Abdomen Anatomy Flashcards
What part of the oesophagus is in the abdomen?
Last 1/2 inch
What is the shape of the oesophagus?
Muscular tube
How long is the eosophagus?
25 cm
What’s the origin, course and end of the oesophagus?
From pharynx
Through thorax
Terminates at stomach
What does the oesophagus do?
Conducts food from pharynx to stomach
What is the relationship between the oesophagus, trachea, and vertebral column?
Behind trachea
In front of vertebral column
In what direction does the oesophagus move through the thorax?
Goes forwards and lefT
Where does the oesophagus pierce the diaphragm?
At T10 through opening in right crus
On which side of the stomach does the oesophagus enter?
Right side
What are the two muscular layers of the oesophagus?
Outer longitudinal
Inner circular
Is the entire oesophagus smooth muscle?
No, upper part striated
What tissue is the oesophagus lined by?
Stratified squamous epithelium
Abrupt change to gastric mucosa at gastro-oesophageal junction = Z line
- Clear linear demarcation
What is the narrowing of the oesophagus in the cervical region?
Upper oesophageal sphincter
What is the arterial supply to the oesophagus in the cervical region?
Inferior thyroid artery
What is the venous drainage of the oesophagus in the cervical region?
Brachiocephalic system
What is the lymph drainage of the oesophagus in the cervical region?
Deep cervical nodes
What are the narrowings in the oesophagus in the thoracic region?
Aortic arch
Left main bronchus
What is the arterial supply to the oesophagus in the thoracic region?
Oesophageal branches from aorta
What is the venous drainage of the oesophagus in the thoracic region?
Azygous system
What is the lymph drainage of the oesophagus in the thoracic region?
Mediastinal nodes
What is the narrowing in the oesophagus in the abdomen?
Diaphragmatic orifice
What is arterial supply of the oesophagus in the abdomen?
Left gastric artery from aorta
What is the venous drainage of the oesophagus in the abdomen?
Left gastric portal vein overlaps systemic
What is the lymph drainage of the oesophagus in the abdomen?
Pre-aortic nodes
What can happen to the oesophagus with portal hypertension?
Dilated oesophageal veins = oesophageal varices
If breach mucosa > vomit lots of blood
What is a hiatus hernia?
Protrusion of part of stomach through oesophageal hiatus in diaphragm, up into mediastinum
What type of hiatus hernia is most common?
Sliding (95%)
What is a sliding hiatus hernia?
Top of stomach pushes up
Pulls oesophagus with it
What is a paraoesophageal hernia?
Stomach pushes up beside oesophagus
Connective tissue attachments between margins of oesophageal hiatus and oesophagus stretch up and over stomach
In which quadrant of the abdomen is the stomach?
Left upper quadrant
What does the stomach do?
Storage
Start of digestion of food
What is the shape of the stomach?
J-shaped
What are the two openings of the stomach?
Cardiac opening - oesophagus comes in
- On supramedial aspect
Pyloric opening - end of stomach
What are the two curvatures of the stomach?
Lesser
Greater
What are the two surfaces of the stomach?
Anterior - relates to anterior abdominal wall
Posterior - relates to structures on and of posterior abdominal wall
What is the shape of the pylorus?
Funnel
Describe the pyloric canal
Most tubular part of stomach
Pyloric sphincter very muscular
- Controls gastric outflow into duodenum
What tethers the stomach to the liver?
Lesser omentum = double fold of peritoneum between lesser curvature of stomach and liver
Where does the greater omentum go?
Heads down over rest of viscera, from greater curvature of stomach
Eventually attaches to posterior abdominal wall
Describe the fundus of the stomach
Dome shaped part projecting above cardiac orifice
Usually contains gas bubble
Tucks under left dome of diaphragm
Visible on plain film
Describe the body of the stomach
From cardiac orifice to angular notch on lesser curvature
What is the antrum of the stomach?
Start, and narrowing of pylorus
Describe the gastric folds
Called rugae
Longitudinal muscle folds lining surface
Increase in prominence closer to pylorus
What is the blood supply to the stomach?
Right and left gastric arteries run along lesser curvature
- Run between 2 layers of lesser omentum
- Send branches into surface of stomach
Right and left gastroepiploic arteries run along greater curvature
- Anastomose with each other
- Run between 2 layers of greater omentum
What is the duodenum?
