Abdomen: Viscera Flashcards
Innervation of peritoneum
Parietal: spinal somatic fibres: localised pain
Visceral: visceral afferents: referred pain
Greater sac and lesser sac (omental bursa)
Greater sac contains most of the abdomen
Lesser sac: posterior to stomach and liver

Omental epiploic foramen
Joins lesser sac to greater sac

Structures anterior to omental (epiploic) foramen
Hepatoduodenal ligament:
Portal vein
Hepatic artery proper
Bile duct

Structures posterior to epiploic foramen
inferior vena cava
Structures inferior to epiploic foraman
1st part of duodenum
Structures superior to epiploic foraman
caudate lobe of liver
Greater omentum
Greater curvature of stomach
Drapes down anterior to transverse colon, ileum and jejunum
Loops back up and joins transverse colon peritoneum

Lesser omentum
Lesser curvature of stomach to inferior liver

Mesenteries
The mesentery is formed by a double layered fold of peritoneum.
Although the mesentery is now thought to be a contiguous structure, subsections of the mesentery can be named according to the viscera it is associated with. Thus, names such as mesocolon, mesorectum, mesosigmoid all relate to different parts of the mesentery.
The ‘root’ of the mesentery is the point where the mesentery attaches to the posterior abdominal wall, and is therefore a ‘bare area’. Due to the range of abdominal organs the mesentery envelopes, the root is long, narrow and has an oblique orientation, from the** left side of the L2 vertebra to the right sacroiliac junction roughly.**
In the gastrointestinal tract, there are six flexures of note: duodenojejunal, ileocaecal, hepatic, splenic, and those between the descending and sigmoid colon and the sigmoid and rectum. These flexures are often used to mark the distinction between different portions of the mesentery:
Mesentery of the small intestine – connects the loops of jejunum and ileum to the posterior abdominal wall and is a mobile structure. (1)
Right mesocolon – flattened against the posterior abdominal wall (2)
Transverse mesocolon – a mobile structure (most mobile mesentery of large bowel) and lies between the colic flexures (3)
Left mesocolon – flattened against the posterior abdominal wall (4)
Mesosigmoid – has a medial portion which is flattened against the posterior abdominal wall, whereas the region of mesentery associated with the sigmoid colon itself is mobile. (5)
Mesorectum – assists in anchoring the rectum through the pelvis.(6)
Mesentery
The only double layered fold of peritoneum (4 layers)
connects jejunum and ileum to posterior wall
- at the jejunoduodenal junction just to the left of L2

Structures entering through the diaphragm
Vena cava + right phrenic T8
Oesophagus + vagus T10
Aorta + thoracic duct T12
Blood supply to abdominal oesophagus
Left gastric artery
Inferior phrenic artery
Different parts of stomach
Note: cardial notch: superior angle where oesophagus enters stomach
Angular incisure: bend on lesser curvature

Arterial supply of stomach
Left gastric
Short gastric
Gastro-epiploic arcade

Parts of duodenum
Superior
Descending
Inferior
Ascending

Duodenum intra or extraperitoneal
First part: extra peritoneal
Rest: intra peritoneal
Blood supply to duodenum
- Superior pancreaticoduodenal artery - arises from Gastro duodenal artery
- Inferior pancreaticoduodenal artery - arises from SMA
Their anastomosis represents the transition point from the foregut to the midgut at the dueodenal papilla

Difference in blood supply to ileum and jejunum
Supplied by SMA
Jejunum: longer vasa recta, smaller arcade
Ilieum: smaller vasa recta, more developed arcade

Source of bleeding from a posterior duodenal ulcer
Posterior wall
Gastroduodenal artery
The pancreas is the most intimate relation of the duodenal and patients will often complain of pain radiating to the back (dorsolumbar region) as a result of an ulcer or cancer irritating the pancreas
Different positions of appendix
Retrocaecal 74%
Pelvic 21%
Postileal
Subcaecal
Paracaecal
Preileal

Identification of appendix during surgery
Caecal taenia coli converge at base of appendix and form a longitudinal muscle cover over the appendix.
Blood supply to appendix
Appendicular artery (branch of ileo-colic artery)

Colon, intra or retroperitoneal
Appendix and caecum: intra
Ascending: retro
Transverse: intra
Descending: retro
Sigmoid: intra
Rectum: (distally) retro









