Abdominal Anatomy Flashcards
At what vertebral level is the transpyloric plane?
L1
At what vertebral level is the subcostal plane?
L3
At what vertebral level is the supracristal plane?
L4
At what vertebral level is the transtubercular plane?
L5
The abdominal cavity extends from
The diaphragm to the pelvic girdle
Which 3 lines separate the 9 regions of the abdomen?
What are their levels?
Midclavicular lines
Subcostal plane (L3)
Transtubercular plane (L5)
What are the 9 regions of the abdomen?
Right/left hypochondrium
Right/left flank
Right/left ilaic fossa
Epigastric
Umbilical
Pubic
Name the muscles of the abdominal wall from superficial to deep
Rectus abdominus
External oblique
Internal oblique
Transversus abdominus
What structure does the external oblique, internal oblique insert into?
Linea alba (at the midline)
Covered by aponeurosis
Which muscle forms the inguinal ligament?
Free border of the external oblique
Where does the inguinal ligament join to at either end?
ASIS
Pubic tubercle
Why is a midline incision to the abdomen not necessarily a good thing?
The linea alba has a poor bloody supply = bad for wound healing = predisposition to herniation
Where is the origin of the internal oblique?
Lower few ribs
Between which muscles is the neurovascular plane of the abdomen?
Between the internal oblique and transversus abdominus
What are the collective functions of the abdominal wall muscles?
Support
Movement
Intra-abdominal pressure- peeing, pooing, coughing, birthing
Name the layers of the abdominal wall from superficial to deep
Skin
Superficial fascia
External oblique
Internal oblique
Transvresus abdominus
Transversalis fascia
Parietal peritoneum
Above the arcuate line, where is the rectus abdominus muscle?
In the rectus sheath, made from the tendons of the other 3 muscles
Where is the arcuate line?
What changes at this point?
Why is this important?
What then sits behind the rectus abdominus?
Around the umbilical area
The rectus abdominus moves behind all 3 aponeurosis of the flat abdominal wall muscles
Allows the rectus abdominus to move away from the midline during pregnancy
Transversalis fascia then sits closest to the rectus abdominus at the back
What arteries/veins are found in the rectus sheath?
Inferior epigastric artery
Inferior epigastric vein
Which arteries meet in the rectus sheath?
Superior and inferior epigastric arteries
Why are the superior and inferior epigastric arteries important in a patient with a narrowed aorta?
They unite the subclavian artery to external iliac vein - forms an arterial shunt
What is incised in a midline incision?
Linea alba
Avascular tissue
What is incised in a paramedian incision?
What muscle would you see either side of the midline?
Rectus sheath
Muscle displaced laterally to spare nerves
Rectus abdominus
When is a Gridiron incision at McBurney’s point used?
Which nerve is at risk?
How do you find McBurney’s point?
Appendectomies
Ilioinguinal and iliohypogastric nerves are at risk
One-third of the distance between the right ASIS and umbilicus
What is at high risk of damage in a subcostal (Kocher) incision?
Superior epigastric artery
A surgeon makes a midline incision of the abdomen. What structures does he come across in order from superficial to deep?
Skin
Subcutaneous fatty layer (Camper’s fascia)
Membranous fascia (Scarpa’s)
Linea alba
Transversalis fascia
Preperitoneal fat
Parietal peritoneum
Where does abdominal wall lymphatic fluid drain to?
Axillary and inguinal lymph nodes
4 points from the umbilicus
What is the gut tube covered in?
A layer of tissue called the peritoneum
When is a structure intra-peritoneal?
When it is covered in peritoneum
e.g. gut tube
When is a structure retro-peritoneal?
When it sits behind the peritoneum
List the retro-peritoneal structures
S = Suprarenal (adrenal) glands
A = Aorta/IVC
D = Duodenum (second and third segments)
P = Pancreas
U = Ureters
C = Colon (ascending and descending only)
K = Kidneys
E = Esophagus
R = Rectum
What is the mesentery?
A fold of peritoneum suspending an organ from the abdominal wall
What is a secondary retroperitoneal structure?
Intraperitoneal structure that later becomes retroperitoneal
Name the 3 main arteries supplying the gut tube
What vertebral levels are they found out?
What regions do they supply?
Coeliac trunk T12 foregut
Superior mesenteric artery L1 midgut
Inferior mesenteric artery L3 hindgut
Which nerves supply the foregut?
Where is their dermatome?
T5 - T9
Epigastric region -
Which nerves supply the midgut?
Where is their dermatome?
T10-T11
Umbilical region
Which nerves supply the hindgut?
Where is their dermatome?
T12-L1
Pubic region
Which dermatome covers the belly button?
T10
Which spinal nerve covers the inguinal ligament?
L1
Which mesentery contains the neurovascular supply to the gut?
Dorsal mesentery
At which vertebral level does the oesophagus start?
C6/7
What type of muscle form the oesophagus?
Upper third = skeletal muscle
Lower two thirds = smooth muscle
What does the oesophagus run posterior to?
