Abdomen Flashcards
1
Q
Arteries of the abdomen
A
Description:
- Caecum to the splenic flexure is midgut (supplied by the SMA), then becomes the hindgut (supplied by the IMA)
- Part of the rectum is supplied by the internal iliac system and this anastamoses with the lower branches of the inferior mesenteric system
- Arteries pass between layers of mesentery
- Arterial anastamoses occur throughout
Branches:
- SMA
- inferior pancreaticoduodenal artery
- jejunal branches
- ileal branches
- ileocolic artery
- ileal branch that supplies the terminal ileum
- colic branch that supplies the proximal ascending colon
- anterior and posterior caecal arteries
- appendicular artery
- right colic artery
- descending branch that supplies the lower portion of the ascending colon
*
ascending branch which supplies the upper portion of the ascending colon- middle colic artery
- right branch supplies the right portion of the transverse colon
- left branch supplies the left portion of the transverse colon
- middle colic artery
- IMA
- left colic artery
* ascending branch * descending branch * two-to-four sigmoid arteries * superior rectal artery
* terminal branch of the IMA * divides into two terminal branches which descend on each side of the rectum * Marginal artery of Drummond
* continuous arterial circle along the inner border of the colon formed by the anastomoses of the terminal branches of the SMA and IMA * straight vessels (vasa recta) pass from this marginal artery to the colon * important connection between the SMA and IMA providing collateral flow in the event of occlusion or significant stenosis * junction of the SMA and IMA territories is at the splenic flexure * anastomoses here are often weak or absent, hence the marginal artery at this point (known as Griffiths point) is often focally small or discontinuous * for this reason, the splenic flexure is a watershed area prone to ischaemia / infarction * Arc of Riolan * more proximal arterial anastomosis between the SMA and IMA
2
Q
Arterial supply to the liver
A
Description/Features:
* Common hepatic artery is a terminal branch of the coeliac artery * Proper hepatic artery is a branch of the common hepatic artery * The proper hepatic artery runs with the portal vein and the CBD in the hepatoduodenal ligament to the porta hepatis * It terminates by bifurcating into the right and left hepatic arteries before entering the porta hepatitis of the liver * Variations of arterial supply to the liver are common (50% of people)
Common hepatic artery:
* arising from the from aorta (2%) * arising from the from SMA (2%) * trifurcation into RHA, LHA and GDA (~6%)
Right hepatic artery (RHA):
* arising from the coeliac trunk (2.5%) * arising from the SMA (12.5%) - most common * accessory RHA from SMA (4%)
Left hepatic artery (LHA):
* arising from the left gastric artery (7.5%) - second most common * accessory LHA from LGA (7.5%)
Right and left hepatic arteries:
* RHA from SMA and LHA from LGA (1%) * accessory RHA from SMA and accessory LHA from LGA (1%)
3
Q
Biliary tree/pancreatic duct variants
A
Extrahepatic:
* Low insertion of CD into CHD (distal third) * Medial insertion of CD into CHD (traveling anterior or posterior to CHD) * Parallel course between CD and CHD * High insertion of CD into RPD * CD may be adherent to CHD
Intrahepatic:
* RPD emptying into LHD * RPD empyting into lateral side of RAD * Triple confluence of RPD, RAD and LHD * RPD draining into CD * RPD draining into CHD
Pancreatic:
* Complete pancreas divisum * Incomplete pancreas divisum * Anomalous pancreatobiliary junction
4
Q
Vasculature of the kidney
A
Description/Features:
* The kidneys are supplied by the renal arteries, and drained by the renal vein
Origin:
* Renal arteries * arises laterally from the abdominal aorta at the L1-2 vertebral body level (inferior to the origin of the SMA) * Renal veins * formed by the union of two-to-three renal parenchymal veins in the renal sinus
Course/Relations:
* Renal arteries * right renal artery courses inferiorly and passes posterior to the IVC and the right renal vein to reach the renal hilum * left renal artery passes more horizontally, posterior to the left renal vein to enter the renal hilum * ureter is most posterior structure in the renal hilum * Renal veins * emerges from the renal hilum anterior to the renal artery * drains into the inferior vena cava at the level of L2 * left renal vein is much longer (6-7cm) than the right renal vein (3-4cm) * the left renal vein courses anteriorly to the abdominal aorta, under the SMA * At the hilum, the order from superficial to deep is vein, artery, ureter
Branches/Tributaries:
* Renal arteries