1st part of small intestine
How long is the duodenum?
10 inches
- 2 inches
- 3 inches
- 4 inches
- 1 inch
What is the shape of the duodenum?
C shaped
Where is the duodenum?
Sits back on posterior abdominal wall
Relates to pancreas
- C shaped loop around head of pancreas
Is the duodenum intraperitoneal?
Only 1st inch
Rest retroperitoneal
What does the duodenum do?
Absorption of digested products
Describe the duodenal cap
2 inches
Location of most duodenal ulcers because of imbalance of stomach acid and mucosal defences
Heads up and back to posterior abdominal wall
Sits on right crus
Just medial to right kidney
Describe the part of the duodenum that turns downwards after reaching the posterior abdominal wall
3 inches
Descends next to head of pancreas
Overlies hilar structures of right kidney
Describe the part of the duodenum that becomes horizontal after heading downwards
4 inches Crosses - Right psoas - Inferior vena cava and aorta - Left psoas at level of L3
Describe the fourth part of the duodenum
1 inch Upwards and forwards Curves anteriorly Forms duodenojejunal flexure Attached by fibrous tissue to left psoas
What overlies the second and third parts of the duodenum?
Anterior attachments of mesentaries
What increases the surface area of the duodenum?
Mucosal folds
Where is the common opening of the common bile and pancreatic ducts?
On posteromedial wall at midpoint of 2nd part of duodenum
What is the minor duodenal papilla for?
Opening for accessory pancreatic duct
How long is the jejunum and ileum?
4-6 m
What is the extent of the jejunum and ileum?
Duodenojejunal flexure to ileocaecal junction
What are the relative proportions of the jejunum and ileum?
1st 0% = jejunum
2nd 60% = ileum
Are the jejunum and ileum intraperitoneal or retroperitoneal?
Intraperitoneal
How do the jejunum and ileum connect to the posterior abdominal wall?
By mesentary
What conducts neurovascular structures to the jejunum and ileum?
Mesentary
What is the demarcation between the jejunum and ileum?
No clear demarcation
What quadrant does the jejunum tend to be in?
Left upper quadrant
What quadrant does the ileum tend to be in?
Right lower quadrant
How is the jejunum different to the ileum?
Jejunum
- Larger in diameter
- Thicker walls
- More mucosal folds
What are the differences between the mesentaries of the jejunum and ileum?
Jejunum - Less fat - Few arcades: 1-2 stacks - Long vasa recta Ileum - More fat - Layers of arcades - Short vasa recta
What is at the ileocaecal junction?
Ileocaecal opening
- Mucosa covering thickened smooth muscle
- Covers sphincter
- Controls passage of contents from small to large intestine
What is the relationship between the small and large intestine?
Coils of small intestine centrally placed
Large intestine runs around perimeter of coils
In which quadrant is the ileocaecal junction?
Right lower quadrant
How long is the colon?
1.5 m
Describe the length of the colon
Extends from caecum in right lower quadrant Up Across Down S shaped loop Straightens in pelvis Terminates at anal canal
What does the large intestine do?
Absorption of water and electrolytes from faeces
Describe the outer longitudinal coat of the large intestine
Divided into 3 discrete longitudinal muscle bands = teniae coli
Teniae coli shorter than internal mucosal tube
- Gather up tube > saculated/haustrated appearance
Have fat tags = fat filled peritoneum = epiploic appendices
What is the caecum?
Blind ending part
Hangs down below ileocaecal junction
Has appendix hanging off it
The location of which part of the appendix is constant?
Base
Describe the teniae coli
3 bands - Anterior - Posterolateral - Posteromedial Unite at posteromedial wall of caecum - where base of appendix attaches Corresponds to McBurney's point
What is McBurney’s point?
1/3 along line between anterior superior iliac spine and umbilicus
Corresponds with base of appendix
How long is the appendix?
Normally 6-9 cm
Where is the tip of the appendix?
Anywhere
- Usually tucked up behind caecum = retrocaecal appendix
- 1 in 5 have it in pelvis = pelvic appendix
Where is the ascending colon?
Above ileocaecal junction
On right side
To hepatic/right colic flexure
Where is the transverse colon?