Trachea
Left atrium of the heart
At what vertebral level is the oesophageal hiatus?
T11-12
At what vertebral level does the aorta pass through the diaphragm?
T12
At what vertebral level is the pyloric sphincter of the stomach?
What else can be found here?
L1
Renal arteries
Between what vertebral levels does the duodenum run?
L1-L3
What type of mesentery does the foregut have?
Ventral and dorsal mesentery
What type of mesentery does the midgut and hindgut have?
Dorsal mesentery
Where is the lesser omentum?
The peritoneum between the stomach and the liver
What structures can be found in the free lower edge of the lesser omentum?
Common bile duct
Hepatic artery
Portal vein
Where is the greater omentum?
Large loop of dorsal mesentery that hangs off the greater curvature of the stomach, covers the small intestine, then loops back up to attach to the transverse colon
Draw out the branches of the coeliac trunk
Draw it good
Where is the marker for an upper vs. lower GI bleed?
What else does this mark?
Ligament of Treitz
The duodeno-jejunal flexure
Which artery is at risk of perforation with a duodenal ulcer?
Gastroduodenal artery
Which arteries supply the duodenum?
Superior pancreaticoduodenal artery - from the gastroduodenal artery off the coeliac trunk
Inferior pancreaticoduodenal artery - off the SMA
Describe the pain pattern of appendicitis
Early visceral pain refers to the umbilical region
Later stage somatic pain refers to the right iliac fossa
What is the blood supply to the appendix?
Appendicular artery from ileocolic artery of SMA
Which portion of the large intestine refers pain to the umbilical region?
Ascending colon
Which portion of the large intestine refers pain to the pubic region?
Descending colon
Sigmoid colon
Rectum
Draw out the branches of the superior mesenteric artery
What vertebral level?
Draw it good
L1
Draw out the branches of the inferior mesenteric artery
What vertebral level?
Draw it good
L3
What is the cysterna chyli?
Dilated sac at the lower end of the thoracic duct
What is the thoracic duct?
Where does it drain to?
A large lymphatic duct that drains most of the abdomen and lower portion of the body
It drains into the systemic circulation at the angle of the left subclavian and internal jugular veins as a single trunk, at the commencement of the brachiocephalic vein
Why can upper GI cancers cause a left supraclavicular lymphadenopathy?
Lymph drains upwards towards the left subclavian and internal jugular veins. There are valves that prevent backflow
Mets of GI cancers can block the thoracic duct, causing an enlarged Virchow’s node
Where does the rectum receive its blood supply from?
IMA
Internal iliac artery
Where in the rectum is the origin point for classic haemorrhoids?
Internal venous plexus
Where in the rectum is the origin point for external haemorrhoids?
External venous plexus
Pelvic organs covered in peritoneum refer pain to…
T11-L2
Visceral sensory nerves travel alongside sympathetic nerves originating from T11- L2
Pelvic organs below the peritoneum refer pain to..
S2-4
Visceral sensory nerves travel alongside parasympathetic nerves originating from S2-S4
Haemorrhoids are classically reported at what positions?
3, 7, 11 o’clock positions
Which 2 types of nerves stop you from pooing?
Sympathetic - contracts internal sphincter
Somatic (pudendal S2-4) - contracts external sphincter
Which nerve causes you to poo?
Parasympathetic (pelvic splanchnic nerve S2-4) - relaxes internal sphincter and contracts rectal wall
What are the boundaries between the foregut, midgut and hindgut?
FOREGUT
Mouth –> major duodenal papillae (2nd part of duodenum)
MIDGUT
Major duodenal papillae –> 2/3rds along the transverse colon
HINDGUT
2/3rds along the transverse colon –> upper anal canal
What does the falciform ligament contain in utero?
What does this turn into in adults?
Contains the umbilical vein
Ligamentum teres in adults
What is the spleen derived from in utero?
Mesodermal derivative
What is found in the ventral mesentery in utero?
Liver
Gallbladder
Part of pancreas
What is found in the dorsal mesentery in utero?
Spleen
Part of pancreas
Describe the rotation of the stomach and liver in utero
What space does this create?
Stomach rotates to the right 90 degrees and clockwise 90 degrees
Liver moves into the right hypochondrium
Creates the lesser sac - region sitting behind the stomach
What mesentery does the lesser omentum form from?
Ventral mesentery
What mesentery does the greater omentum form from?
Dorsal mesentery
What is the only route in and out of the lesser sac?
The epiploic foramen
The pancreas and duodenum in adults are _______ ______peritoneal
Secondarily retroperitoneal
What are the paracolic gutters?
Why are they clinically important?
Channels that run up the lateral side of the ascending and descending colon from the pelvic cavity to the diaphragm.
Provide a potential route for infection to spread.
When a patient lies down fluid will accumulate on their back
Name the mesentery between the stomach and the liver
Lesser omentum
Where does the greater omentum go between?
The stomach and the transverse colon
Where is the greater sac?
Everything in the peritoneum except for the lesser sac
Where is the supracolic compartment of the greater sac?