* inferior adrenal artery * capsular artery * ureteric artery * terminates by dividing into dorsal and ventral rami * Renal veins
* left renal vein:
* left gonadal vessel * left adrenal vein * sometimes left inferior phrenic * small branches from kidney capsule, proximal ureter and renal pelvis * right renal vein
* small branches from kidney capsule, proximal ureter and renal pelvis
Variations:
* Renal artery * early / perihilar branching * accessory renal arteries * can sub-categorize * accessory artery - supplying the renal hilum * accessory renal arteries most commonly arise from abdominal aorta but can arise from coeliac trunk, SMA, middle colic * aberrant renal artery - supplying inferior pole (more common) * Renal vein * retroaortic left renal vein - renal vein courses behind the aorta to empty into the IVC * circumaortic left renal vein - forms collar around the abdominal aorta * supernumerary renal veins - can affect either kidney * Nutcracker syndrome: compression of the left renal vein between the SMA and aorta, can cause venous hypertension
5
Q
Caecum
A
Description/Features:
* Caecum is a blind-ending sac of bowel, the first part of the large bowel, and lies in the right lower quadrant of the abdomen * Superior margin of the caecum is defined by the ileocaecal ostium * Upper and lower flaps consisting smooth muscle protrude into the lumen around the ostium forming the ileocaecal valve * Above which the large intestine continues as the ascending colon * Caecum measures 6cm in length and can have a maximum diameter of 9cm before it is considered abnormally enlarged * Appendix typically arises from the posteromedial surface, 2cm inferior to the ileocaecal valve * Caecum is covered in peritoneum, except posteriorly * Three longitudinal bands (taenia coli) start from the appendix * The wall is composed of four coats: serosa, muscularis externa, submucosa and mucosa
Relations:
* Anterior - parietal peritoneum, anterior abdominal wall and loops of small bowel * Posterior - iliacus muscle, psoas muscle, femoral nerve, lateral cutaneous nerve of the thigh, appendix (variable) * Medial - ileocaecal valve, terminal ileum, external iliac vein and artery, right ureter * Superior - ascending colon * Inferior - lateral third of the inguinal ligament
Arterial supply:
* Ileocolic artery giving the anterior and posterior caecal arteries
Venous drainage:
* Anterior and posterior caecal veins to the SMV (a tributary of the portal venous system)
Lymph drainage:
* Paracolic lymph nodes which drain to the superior mesenteric lymph node group
Nerve supply:
* Sympathetic supply via superior mesenteric plexus * Parasympathetic supply via pelvic splanchnic nerves (from S2-S4) * Enteric nervous system
Variations:
* Subhepatic caecum - failure of the caecum to migrate to its typical position during midgut rotation in embryogenesis * Mobile caecum - incomplete fixation to the retroperitoneum due to right colonic mesentery failing to fuse to the lateral peritoneum * Retrocaecal, subcaecal, paracaecal, preileal, postileal and pelvic variation of the appendix
6
Q
Common bile duct
A
Description:
* Transmits bile into the duodenum * Along with the cystic duct makes up the extra-hepatic bile ducts * Cystic duct + common hepatic duct = CBD * CBD is approximately 8cm long and usually <6mm wide in diameter
Course/Relations:
* The CBD travels initially in the free edge of the lesser omentum (with proper hepatic artery and the portal vein) * Then courses posteriorly to the duodenum and pancreas to unite with the main pancreatic duct to form the ampulla of Vater * Drains at the major duodenal papillae on the medial wall of the D2 segment of the duodenum * Calot triangle (relation)
Arterial supply:
* Upper part: cystic artery * Lower part: superior pancreatico-duodenal artery
Variants:
* Four main relationships of the CBD with the pancreatic head:
* partially covered posteriorly (most common ~50%) * completely covered * completely uncovered * CBD may pass laterally to the pancreatic head (least common)
7
Q
Developmental abnormalities of the kidney
A
Developmental anomalies of the kidneys