Right angle turn from ascending to transverse colon
Crosses right to left
To under spleen
Turns at splenic/left colic flexure
Where is the descending colon?
Right angle turn from transverse to descending colon
Down left side
Into left lower quadrant
Where is the sigmoid colon?
S-shaped loop at end of descending colon
Drops down into pelvis
Straightens in midline
Where is the rectum and anal canal?
Straight in midline
In pelvis
Fixed terminal part
Where do the teniae coli unit?
At rectum
Where is the site of portosystemic anastomosis in the large intestine?
Anal canal
In which quadrant is the liver?
Right upper quadrant
How does the liver receive the venous drainage from the gastrointestinal tract?
Via portal vein
What is the diaphragmatic surface of the liver?
Anterior and superior parts relate to diaphragm
Domed
What is the visceral surface of the liver?
Poster and and inferior parts
Has
- Imprints of surrounding viscera
- Liver hilum
What divides the diaphragmatic surface of the liver into two unequal lobes?
Falciform ligament
Describe the falciform ligament
Double fold of peritoneum - Has 2 layers Connects liver to anterior abdominal wall Divides diaphragmatic surface into - Small left lobe - Large right lobe
Describe the round ligament, or ligamentum teres, of the liver
At end of falciform ligament
Round fibrous band
Represents obliterated umbilical vein
Connects liver down to umbilicus
Describe the inferior margin of the liver
Sharp
Separates anterior and superior part from posterior and inferior part
Which part of the liver is palpable when the liver is enlarged?
Inferior margin palpable below costal margin
What is the hilum of the liver called?
Porta hepatis
What is the shape of the area around porta hepatis?
H shaped fissure formation
Porta hepatis in centre
What are the structures at the porta hepatis, from anterior to posterior?
Hepatic duct
Proper hepatic artery
Portal vein
What is the hepatic duct?
Duct of liver bringing bile from it
What lobes does the H shaped groove around the porta hepatis form in the liver?
Caudate lobe posteriorly, adjacent to inferior vena cava
Quadrate lobe inferiorly, related to gall bladder
Is the caudate lobe of the liver a discrete lobe?
No, caudate process connects it to right lobe
Which lobes form the left functional half of the liver?
Caudate
Quadrate
Left
Which lobes form the right functional half of the liver?
Right
What are the functional lobes of the liver important for?
Arterial supply
Venous drainage
Bile production
In which groove of the liver is the inferior vena cava located?
In H between right and caudate lobe
Sometimes has own channel
In which groove of the liver is the gall bladder located?
In H between right and quadrate lobe
What does the tip of the gall bladder relate to?
Inferior margin of liver
In which groove is ligamentum teres located?
In H between left and quadrate lobe
What is ligamentum venosum?
Remnant of ductus venosus = shunt between umbilical vein and inferior vena cava
Connects to inferior vena cava
In which groove is ligamentum venosum located?
In H between left and caudate lobe
Into what does the proper hepatic artery divide into at the porta hepatis?
Right and left hepatic artery
Into what does the portal vein divide into at the porta hepatis?
Right and left branch of portal vein
How is venous blood drained from the liver?
Hepatic veins come out of liver, not at porta hepatis
Plug directly into inferior vena cava
Describe the route of bile from the liver to the duodenum
Right and left hepatic duct > porta hepatis > hepatic bile duct > joined by cystic duct from gall bladder > common bile duct > empties into 2nd part of duodenum halfway along posteromedial wall via major duodenal papilla
Where do the structures from the porta hepatis run after leaving the liver?
Between 2 leaves of lesser omentum, near free edge on right side
What is the course of the common bile duct?
1st part at free edge of lesser omentum
2nd part behind 1st part of duodenum
Runs in groove between head of pancreas and 2nd part of duodenum
Enters duodenum
What is the ampulla of Vater?
Where common bile and pancreatic ducts meet
Describe the sphincter surrounding the major duodenal papilla
Complex
Surrounds common opening of common bile and pancreatic ducts
Also surround last part of each individual duct
When digestion not happening > sphincter closed
Bile backs up > enter cystic duct > stored on gall bladder
How is bile released from the gall bladder in response to fatty foods in the small intestine?
