Foregut Flashcards
Stomach vasculature, innervation and lymphatics
The arterial supply to the stomach comes from the celiac trunk and its branches.
* Right gastric – branch of the common hepatic artery, which arises from the coeliac trunk.
* Left gastric – arises directly from the coeliac trunk.
* Right gastro-omental – terminal branch of the gastroduodenal artery, which arises from the common hepatic artery.
* Left gastro-omental – branch of the splenic artery, which arises from the coeliac trunk.
The veins of the stomach run parallel to the arteries. The right and left gastric veins drain into the hepatic portal vein. The short gastric vein, left and right gastro-omental veins ultimately drain into the superior mesenteric vein
Innervation-
* Parasympathetic nerve supply arises from the anterior and posterior vagal trunks, derived from the vagus nerve.
* Sympathetic nerve supply arises from the T6-T9 spinal cord segments and passes to the coeliac plexus via the greater splanchnic nerve. It also carries some pain transmitting fibres.
Lymphatics-
The gastric lymphatic vessels travel with the arteries along the greater and lesser curvatures of the stomach. Lymph fluid drains into the gastric and gastro-omental lymph nodes found at the curvatures. Efferent lymphatic vessels from these nodes connect to the coeliac lymph nodes, located on the posterior abdominal wall
Parietal peritoneum lines…
lines the abdominal cavity
Visceral peritoneum lines…
lines the abdominal viscera (internal organs)
Greater omentum consists of…
four layers of visceral peritoneum- two double layers on top of each other
Lesser omentum consists of…
One double layer of visceral peritoneum
Mesentery consists of…
double layer of visceral peritoneum that envelopes the intestines
Intraperitoneal means…
enveloped on all surfaces by visceral peritoneum
Retroperitoneal means and includes…
only one surface is covered by either visceral or parietal peritoneum:
S- suprarenal glands (adrenal)
A- aorta
D- duodenum (except proximal 2cm)
P- pancreas (except tail)
U- ureters
C- colon (ascending and descending)
K- kidneys
E- oesophagus
R- rectum
Duodenum vasculature, innervation and lymphatics
• Proximal to the major duodenal papilla – supplied by the gastroduodenal artery (branch of the common hepatic artery from the coeliac trunk).
• Distal to the major duodenal papilla – supplied by the inferior pancreaticoduodenal artery (branch of superior mesenteric artery).
This transition is important – it marks the change from the embryological foregut to midgut. The veins of the duodenum follow the major arteries and drain into the hepatic portal vein.
Lymphatic drainage is to the pancreatoduodenal and superior mesenteric nodes
Innervation is greater splanchnic nerves via celiac plexus (sympathetic), vagus nerve (CN X) via anterior and posterior vagal trunks (parasympathetic)
Oesophagus neurovascular supply and lymphatics
Thoracic
The thoracic part of the oesophagus receives its arterial supply from the branches of the thoracic aorta and the inferior thyroid artery (a branch of the thyrocervical trunk).
Venous drainage into the systemic circulation occurs via branches of the azygous veins and the inferior thyroid vein.
Abdominal
The abdominal oesophagus is supplied by the left gastric artery (a branch of the coeliac trunk) and left inferior phrenic artery. This part of the oesophagus has a mixed venous drainage via two routes:
• To the portal circulation via left gastric vein
• To the systemic circulation via the azygous vein.
These two routes form a porto-systemic anastomosis, a connection between the portal and systemic venous systems.
Innervation-
The oesophagus is innervated by the oesophageal plexus, which is formed by a combination of the parasympathetic vagal trunks and sympathetic fibres from the cervical and thoracic sympathetic trunks.
Two different types of nerve fibre run in the vagal trunks. The upper oesophageal sphincter and upper striated muscle is supplied by fibres originating from the nucleus ambiguous. Fibres supplying the lower oesophageal sphincter and smooth muscle of the lower oesophagus arise from the dorsal motor nucleus.
Lymphatics-
• Superior third – deep cervical lymph nodes.
• Middle third – superior and posterior mediastinal nodes.
Lower third – left gastric and celiac nodes.
Spleen neurovasculature and lymphatics
It receives most of its arterial supply from the splenic artery.
Venous drainage occurs through the splenic vein. It combines with the superior mesenteric vein to form the hepatic portal vein.
The nerve supply to the spleen is from the coeliac plexus.
The lymphatic vessels of the spleen follow the splenic vessels mentioned above and drain into the pancreaticosplenic lymph nodes, and ultimately the coeliac nodes
Liver neurovasculature and lymphatics
• Hepatic artery proper (25%) – supplies the non-parenchymal structures of the liver with arterial blood. It is derived from the coeliac trunk.
• Hepatic portal vein (75%) – supplies the liver with partially deoxygenated blood, carrying nutrients absorbed from the small intestine. This is the dominant blood supply to the liver parenchyma, and allows the liver to perform its gut-related functions, such as detoxification.
Venous drainage of the liver is achieved through hepatic veins. The central veins of the hepatic lobule form collecting veins which then combine to form multiple hepatic veins. These hepatic veins then open into the inferior vena cava.
The parenchyma of the liver is innervated by the hepatic plexus, which contains sympathetic (coeliac plexus) and parasympathetic (vagus nerve) nerve fibres. These fibres enter the liver at the porta hepatis and follow the course of branches of the hepatic artery and portal vein.
Glisson’s capsule, the fibrous covering of the liver, is innervated by branches of the lower intercostal nerves. Distension of the capsule results in a sharp, well localised pain.
The lymphatic vessels of the anterior aspect of the liver drain into hepatic lymph nodes. These lie along the hepatic vessels and ducts in the lesser omentum, and empty in the colic lymph nodes which in turn, drain into the cisterna chyli.
Lymphatics from the posterior aspect of the liver drain into phrenic and posterior mediastinal nodes, which join the right lymphatic and thoracic ducts.