* Number * renal agenesis: congenital absence of one or both kidneys * supernumerary kidney: presence of accessory kidneys * Fusion * horseshoe kidney: fusion across the midline of two distinct functioning kidneys connected by an isthmus of functioning renal parenchyma or fibrous tissue (90% lower poles) * cross fused renal ectopia: kidneys are fused and located on the same side of the midline * pancake kidney: upper and lower poles of the kidneys are fused and usually give rise to two separate ureters, and are usually situated anterior to the bifurcation of the abdominal aorta * Location * pelvic kidney: kidney that is seen fixed in the bony pelvis or across the spine * renal malrotation: anomalous orientation of the renal hilum * nephroptosis: floating kidney, refers to the descent of the kidney >5cm when the patient moves from a supine to upright * intrathoracic kidney: rare form of ectopic kidney (renal ectopia) * Shape * persistent fetal lobulation: incomplete fusion of the developing renal lobules * hypertrophied column of Bertin: extension of renal cortical tissue which separates the pyramids and may be mistaken for a renal mass * hilar lip: infolding of the cortex at the level of the renal sinus (renal cortex appears thicker in this area) * dromedary hump: focal bulges on the lateral border of the left kidney, caused by the splenic impression onto the superolateral left kidney * Vasculature * accessory renal arteries: aberrant renal artery (supplying the superior and/or inferior pole), accessory renal artery (supplying the hilum) * renal vein anomalies: supernumerary renal veins, retro-aortic left renal vein, circumaortic left renal vein * Collecting system * duplex collecting system: incomplete fusion of upper and lower pole moieties resulting in a variety of complete or incomplete duplications of the collecting system (eg. bifid ureter, two ureters) * retrocaval ureter: IVC forms infront of ureter, only affects the right ureter
8
Q
Duodenum
A
Description/Features:
* Duodenum is the first part of the small intestine and is the continuation of the stomach * Duodenum is a 20-30cm C-shaped hollow viscus * Lies at the level of L1-3 * Convexity of the duodenum usually encompasses the head of the pancreas * Duodenum begins at the duodenal bulb and ends at the ligament of Treitz * Continues as the jejunum (duodenojejunal / D-J flexure) * Composed of four parts (D1-4) * Four layers: mucosa, submucosa, muscularis propria (inner circular, outer longitudinal), adventitia
Course:
* D1 (5 cm)
* commences at the pylorus and passes backward, upward, and to the right, beneath the quadrate lobe to the body of the gall-bladder * intraperitoneal for first 2-3 cm * D2 (7.5 cm)
* descends along the right margin of the head of the pancreas, generally to the level of the upper border of the body of L3 * pancreatic duct and CBD enter the descending duodenum through the major duodenal papilla (ampulla of Vater) * also contains the minor duodenal papilla, the entrance for the accessory pancreatic duct * junction between the embryological foregut and midgut lies just below the major duodenal papilla * D3 (10 cm) * takes a second bend, and passes from right to left across the vertebral column * D4 (2.5 cm) * ascends and ends opposite L2 * unites with the jejunum, forming the duodendojejunal flexure * DJ flexure is surrounded by a peritoneal fold containing muscle fibres (ligament of Treitz)
Relations:
* D1
* anteriorly - gallbladder, quadrate lobe of liver * posteriorly - common bile duct, portal vein, gastroduodenal artery * superiorly - epiploic foramen * inferiorly - pancreatic head * D2
* anteriorly - transverse mesocolon * posteriorly - right kidney, right ureter, right adrenal gland * superiorly - liver, gallbladder (variable) * inferiorly - loops of jejunum * laterally - ascending colon, hepatic flexure, right kidney * medially - pancreatic head * D3
* anteriorly - small bowel mesentery root, SMA, SMV * posteriorly - right psoas muscle, right crus of diaphragm, right ureter, gonadal vessels, aorta and IVC * superiorly - pancreatic head / uncinate process * inferiorly - loops of jejunum * D4
* superiorly - stomach * inferiorly - loops of jejunum * posteriorly - left psoas muscle, aorta, left renal vessels
Arterial supply:
* Duodenal cap (first 2.5cm) - supraduodenal artery (branch of gastroduodenal artery) * Remaining D1 to mid D2 - superior pancreaticodudenal artery (branch of gastroduodenal artery) * Mid-D2 to ligament of Trietz - inferior pancreaticoduodenal arteries (branch of SMA)
Venous drainage:
* Duodenal cap (first 2.5cm) - prepyloric vein (drains to portal vein) * Remaining duodenum - superior pancreaticoduodenal vein (drains to portal vein) and inferior pancreaticoduodenal vein (drains to SMV)
Lymph drainage:
* Coeliac Nodes * Superior Mesenteric Nodes
Nerve supply:
* Sympathetic nerve fibres via coelic and superior mesenteric trunks * Parasympathetic nerve fibres via anterior and posterior vagal trunks * Enteric nervous system
Variants
* Duodenal diverticulum - most commonly occurs in D2 or D3 * Duodenal duplication - most commonly occurs at the medial wall of D2 or D3
* appears as a cystic structure that does not communicate with the lumen * Malrotation * Duodenal atresia * Third part can cross as low as L4