Entrance of fatty foods into duodenum Promotes release of CCK CCK stimulates - Contraction of gall bladder - Relaxation of sphincter Concentrated bile released for fat emulsification
What is the shape of the gall bladder?
Pear shaped sack
On which surface is the gall bladder located?
Visceral
What can happen at the site where the gall bladder meets the anterior abdominal wall?
Site of tenderness with gall bladder inflammation
Gall stone erodes through anterior abdominal wall
- Very rare
What is the neck of the gall bladder continuous with?
Cystic duct
Describe the body of the gall bladder
In contact with visceral surface of liver
Narrows to neck
Describe the fundus of the gall bladder?
Rounded tip
Usually projects beyond inferior edge of liver
In contact with anterior abdominal wall
- At lateral border of right rectus abdominis crossing costal margin
What type of gland is the pancreas?
Endocrine
Exocrine
What endocrine substances are released by the pancreas into the blood?
Insulin
Glucagon
Somatostatin
What exocrine substances are released by the pancreas into the pancreatic duct?
Enzymes
Bicarbonate
What is the shape of the pancreas?
Comma
Where is the head of the pancreas located?
Within C shape of duodenum
What is the uncinate process of the pancreas?
Wedge-shaped process of head
Where is the uncinate process of the pancreas?
Tucks behind superior mesenteric vessels
Where is the neck of the pancreas?
Lies over superior mesenteric vessels
Under pylorus of stomach
Where is the body of the pancreas?
Relates to duodenojejunal flexure
- Lies over
Where is the tail of the pancreas?
Next to hilum of spleen
What is the relationship between the pancreas and the vertebral column?
Head and tail either side of vertebral column
What is the relationship between the pancreas and the inferior vena cava and aorta?
Neck and body arch over front of inferior vena cava and aorta
Describe the course of the principal pancreatic duct
Through tail
Across body and neck
Towards head of gland
To duodenum
What does the accessory pancreatic duct drain?
Uncinate process
Where does the accessory pancreatic duct open?
Higher up in duodenum
What is the size of the spleen?
Clenched fist
What happens to the spleen with age?
Involutes
Describe the diaphragmatic surface of the spleen
Smooth
Convex
Tucks under left dome of diaphragm
On which surface is the hilum of the spleen located?
Visceral
What is the delineating margin between the diaphragmatic and visceral surface of the spleen like?
Notched
What structures are at the hilum of the spleen?
Splenic artery
Splenic vein
What is the colic surface of the spleen?
Where splenic flexure of the large intestine occurs
What is the relationship between the spleen and the ribs?
Close to ribs 9-11
Axis along shaft of 10th rib
Broken rib can tear into capsule > massive haemorrhage
What is the relationship between the splenic artery and the pancreas?
Splenic artery passes along upper border of pancreas
Does the splenic vein run with the splenic artery?
Yes
What connects the parietal and visceral layers of the peritoneum?
Series of double folds = mesentary
Is the peritoneal cavity a real or potential space?
Potential
What reduces friction between the two layers of the peritoneal cavity?
Few mLs of serous fluid
What are retroperitoneal structures?
Structures behind peritoneum
Does the parietal peritoneum line the surface of both the anterior and posterior abdominal wall?
No, just anterior
What are intraperitoneal structures?
Structures inside mesentary
Where do the vessels and nerves sit in relation to the peritoneum?
Back on abdominal wall in retroperitoneal space
How do neurovascular structures reach intraperitoneal structures?
Transmitted by mesentary
What is the risk of the mobility provided by the mesentary?
Twisting
What is the nerve supply of the serous membrane?
Shares it with structure it lines
Describe the kind of pain felt in the visceral peritoneum
Has visceral nerve supply
Responds only to stretch
Dull, poorly localised pain
Describe the kind of pain felt in the parietal peritoneum
Has somatic nerve supply
Sharp, severe, well localised pain
Describe the change in pain in acute appendicitis
Walk in with roughly central dull pain
Appendix swelling > stretch receptors of visceral peritoneum refer pain to anterior abdominal wall
As tip of appendix impacts parietal peritoneum > activate somatic nerves
Agonising, localised pain at McBurney’s point
What is the downside of the peritoneal cavity having such a large surface area?
Large potential for large, rapid spread of infection/tumour in cavity over visceral surfaces
What are primary retroperitoneal structures?
