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
What is the hindgut? What is its blood supply?
2/3rd along transverse colon to rectum and supplied by inferior mesenteric artery
Describe the blood supply of the hindgut
Inferior mesenteric artery gives off the left colic (1/3 TC + descending colon), sigmoidal artery and then descends into the pelvis and continues as the superior rectal artery.
What is the relevance of the marginal artery of Drummond?
Colic arteries form a number of anastomoses which forms the marginal artery of the drummond. This artery runs from the ileocolic to the colorectal junction and can supply the large bowel if colic supply is restricted
Where in the large bowel is at greatest risk of ischaemia?
The splenic flexure ‘the watershed area’ because this is where the left colic and marginal artery meet. Both arteries will have already supplied other bowel regions with oxygen so their remaining levels will be low/ Hence obstruction of one artery can lead to ischaemic colitis
What is the blood supply to the rectum?
Superior and inferior rectal arteries
The —– drains 75% of blood into the liver.
Hepatic portal vein
The hepatic portal vein is formed by which vessels?
SPLENIC vein anastomoses with the INFERIOR MESENTERIC VEIN which drains the hindgut which joins the SUPERIOR MESENTERIC VEIN forming the HEPATIC PORTAL VEIN
The hepatic artery proper is formed by which vessel? What arterial branches does it give off?
Common hepatic artery
Cystic artery
Right gastric artery
Which vessels do you think are more prone to a shearing injury i.e. deceleration?
SMA and SMV- they are suspended in the mesentery
Where do the right and left gonadal veins drain into ?
Right- drains directly into the IVC
Left- drains into the left renal vein (explains why renal masses can lead to varicocele)
Which three arteries supply the adrenal glands? Where do these arteries branch from?
Superior suprarenal arteries- Inferior phrenic artery
Middle suprarenal arteries- Abdominal aorta
Inferior suprarenal arteries- Renal artery
What vertebral level does the coeliac trunk come off the abd. aorta?
T12
What vertebral level does the SMA come off the abd. aorta?
L1
What vertebral level does the IMA come off the abd. aorta?
L3
What vertebral level does the aorta bifurcate?
L4
What does REBOA stand for, how does it work and and when is it used in the pre-hospital setting?
Resuscitative endovascular balloon occlusion of the aorta. Provides temporary occlusion of the aorta, reducing bleeding distally and increases perfusion of tissues proximal to balloon e.g. brain, heart, kidneys. Used in severe haemorrhage from pelvic and long bone fractures in the legs
What are the levels used in REBOA? Up to what level is currently used prehospitally in the UK?
Zone 1-3. Zone 3 is currently used in the UK and is the aorta extending from the most caudal renal artery to the bifurcation. A balloon catheter is introduced into the femoral artery using the seldinger technique. The balloon is inflated at the aortic bifurcation point (roughly just above umbilicus)
What are the main complications of REBOA?
- Local infection- PSOAS abscess
- Incorrectly puncturing femoral vein- retroperitoneal hematoma (RIF pain)
- Aortic tears/rupture due to balloon inflation
- Ischaemic limbs
- Reperfusion injury
- Thromboembolism
What are the three REBOA zones?
Zone I of the aorta extends from the origin of the left subclavian artery to the coeliac artery
Zone II extends from the coeliac artery to the most caudal renal artery
Zone III extends distally from the most caudal renal artery to the aortic bifurcation
Which ribs do the kidneys lie anterior to?
Right - T11
Left- T11 + 12
Which muscles and nerves are the kidneys related to posteriorly ?
Muscles- psoas major, quadratus lumborum & transversus abdominius
Nerves- subcostal (12th thoracic nerve), Ilioinguinal, Iliohypogastric
What does it mean if the report for a CT abdomen with contrast states that one of the kidneys is non-enhancing?
Ischaemia following renal artery thrombosis following blunt trauma
Does the left renal vein pass anterior or posterior to the abdominal aorta?
Anterior
Why are injuries to retroperitoneal visceral structures difficult to recognise?
Non specific symptoms. The symptoms resulting from hematoma formation depend on the anatomical position of the patient
What sort of imaging modality should be used to rule out injury to a structure in this space?
FAST scan
How many bones is the pelvis made of?
Three- 2x hip bones and sacrum
What are the three parts of the hip bone?
Ilium, pubis, ischium
Where do the ilium, pubis and ischium fuse together?
Acetabulum (ball and socket joint of the hip bone)
What two ligaments form the greater sciatic foramen?