9
Q
Epoploic foramen/winslow
A
Foramen of Winslow is the passage of communication between the greater sac (general peritoneal space) and lesser sac (omental bursa)
Borders:
*
Anterior: the free border of the lesser omentum (hepatoduodenal ligament)
* this has two layers and within these layers are the CBD, proper hepatic artery and portal vein (DAVE: Duct, Artery, Vein, Epiploic foramen) * hepatoduodenal ligament + hepatogastric ligament = lesser omentum * Posterior: the peritoneum covering the inferior vena cava * Superior: the peritoneum covering the caudate lobe of the liver * Inferior: the peritoneum covering the commencement of the duodenum and the hepatic artery * hepatic artery passes forward below the foramen before ascending between the two layers of the hepatoduodenal ligament * Left lateral: gastrosplenic ligament and splenorenal ligament
10
Q
Gallbladder and cystic duct
A
Description/Features:
* The gall-bladder is a pear-shaped musculomembranous sac * Divided into a fundus, body, and neck * Extends from the right border of porta hepatis, inferolaterally * Gallbladder consists of four layers: serosa, muscularis externa, lamina propria, mucosa * The cystic duct connects the neck of the gallbladder to the common hepatic duct * Calot's triangle is an anatomic space bordered by the CHD medially, the CD laterally and inferior border of liver * contains Lund's node (lymph node) which may enlarge in cholecystitis * may contain cystic artery, accessory right hepatic artery or anomalous bile ducts within triangle (important surgical implications)
Relations:
* Superiorly: liver * Inferiorly: transverse colon, D2 segment of the duodenum (or pylorus of the stomach) * Anteriorly: liver, transverse colon, 9th costal cartilage * Medial: IVC * The cystic duct travels alongside the cystic artery
Arterial supply:
* Cystic artery (branch of right hepatic artery)
Venous drainage:
* Cystic vein drains directly into the right portal vein
Lymph drainage:
* Nodes at the porta hepatis and portal nodes * Subsequently to the coeliac lymph nodes
Nerve supply:
* Sympathetic: coeliac plexus (passes along the cystic artery) * Parasympathetic: vagus nerve
Variant anatomy:
* Morphology * Phrygian cap: the fundus is sometimes folded back upon itself * Hartmann pouch (infundibulum): neck is focally dilated and probably pathological / related to cholelithiasis * Number * accessory gallbladder * gallbladder bifid / duplication / triplication
* cystic duct may also be duplicated / tripled * gallbladder agenesis * Location
* left-lobe > intrahepatic > retrohepatic * Cystic duct * low cystic duct insertion - into the distal-third of the CHD * medial cystic duct insertion - into the left, not the
11
Q
Inferior mesenteric artery
A
Origin:
* Arising from abdominal aorta at the level of L3 * Close to the lower border of D3
Course/Relations:
* Artery descends anteriorly to the aorta * Then passes to the left as it continues inferiorly * Crosses the left common iliac artery and continues into the pelvis as the superior rectal artery
Termination:
* Terminates as the superior rectal artery
Branches:
* Left colic artery
* ascending and descending branches * Two-to-four sigmoid arteries * Superior rectal artery (terminal branch)
* anastamoses with middle and inferior rectal arteries * Terminal branches of the ileocolic, right, middle, left colic and sigmoid branches form a continuous arterial arcade along the inner border of the colon known as the marginal artery of Drummond with straight arteries known as vasa recta
Supply:
* Hindgut (distal third of the transverse colon to the rectum)
Variation:
* Absent IMA with all its given off by the SMA * Arises from a common trunk with the SMA * May gives extra branches (eg. middle colic or "accessory" renal artery) * Arc of Riolan (second anastamosis in addition to drummond collateral)
12
Q
IVC
A
Description/Features:
* IVC drains venous blood from the lower trunk, abdomen, pelvis and lower limbs to the right atrium of the heart
Origin:
*
Formed by the confluence of the two common iliac veins at the L5 vertebral level
Course:
*
IVC has a retroperitoneal course within the abdominal cavity
*
Runs along the right side of the vertebral column
*
Passes through the diaphragm at the caval hiatus at the T8 level
*
Has a short intra-thoracic course before draining into the right atrium
Relations:
* Anterior: right common iliac artery, mesentery, right gonadal artery, third part of the duodenum, pancreas, posterior surface of the liver * Posterior: vertebral column, right crus of the diaphragm, right inferior phrenic / adrenal / renal and lumbar arteries, right sympathetic trunk * Right: right kidney, right ureter, right adrenal * Left: aorta