Structures in retroperitoneum arranged in layers
Paired structures are most posterior, overlying posterior abdominal wall
- Kidneys
- Ureters
- Adrenal glands
- Aorta and inferior vena cava
On which muscle do the kidneys sit?
Quadratus lumborum
On which muscle do the ureters sit?
Psoas
Describe the relationship between the primitive gut tube and the mesentary
Primitive gut tube has mesentary
Everything that develops from it has dorsal mesentary - at least initially
Ventral mesentary = part of developing gastrointestinal tract had mesentary connecting it to anterior abdominal wall
What are secondary retroperitoneal structures?
Some parts of primitive gut tube come to like back on posterior abdominal wall
Mesentary reabsorbed
Become secondary retroperitoneal structures
- Ascending colon
- Descending colon
- Pancreas
- Duodenum
- Bile duct
Anterior to primary retroperitoneal structures
What are the intraperitoneal structures?
Stomach Jejunum and ileum Transverse colon Sigmoid colon Liver Spleen Gall bladder Caecum
Where does the lesser omentum attach to the abdominal wall?
Diaphragm
What is the relationship between the greater omentum and the transverse colon?
Greater omentum goes on top of transverse colon and transverse mesocolon
How many layers make up the “fatty apron”?
4
- 2 of greater omentum
- 2 of transverse mesocolon
Describe the lesser sac, or omental bursa
Behind stomach
Fluid filled space
Allows stomach extra friction free glide over posterior wall structures
Continuous with greater sac
Can get into it only via omental foramen of Winslow
Portal triad runs in it
What connects the jejunum and ileum to the posterior abdominal wall?
“The” mesentary
Describe “the” mesentary
Large
Fan shaped
Attached in diagonal line
Describe the course of “the” mesentary
From duodenojejunal flexure in left upper quadrant
Over 3rd part of duodenum
Over aorta and inferior vena cava
Over right ureter
Down to ileocaecal junction in right lower quadrant
What is the transverse mesocolon?
Mesentary of transverse colon
Describe the course of the transverse mesocolon
Linear attachment almost horizontal From hepatic to splenic flexure Overlies retroperitoneal structures - Across 2nd part of duodenum - Across neck and body of pancreas
What is the sigmoid mesocolon?
Mesentary of sigmoid colon
Describe the course of the sigmoid mesocolon
Shape of inverted V
Roughly relates to rim of pelvic basin
At apex of V = bifurcation of common iliac vessels
In left lower quadrant
Describe the arrangement of vessels in the mesocolons
Colic arteries feed into and create single marginal artery
Marginal artery runs along edge of mesentary, parallel to colon
Describe the course of the lesser omentum
Comes off lesser curvature of stomach
Connects to visceral surface of liver in region of porta hepatis
- Porta hepatis structures run in free inferior edge
Surrounds liver
Up to diaphragm, on undersurface
Does the lesser omentum surround the whole liver?
No, small bare area superiorly
Describe the course of the greater omentum
Comes off greater curvature of stomach Heads to walls of abdominal cavity Comes right down > goes back up on itself > to posterior abdominal wall Obscures - Jejunum - Ileum - Ascending colon - Descending colon
What is the greater sac?
Synonymous with peritoneal cavity
- Most of peritoneal cavity
Lesser sac/opental bursa = outpouching of greater sac
What is the grastrophrenic ligament?
Greater omentum from highest part of proximal part of greater curvature to undersurface of left dome of diaphragm
What is the gastrosplenic ligament?
Middle part of greater omentum surrounding spleen
Attaches to posterior abdominal wall directly over left kidney
What is the gastrocolic ligament?
Fatty apron
Where is the epiploic foramen, or omental foramen of Winslow?
At free edge of lesser omentum
What does the arterial supply for the abdomen come off?
Abdominal aorta
What is the abdominal aorta a continuation of?
Descending thoracic aorta
Where does the descending thoracic aorta become the abdominal aorta?
Aortic hiatus at T12
Where does the abdominal aorta descend?
In midline on lumbar vertebral colu,m
Where does the abdominal aorta end?
At L4, by dividing into left and right common iliac arteries
From which walls do branches come off from the abdominal aorta?