Above the transverse colon and in front of the greater omentum
Where is the infracolic compartment?
Below the transverse colon and behind the greater omentum
Where is the surface anatomy marking for the superior surface of the liver?
5th rib at midclavicular line
Follows upper limit of diaphragm
What is the bare area of the liver?
Why is there a bare area of the liver?
An area where the liver touches the diaphragm with no mesentery attached
The liver grows so fast in the ventral mesentery that it grows out the top of it with no mesentery covering it
Name the 4 anatomical lobes of the liver
Left
Right
Caudate (top middle)
Quadrate (bottom middle)
What ‘passes through’ the substance of the liver?
The IVC
What structures can be found in the porta hepatis?
Portal vein
Bile duct
Hepatic artery
Autonomic nerves
How many segments of the liver are there?
Describe the blood supply to the segments
Why is this useful?
8 functionally independent segments of the liver
Has its own hepatobiliary division
Compensatory - segments can be removed with no real loss to the liver - other segments can take over
Which lobe is the bare area of the liver found in?
Right lobe
Where are the coronary and triangular ligaments found?
Coronary ligament - the superior edge of the free border of the liver
Triangular ligaments x2 - pointy bits of the edge of the free border of the liver
Describe the blood supply to the liver
70% from the portal vein
30% from hepatic artery (coeliac trunk)
Hepatic artery runs in the free edge of the lesser omentum
Where does the gallbladder get its blood supply?
Cystic artery
—> hepatic
—> common hepatic
—–> coeliac trunk
What is the Pringle Manoeuvre?
Pinching the free edge of the lesser omentum to cut off the blood supply to the live
What structures can be found in the free edge of the lesser omentum?
Common bile duct
Heptic artery
Portal vein
What organs are drained by the portal vein?
Spleen
Majority of GI tract
Why does the spleen sometimes get enlarged in liver disease?
Liver disease can increase the backwards pressure from the portal vein
Puts back-pressure on the splenic vein, enlarging the spleen
What is the name given to the joining of portal and systemic venous systems?
Which 3 places can they be found?
Port-systemic anastomoses
Inferior oesophagus
Umbilicus
Rectum
Which way does blood shunt if a patient has for example fibrotic liver disease?
Blood shunts from portal venous system to system venous system, causing varices
Where does the gallbladder drain into?
Major duodenal papilla at the 2nd part of the duodenum
Which 2 structures form the bile duct?
Cystic duct
Common hepatic duct
Where is the surface anatomy marking for the gallbladder?
Tip of the right 9th costal cartilage - transpyloric place
What is Murphy’s sign?
During abdo exam - ask patient to breathe out and then gently placing the hand below the costal margin on the right side at the mid-clavicular line.
Make patient breathe in to move abdo contents downwards by the diaphragm.
If the patient stops breathing in (as the gallbladder is tender and, in moving downward, comes in contact with the examiner’s fingers) and winces with a “catch” in breath, the test is considered positive.
Name the space between the liver and the kidney.
Why is this important?
Hepato-renal (Morison’s) pouch
When a patient lies on their back it can spread infection from the abdomen and cause abscesses
Where is the subphrenic space?
Superior to the liver, between the liver and the diaphragm
Where can gallbladder pain refer to?
R hypochondrium
R shoulder (C3-5)
Epigastrum
What is the surface marking for the pancreatic neck?
Transpyloric plane (L1)
What sits near the splenic hilum?
Pancreatic tail
What is the hepato-pancreatic sphincter?
Guards the entrance of the duct of the duodenum
What is the hepato-pancreatic sphincter?
Why is this site important?
Guards the entrance of the duct of the duodenum
Forms the boundary between foregut and midgut
What 2 structures in utero form the pancreas?
Which parts of the pancreas do they form?
Where are they joined to?
Ventral pancreatic bud
- head, thick bit of pancreas
- common bile duct —> major duodenal papilla
Dorsal pancreatic bud
- tail of pancreas
- minor duodenal papilla
What happens to form an anular pancreas?
Ventral bud of the pancreas does not swing back behind the duodenum, but wraps around it causing an obstruction
In which peritoneal cavity region can fluid associated with pancreatitis accumulate?
Lesser peritoneal sac
Where does the pancreas and duodenum get its arterial supply from?
Superior pancreaticoduodenal artery - coeliac trunk
Inferior pancreaticoduodenal artery - SMA
Where does the superior pancreaticoduodenal artery come from?
Coeliac trunk
Where does the inferior pancreaticoduodenal artery come from?
SMA
Describe the lymph drainage of the pancreas and duodenum
Coeliac nodes - thoracic duct - supraclavicular nodes
What is the surface anatomy marking of the spleen?
Left posterior lateral abdominal wall
Ribs 9-11 or 10-12
What is the spleen’s origin?
Mesenchymal origin
Which organs contact the spleen?
Stomach
Pancreas
L kidney
Splenic flecture of the colon
Describe the venous and lymph drainage of the spleen
Splenic vein - contributes to portal vein
Lymph drainage to coeliac nodes
