Anatomy - Peritoneum Flashcards
What is the peritoneum?
- A single continuous membrane lining the abdominal membrane
- Made of simple squamous epithelium (mesothelium)
What is the difference between the abdominal and peritoneal cavity?
- The abdominal cavity is everything inside the abdominal wall
- The peritoneal cavity is inside the peritoneum. It is a potential space between the visceral and parietal layers of the peritoneum
What are mesentries?
Modified peritoneal reflections, from which abdominal organs are suspended from the abdominal wall.
What is the purpose of mesentries?
Acts as a condiut for vessels, nerves and lymphatics
What is the difference between intraperitoneal and retroperitoneal cavities?
- Intraperitoneal are structures suspended form the abdominal wall by mesentries
- Retreoperitoneal structures lie between the parietal peritoneum and abdominal wall
List the retroperitoneal structures.
- Kidneys and ureters
- Supradrenal glands
- Aorta/IVC
- Nerves (lumbar plexus and sympathetic trunk)
- Oesophagus
- Rectum
Secondary:
- Duodenum (except the start)
- Pancreas
- Colon (ascending and descending)
What is the difference between primary and secondarily retroperitoneal organs?
Secondary retroperitoneal organs origionally had a mesentry, then became secondarily retroperitoneal when the mesentry fused with the body wall
Where is the foregut?
Distal 3rd of oesophagus to 2nd part of the duodenum at the entrance of the bile duct
Where is the midgut?
2nd part of duodenum to two thirds along the transverse colon
Where is the hindgut?
Distal 3rd of the transverse colon to the rectum
Where are the dorsal and ventral mesentry?
- Whole gut tube suspended from the dorsal mesentry, which attaches to the greater curve of the stomach
- Foregut has a ventral mesentry as well (encloses the liver and pancreas), which attaches to the lesser curve of the stomach
What are the subdivisions of the gut?
- Lesser sac (ommental bursa), which forms when the liver rotates while growing, forming a sac inbetween the liver and the stomach posterior. Ventral foregut mesentry
- Greater sac/omentum covers the abdomen like a sheet. This is the dorsal foregut mesentry
What is the epiploic foramen?
Where the ommental bursa is continuous with the greater sac.
What structures are on the right free edge of the ommental bursa?
- Portal vein
- Hepatic artery
- Bile duct
What are the peritoneal compartments?
- Supracolic compartment (above the mesentry of the transverse colon)
- Infracolic compartment (below the mesentry of the transverse colon)
- Paracolic gutter (right/left of the abdomen)
What is the falciform ligament?
Attaches the liver to the diaphragm
Describe the direction of peritoneal fluid and inflammatory exudate.
- Peritoneal fluid goes towards the diaphragm where it is reabsorbed
- Inflammatory exudate flows downwards, towards the pelvis
Compare the functions between the outer muscularis layer of the abdomen and the inner mucosa muscularis
- Muscularis layer causes peristalisis and segmentation
- Mucosa muscularis causes small movements to prevent food getting stuck to serosa
What is the first part of the duodenum?
Duodenal cap
Name the entrance for the common bile duct in the duodenum, and describe its location
- Major duodenal papilla
- In the second part of the duodenum
How can the jejunum and illeum be distinguished?
- Jejunum has less prominant arterial arcades, and longer vasa recta
- Illeum has more prominant arterial arcades and short vasa rects
- Jejunum has a larger diameter
List the parts of the large intestine
- Caecum
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
How can the large intestine and small intestine be distinguished?
- Large intestine has fatty tags, called appendices epiploicae
- Large intestine has longitudinal muscle in its walls segregated into three bands, taeniae coli
- LI has larger diameter
What artery supplies the foregut, liver, pancreas and spleen?
Coeliac trunk
Which artery supplies the midgut?
Superior mesenteric artery
Which artery supplies the hind gut?
Inferior mesenteric artery
Where do the arteries supplying the gut arise from?
Anterior of the aorta - they are unpaired
What are the branches of the celiac trunk, and where do they arise?
Upon arising from the abdominal aorta immediately below the diaphragm, the coeliac artery splits into the:
- Left gastric artery
- Splenic artery
- Common hepatic arteries
Describe the pathway of the left gastric artery
- Esophageal branches supply the oesophagus
- Descends along the lesser curvature of the stomach in the lesser omentum, supplying the stomach and anastamosing with the right gastric artery
Describe the pathway of the splenic artery
- Moves along the left, the superior border of the pancreas
- Travels in the splenorenal ligament
- Branches enter the right hilum of the spleen
- Short gastric arteries supply the fundus of the stomach
- Left gastroomental artery runs along the greater curvature of the stomach, and anastamoses with the right gastro-omental artery
Describe the pathway of the common hepatic artery
- Hepatic artery proper (forms right and left hepatic arteries)
- Gastroduodenal artery (right gastro-omental artery and anterior superior pancreaticoduodenal artery)
List the branches of the superior mesenteric artery
- Inferior pancreaticoduodenal artery
- Jejunal and ileal arteries
- Middle colic artery
- Right colic artery
- Ileocolic artery
List the branches of the inferior mesenteric artery
- Left colic artery
- Sigmoid arteries
- Superior rectal artery
List the veins draining the abdomen
- All the veins end up in the portal vein which goes to the liver
- From superior mesenteric vein, inferior mesenteric vein and splenic vein
- First inferior mesenteric joins the splenic, then this vein joins the superior mesenteric
What are portal systemic anastamoses?
Where the veins draining to the portal vein and the IVC communicate
Describe the main lymphatics in the gut
- Follows the arterial supply
- Lymph all drains into cisterna chyli
- Involves the coelic nodes, superior mesenteric nodes, and inferior mesenteric nodes
Describe the innervation of the gut
- Viscera supplied by the autonomic nervous system
- PNS controls regulate reflex gut function (vagus nerve and pelvic splancnic nerves, S2-4)
- SNS mediates pain (thoracic splancnic T5-12 and lumbar splanchnic L1 and 2)
What nerves does the thoracic splanchnic nerve give rise to?
- Greater splanchnic nerve (T5-9)
- Lesser splanchnic nerve (T10-11)
- Least splanchnic nerve (T12)
What are the effects of parasympathetic efferents on the gut?
- Increased peristalsis
- Relax sphincters
- Increase secretion
What are the effects of the sympathetic efferents on the gut?
- Decreased peristalsis
- Constrict sphincters
- Decrease blood flow and secretions
Describe the blood supply of the stomach
- Greater curvature supplied by left and right gastroepliploic arteries
- Fundus is supplied by the short gastric artery
- Lesser curvature is supplied by the right and left gastric arteries
- The cardiac region is supplied by the left gastric
Describe the blood supply of the pancreas
- Head supplied by superior pancreaticoduodenal and superior mesenteric arteries
- Tail, body and neck supplied by pancreatic branches of the splenic artery