Unpaired anteriorly
Paired laterally
Paired posteriorly
How many branches come off the anterior wall of the abdominal aorta, and what do they supply?
3 unpaired branches
Supply everything derived from primitive gut tube
How many branches come off the lateral walls of the abdominal aorta, and what do they supply?
3 paired branches Supply paired viscera - Adrenal arteries for adrenal glands - Renal arteries for kidneys - Ovarian/testicular arteries for gonads
How many branches come off the posterior wall of the abdominal aorta, and what do they supply?
2 paired branches
- Phrenic arteries for diaphragm
- Lumbar arteries for abdominal cavity walls
Where do the lumbar arteries run in the abdominal wall?
In neurovascular plane, deep to psoas
Which branch of the abdominal aorta supplies the foregut?
Celiac trunk
Which branch of the abdominal aorta supplies the midgut?
Superior mesenteric artery
Which branch of the abdominal aorta supplies the hindgut?
Inferior mesenteric artery
What structures make up the foregut?
Abdominal oesophagus Stomach 1st part of duodenum down to duodenal papilla Liver Gall bladder Pancreas Spleen
What structures make up the midgut?
Distal duodenum Jejunum Ileum Caecum Appendix Ascending colon 2/3 of transverse colon
What structures make up the hindgut?
Last 1/3 of transverse colon
Descending colon
Rectum
1/2 of anal canal
Describe the cystic artery
Most commonly comes off right hepatic artery
Very variable
Supplies gall bladder and cystic duct
Describe the celiac trunk
Short, wide Not trunk for very long Between aortic hiatus and pancreas - Visible at upper border of pancreas Divides immediately into 3 branches
What are the three branches of the celiac trunk?
Up and left > left gastric artery
Right > common hepatic artery
Left > splenic artery
Describe the left gastric artery
Goes towards diaphragm Slips into upper edge of lesser omentum Turns and supplies branches to - Abdominal oesophagus - Cardio-oesophageal junction Turns down and runs in lesser omentum along lesser curvature of stomach
Describe the splenic artery
Heads directly left from celiac trunk
Tortuous course
Along top of/just behind pancreas’ superior border
Supplies
- Spleen via leinorenal ligament
- Branches to top of greater curvature of stomach
- Gives off left gastroepiploic artery
Where does the left gastroepiploic artery run?
In root of greater omentum
Describe the common hepatic artery
Heads right
Divides at free edge of lesser omentum
Gives off proper hepatic artery
What is the course of the proper hepatic artery?
Given off by common hepatic artery at free edge of lesser omentum
Turns up
Runs with common bile duct and portal vein
In free edge of lesser omentum
To porta hepatis
Divides into left and right hepatic artery
What are the two branches of the common hepatic artery?
Proper hepatic artery
Gastroduodenal artery
What does the gastroduodenal artery supply?
Stomach
Proximal duodenum
Part of pancreas associated with proximal duodenum
What is the right gastroepiploic artery a branch of?
Gastroduodenal artery
What is the posterior superior pancreaticoduodenal artery a branch of?
Gastroduodenal artery
What is the right gastric artery a branch of?
Gastroduodenal artery
At what level does the abdominal aorta give off the superior mesenteric artery?
L1
1 cm below celiac trunk
Where does the superior mesenteric artery run?
In root of “the” mesentary, diagonally across posterior abdominal wall
Where do the branches on the left of the superior mesenteric artery go?
Jejunum and ileum
= jejunal and ileal branches
Where do the branches on the right of the superior mesenteric artery go?
Colon
= colic branches
Which arteries from the superior mesenteric artery feed into the marginal artery running parallel to the colon in the mesocolon?
Ileocolic artery
Middle colic artery
Right colic artery
What is the inferior pancreaticoduodenal artery a branch of, and what does it supply?
Branch of superior mesenteric artery, given off before entering roof of “the” mesentary
Supplies distal part of duodenum and associated part of head of pancreas
What does the middle colic artery supply?
Transverse colon
What does the right colic artery supply?
Right side of colon
Where does the inferior mesenteric artery branch from the abdominal aorta?
Inferior border of 3rd part of duodenum
At L3
In which direction does the inferior mesenteric artery go?
Heads left and down to descending and sigmoid colon, towards left iliac fossa
What are the colic branches of the inferior mesenteric artery?
