attaches to the anterior surface of the pancreas.Now, the digestive juices produced by the pancreas are secreted into a large duct known as the main pancreatic duct, which eventually leads to the duodenum.
The main pancreatic duct starts in the tail and runs towards the head, where it unites with the bile duct coming from the liver, to form the hepatopancreatic ampulla, also known as the ampulla of Vater.
The hepatopancreatic ampulla enters into the descending part of the duodenum through an opening known as the major duodenal papilla.
This papilla is surrounded by a ring of smooth muscle called the sphincter of Oddi, which acts as a door that opens and closes to control the flow of the pancreatic juice and bile into the duodenal lumen.
Sometimes an anatomical variation occurs where the main pancreatic duct gives a branch known as the accessory pancreatic duct, which opens into the duodenum at a separate location known as the minor duodenal papilla.
Let’s take another break, and see if you can label the parts of the pancreas “A” through “E”. Now let’s talk about blood supply, lymphatic drainage and innervation of the pancreas!

Quiz6:56–7:07

Most of the arterial supply is provided by pancreatic branches of the splenic artery. A smaller portion of its blood supply, especially to the head and the uncinate process, is supplied by the anterior and posterior superior pancreaticoduodenal arteries which are branches of the gastroduodenal artery; and also by the anterior and posterior inferior pancreaticoduodenal arteries, which are branches of the superior mesenteric artery.

Arterial supply7:07–7:37

Venous blood leaves the pancreas through the pancreatic veins, which in turn empty into the superior mesenteric and splenic veins.
Lymph collects in the pancreaticosplenic lymph nodes lying along the splenic artery, in addition to the pyloric lymph nodes.

Venous drainage7:37–7:48

Lymphatic drainage7:48–7:59

Lastly, sympathetic innervation to the pancreas is provided by the greater and lesser splanchnic nerves, while parasympathetic innervation is from the vagus nerves.
Both the sympathetic and parasympathetic fibers pass through the celiac and superior mesenteric plexuses before reaching the pancreas.Alright, as a quick recap!

Innervation7:59–8:19

The spleen is an intraperitoneal organ located in the left upper quadrant of the abdomen. The spleen is mainly responsible for red blood cell and platelet filtration, and it also plays a major role in immune system function.

Review8:19–9:14

Its arterial supply is from the splenic artery while venous blood drains into the splenic vein. The pancreas is a mainly retroperitoneal organ that sits posterior to the stomach.
It is anatomically divided into five parts; the head, the uncinate process, the neck, the body, and the tail. The pancreas has a dual role as an endocrine gland regulating blood-sugar metabolism, and an exocrine gland secreting the pancreatic juice into the duodenum.
These juices channel through the main pancreatic duct joining the bile duct to form the hepatopancreatic ampulla which secretes into the duodenum through the major duodenal papilla.
Blood supply to the pancreas is provided by the pancreatic branches of the splenic artery and the superior and
Anatomy of the abdominal viscera: Pancreas and spleen: Video | Osmosis