Tributaries: * T8: paired inferior phrenic veins * T8: hepatic veins (3) * L1: right adrenal vein * L1: renal veins * L2: right gonadal vein * L1-L4: lumbar veins * L5: common iliac veins (origin)
Variants:
* IVC duplication: IVC continues on both sides of aorta * Transposition of IVC: only one IVC on the left side of the aorta * Azygos continuation of the IVC
* differential for dilated azygos vein * hepatic segment of the IVC is absent * hepatic veins join and drain directly into the right atrium * Circumcaval ureter: IVC develops passing infront of the ureter, so ureter initially courses behind IVC
Tributaries (mnemonic - I Hate GARLIc)
* T8: inferior phrenic veins * T8: hepatic veins (3) * L1: right adrenal vein * L1: renal veins * L2: right gonadal vein * L1-L5: lumbar veins * L5: common iliac veins (origin)
* median sacral vein drains into left common iliac vein, but occasionally drains into junction of left and right common iliac vein
13
Q
Morrison’s Pouch
A
Description:
* Also known as posterior right subhepatic space and hepatorenal fossa * Potential space with no contents in normal conditions * Communicates with the right subphrenic space and right paracolic gutter * Communicates with the lesser sac via the foramen of Winslow * Fluid accumulates here as it is the lowest dependent spaces * Also a preferential site for metastases and abscesses
Boundaries:
*
Anterior: right lobe of the liver and gallbladder
*
Posterior: superior aspect right kidney, right adrenal gland, second part of the duodenum, hepatic flexure, pancreatic head
*
Superior: transverse mesocolon
14
Q
Oesophagus
A
Nerves
- Vagus
- ,Sympathetics
- Meisners
- Aubachs
Arterial in thirds
- Superior and inferior thyroid
- Direct from aorta
- Left gastric
Venous
- ?inferior thyroid
- Azygous/hemiazygous/?accessory
- Left gastric
Lymphatic
- Cervical
- Anterior/posterior mediastinum
- Gastric/coeliac
Muscles/laters
- Constrictors
- Cricopharyngeous
- Mucosa
- Sub mucosa
- Transverse muscle
- Longitudinal muscle
- Outer connective tissue (thin unlike true serosa)
Sphincters
Start
End
Valecular
Piriform fossa
Relations
- Azygous crossing
- Thoracic duct
- Lymph nodes (especially sub carinal and just before hiatus
- Aorta
- Trachea
- ?Superiorly
- Heart
15
Q
Pancreas
A
Description/Features:
* The pancreas is a exocrine and endocrine gland
* serous acini and endocrine Islets of Langerhans * acini secrete various digestive enzymes * alpha islets secrets glucagon, beta islets secrete insulin, delta islets secrete somatostatin * Consists of a head, neck, body and tail * The uncinate process projects left from its lower part * Situated at approximately L1 and lies obliquely * Pancreatic duct travels through pancreatic substance * reaches neck and turns inferiorly and ends at a common orifice with the common bile duct at the major duodenal papilla (7.5-10 cm distal to the pylorus) * accessory pancreatic duct (of Santorini) open into the duodenum ~2.5 cm proximal to duodenal papilla * Mostly retroperitoneal, except tail * Embryology: dorsal and ventral buds fuse
Relations:
* Head/Uncinate process * Lodged within the curve of the duodenum * Posterior: aorta, IVC, CBD, right renal vessels, right crus of the diaphragm, SMA, SMV
* uncinate process passes posterior to the SMV and SMA * Anterior: small bowel * Neck
* Antero-superiorly: pylorus * Posterior: commencement of the portal vein * Body
* Anterior: lesser sac * Posterior: splenic vein, left kidney, left renal vessels, left suprarenal gland * Superior: splenic artery * Tail
* Extends to the splenic hilum * Lies within the lienorenal ligament
Arterial supply:
* Branches from the Splenic Artery * Superior Pancreaticoduodenal Artery (Gastroduodenal Artery) * Inferior Pancreaticoduodenal Artery (SMA)
Venous drainage:
* Drains to the SMV and splenic veins and ultimately portal vein
Lymphatic drainage:
*
Coeliac / Superior Mesenteric Nodes
Nerve supply:
* Spinal Cord Segment T6 to T10 * Vagal Trunks
Variants:
* Pancreas Divisum: MPD drains at minor duodenal papilla (incomplete: communication with duct of Wirsung vs complete: no communication with duct of Wirsung) * Annular Pancreas: ventral pancreatic bud fails to rotate resulting in ring of pancreatic tissue around second part of duodenum * Agenesis of Dorsal Pancreas: failure of the dorsal pancreatic bud to form the body and tail of the pancreas * Ectopic Pancreas: gastric antrum, proximal duodenum, ileum, Meckel's diverticulum * Bifid tail of pancreas / fishtail pancreas: rare branching anomaly of pancreatic tail and duct system