Sacrospinous and sacrotuberous ligament (attach from sacrum to ischial spines and ischial tubercles)
At what level does the aorta bifurcate?
L4
What are the branches of the internal iliac artery?
I love going places in my very own underwear
Iliolumbar artery
Lateral sacral artery
Gluteal arteries (superior and inferior)
(internal) Pudendal artery Inferior vesical artery (uterine in women) Middle rectal artery Vaginal artery Obturator artery Umbilical
Which four branches of the internal iliac artery exit the pelvic cavity (and therefore are at risk of bleeding)?
Superior and Inferior gluteal arteries
Obturator artery
Inferior pudendal artery
Which foramen does the superior gluteal artery pass though ?
The greater sciatic foramen, above the piriformis muscle
Which foramen does the inferior gluteal artery pass though?
The lesser sciatic foramen, below the piriformis muscle
Which foramen does the internal pudendal artery pass though?
lesser sciatic foramen
Describe three ways that the male and female pelvis differs
1) Women have a wider sub pubic angle than men
2) Broader pelvic inlet and outlet
3) Larger sacral curvature
Which vessels are more likely to haemorrhage with pelvic fractures?
Sacral venous plexus, iliolumbar, internal iliac, superior gluteal, lateral sacral, internal pudendal
Which joint is the internal iliac artery and the sacral venous plexus adjacent to?
Sacroiliac joints
Young male, stabbed in the buttock, BP 50/30
Management?
Pelvic binder over greater trochanters
Definitive = angiographic embolisation w/ orthopaedic fixation if necessary
Would you suspect an anterior or posterior hip dislocation if a patient presented with foot drop?
Posterior due to compression of the sciatic nerve
What are the three categories of pelvic fracture?
Open book
Closed book
Vertical shear
What is the primary threat to life with regards to pelvic fractures?
Haemorrhage. Hypotension + pelvic fractures have a high mortality
What type of fracture commonly presents with a shortened externally rotated leg?
NOF
Do arterial or venous haemorrhage predominate in pelvic fractures?
Venous
What type of pelvic fracture could result in thigh haemorrhage?
Open book fracture which disrupts pelvic floor
How should a patient with a suspected pelvic fracture be examined?
With caution- inspect pelvic region for signs of ecchymosis, asymmetry, wounds.
Gently palpate the pubic symphysis, ischial tuberosities, iliac crests. Palpate the sacroiliac joints.
Examine the lower limbs for any discrepancy and rotation. Check neuromuscular status. Examine the external genitalia for trauma and abdomen.
How could you differentiate between an arterial and venous tear in pelvic fracture?
Monitor their blood pressure- venous bleeds e.g. sacral venous plexus tend to result in a more stable blood pressure than an arterial bleed
What vessel is normally associated with a pubic ramus fracture?
Obturator artery
What is an open book fracture?
Fracture of the pubic symphysis and widening of one of the sacroiliac joints
What sort of fractures result from anterior posterior compression?
Open book fractures
What type of pelvic fracture result from lateral compression of the iliac bone
Closed book fractures- e.g. sacroiliac fractures presenting with splayed legs as gluteal muscles are supported to adducted the hips.
Urethral injuries are a strong predictor of which type of pelvic fracture?
Ramos or pubic symphysis fracture . Would expect in an ASIS fracture
What is pubic diastasis?
Separation of the pubic symphysis
What is the thoracoabdomen ?
“Intrathoracic abdomen”- area delimited by the 4th IC space anteriorly (nips) and the 6th IC space laterally and the 8th IC space posteriorly. Inferiorly delimited by the costal margin.
What does the thoracoabdomen contain?
Diaphragm, thoracic viscera inc. lungs, heart, great vessels and oesophagus. Abdominal organs including the liver and spleen
How is the liver attached to the diaphragm?
By the coronary ligaments (anterior and posterior) and the falciform ligament
What is the bare area and what are its boundaries?
Part of the superior and posterior liver that isn’t covered by peritoneum which is in direct contact with the diaphragm. Surrounded by coronary ligaments
What is the name of the ligament that connects the liver to the stomach? What structures are found in its free border?
Hepatogastric ligament
Hepatic artery proper, hepatic portal vein and common bile duct
What is the blood supply to the liver?
HPV- 75% volume
HAP-25% volume
Each supply 50% of oxygen
What is the venous drainage of the liver?
Hepatic veins (left, middle, right) which join the IVC. The left hepatic vein lies in plane of the the falciform ligament whereas the middle hepatic vein lies in the plane separating the functional lobes
