Anatomy of the Abdomen and Pelvis Flashcards
Explain why parietal pain is well localised whereas visceral pain is poorly localised
The parietal peritoneum is innervated by the same somatic nerves that innervate the abdominal skin covering its surface. Therefore pain will be well localised to this overlying area.
Visceral peritoneum is supplied by the same nerve fibres and spinal nerve roots as the organs that it covers. Therefore, visceral pain will be referred to the dermatome supplied by its spinal nerve root.
What are the two layer of peritoneum ?
Parietal peritoneum- lines the internal surface of the abdominopelvic wall
Visceral peritoneum- invaginates cover the majority of the abdominal organs
They are continuous with each other
List the retroperitoneal organs of the GI tract
Suprarenal glands
Aorta/IVC
Duodenum (D2 & D3)
Pancreas (except the tail) Ureters Colon (ascending and descending only) Kidneys Eosophagus Rectum (front and sides of top 1/3 and only front of middle 1/3)
What is the function of mesentery?
Attaches intraperitoneal organs to the abdominal wall
What is the significance of the epiploic foramen?
Connects the greater sac to the lesser sac
What is the mesocolon?
Mesentery which attaches the transverse colon to the posterior abdominal wall.
Where does the ‘apron’ hang?
After attaching to the lesser curvature of the stomach, the omentum splits in two to enclose the stomach and reforms on the greater curvature where it hangs like an apron. The two laters fold on themselves and travel upwards to enclose the transverse colon. Past the transverse colon the momentum is referred to as the ‘mesocolon’
Give examples of intraperitoneal organs
Stomach, Small intestine, Transverse colon, Sigmoid colon
What structures are found in the free border of the lesser omentum?
Hepatic artery (very small), Hepatic portal vein and common bile duct
What ligament is compressed when performing the ‘Pringle Manoeuvre”? Why would this manoeuvre be performed?
Hepatoduodenal ligament (attached from porta hepatis to duodenum). Compressed on ligament with a clamp stops the venous and arterial supply to the liver, minimising further haemorrhage
Following a pringle manoeuvre, if blood continues to accumulate in the hepatic-renal recess, what injury should be suspected?
A liver laceration
Blood can’t get in because it’s been clamped so the increasing haemorrhage must mean blood is getting out. The blood must be leaking from the veins in the liver i.e. hepatics veins.
What is the attachment of the mesentery to the posterior abdominal wall?
The attachment of the mesentery to the posterior abdominal wall is called the root of the mesentery. After enclosing the transverse colon the mesentery ‘fans out’ with the top part lining the diaphragm and the bottom part lining the posterior abdominal wall.
What are the two peritoneal attachments of the spleen? What is contained within these two ligaments
Splenorenal ligament
Gastrosplenic ligament
The splenorenal ligament contains the splenic artery and vein and the tail of the pancreas (the only intra peritoneal portion of the pancreas)
Why is the spleen prone to injury in deceleration accidents?
Relatively mobile peritoneal connections therefore the spleen can accelerate with the body and then experience the full shearing forces associated with deceleration during a crash. Can cause tearing of vessels which can cause life threatening haemorrhage.
Why is acute pancreatitis associated with splenic injury?
Contents from ruptured splenic vessels can irritate the tail of the pancreas which lies in the splenorenal ligament causing acute inflammation
List 5 reasons why a trauma patient may require a laparotomy
1) Penetrating trauma w/hypotension e.g. stab wound
2) Gunshot wounds traversing the abdominal cavity
3) Free air or retroperitoneal air or if the diaphragm has ruptured
4) Peritonitis
5) CT showing perforation
6) Evisceration
What is the seatbelt sign and what does it suggest?
Transverse linear ecchymosis often seen in RTA and associated with wearing a lap belt. If seen, indicative of retroperitoneal and organ injury
What type of vertebral fracture is associated with severe truncal flexion and lap belts?
Transverse lumbar fracture ‘chance fracture’
What is a ‘bucket handle injury’ of the small intestines? What is the most likely injury
Small intestine separates from the mesentery and can become ischaemic and necrotic. Most commonly occur after blunt abdominal trauma and requires extremely high force resulting in rapid deceleration e.g. motorcycle crash
In trauma, what can FAST scanning screen for?
Intra-Abdominal free fluid (blood in the peritoneal space “haemoperitoneum”
Cardiac tamponade
Which areas are typically imaged in a trauma FAST scan?
1) Pericardial sac- cardiac tamponade
2) Hepatorenal recess- liver lacerations
3) Splenorenal fossa
3) Pouch of douglas- between bladder and return
Which parts of the diaphragm is most commonly injured? Why?
Left side of the diaphragm as the liver acts as a buffer partially preventing inferior organs from penetrating through the diaphragm
What two arteries supply most of the diaphragm?
Inferior phrenic arteries
What are the crura of the diaphragm?
Right and Left crus are the parts of the diaphragm that arise from the vertebrae . They are tendinous in structure
Which organs are most commonly injured in blunt direct blow trauma?
Spleen, liver, small bowel
Which organs are most commonly injured in blunt decelerating trauma?
Intraperitoneal organs such as liver and spleen
Which organs are most commonly injured in penetrating trauma?
Liver, small bowel, diaphragm
Are the injury patterns in hollow organs the same as in solid organs
Hollow organs aren’t as vascular as solid organs so minimal haemorrhage. Hollow organs might spill their contents which could lead to peritonitis
Where is the foregut? What artery supplies it?
The foregut extends from the oesophagus to the second part of the duodenum where the bile duct enters. It is supplied by the coeliac trunk
Describe the blood supply to the stomach
The left gastric artery (direct branch of the coeliac trunk) anastomoses with the right gastric artery (a branch of the common hepatic artery) to supply the lesser curvature of the stomach. The greater curvature of the stomach is supplied by the left and right gastroepiploic arteries which anastomose along the curvature.
Rich arterial anastomoses are present along the greater and lesser curvatures.
What forms the right gastroepiploic artery?
Branch of the gastroduodenal
What forms the left gastroepiploic artery?
Branch of the splenic
What are the three branches of the coeliac trunk?
Splenic artery, Left gastric artery, Common hepatic artery
Describe the blood supply to the duodenum
Gastroduodenal artery (branch of the common hepatic artery) branches to form the superior pancreaticoduodenal artery. The artery anastomoses with the inferior pancreaticoduodenal (SMA) artery along the curved border of the duodenum to supply it and the HEAD OF THE PANCREAS.
What is the inferior pancreaticoduodenal artery a branch of?
Superior mesenteric artery
Where is the midgut? What artery supplies the midgut?
Duodenum (at the point of bile duct entry) to 2/3rds along the transverse colon. The midgut is supplied by the superior mesenteric artery
Describe the blood supply of the jejunum and ileum
Branches of the superior mesenteric artery which runs in the mesentery attaching the jejunum and ileum to the posterior abdominal wall. Arterial arcades form and terminal arteries called ‘vasa rectae’ exit these arcades to supply the J&I. The jejunum has few arcades and long vasa rectae. The ileum has more arcades and shorter vasa rectae.
Which parts of the colon are retroperitoneal?
Ascending and descending colon
How can the large bowel be distinguished from the small bowel?
Taenia coli- longitudinal bands of muscle
Haustrations- sacculations caused by the pull of the taenia coli
Appendices epiploicae- fat lobules covering peritoneum
Describe the blood supply of the colon in the mid-gut
The midgut colon (up to 2/3rd transverse colon) is supplied by branches of the superior mesenteric artery. These branches include the ileocolic, right colic and middle colic. The ileocolic also gives off the anterior and posterior caecal arteries and the appendicular artery