Left colic artery
Sigmoid colic artery
What does the left colic artery supply?
Ascending branch supplies last 1/3 of transverse colon
Descending branch supplies descending colon
What does the sigmoid colic artery supply?
Sigmoid colon
What is the superior rectal artery?
Name change from inferior mesenteric artery as it passes into pelvis
What does the superior rectal artery supply?
Rectum
Proximal anal canal
What are the two venous drainage systems in the abdomen?
Systemic via inferior vena cava
Portal venous system
What is the portal venous system?
Collects venous drainage from gastrointestinal tract and derivatives
Carries products of digestion to liver for metabolism
What does the hepatic vein drain?
Liver
Drains into inferior vena cava
Which accompanying veins from the abdominal aorta drain directly into the inferior vena cava?
Veins accompany arteries from lateral walls
- Adrenal veins
- Renal veins
- Ovarian/testicular veins
Veins accompanying arteries from posterior wall
- Phrenic veins
- Lumbar veinss
Which accompanying veins from the abdominal aorta drain into the the portal vein?
Veins accompanying arteries from anterior wall
Where is the portal vein formed?
Behind neck of pancreas
The junction of which veins forms the portal vein?
Splenic vein
Superior mesenteric vein
How does the inferior mesenteric vein drain into the portal vein?
Inferior mesenteric vein > splenic vein > portal vein
How do veins from structures supplied by the celiac trunk drain into the portal vein?
Tend to drain directly into it
What is the course of the portal vein?
Behind 3rd part of duodenum
Into free edge of lesser omentum
Up to porta hepatis
Divides into right and left branch for each of functional halves of liver
Does the portal system have valves?
No
Is the portal system low or high pressure?
Low
When can being a low pressure system be a problem for the portal system?
Substance of liver becomes damaged/fibrosed
Passage of portal venous blood gets harder into liver
Portal hypertension
Because valveless, potential for reverse flow
Looks for alternative way into inferior vena cava, which is not via liver and hepatic veins
Finds that in sites of portosystemic anastomoses
Opens up anastomotic channels
- Hugely dilate
What are the five sites of portosystemic anastomosis, and how do they present pathologically in portal hypertension?
Distal oesophagus: with azygous vein system
- Oesophageal varices
- Retching/vomiting can rip them open
- Present with massive haematemesis
Anal canal: superior rectal vein and inferior and middle rectal veins with iliac system
- Present as haemarrhoids
Umbilicus: periumbilical region has paraumbilical veins from ligamentum teres > umbilical vein re-canalises with lumbar veins of anterior abdominal wall
- Present as caput medusi
Ascending and descending colon: in retroperitoneal spaces anastomotic channels can open and meet with posterior abdominal wall veins that drain into inferior vena cava
- Only visible post mortem
Bare area of liver
- Only visible post mortem
Which branch of the peripheral nervous system innervates the abdominal viscera?
Autonomic nervous system
Where are preganglionic sympathetic fibres supplying the abdominal viscera derived from?
T6-L2
Where do the sympathetic ganglia for the abdominal viscera cluster?
Around unpaired branches of aorta and renal arteries
What is the parasympathetic innervation for the abdominal viscera?
Vagust to foregut and midgut
Pelvic splanchnics for hindgut
How do sympathetic postganglionic fibres pass to the abdominal viscera?
With blood vessels
Which levels of preganglionic sympathetic fibres supply each section of the abdominal viscera?
Foregut = T6-9 Midgut = T8-12 Hindgut = T12-L2
To where is pain referred from all unpaired abdominal viscera proximal to the mid-sigmoid colon?
Midline of anterior abdominal wall
To where is pain referred from all unpaired abdominal viscera distal to the mid-sigmoid colon?
Perineal region
What are the layers of the anterior abdominal wall, from superficial to deep?
Skin Superficial fascia - fatty layer (Camper's fascia) Superficial fascia - membranous layers (Scarpa's fascia) External oblique Internal oblique Transversus abdominis Transversalis fascia Extraperitoneal fat/fascia Parietal peritoneum
What does the parietal peritoneum line?
Walls of cavity
Reflects off wall onto viscera
What are the bony attachments for the abdominal muscles?
Costal margin
Iliac crest
Anterior superior iliac spine
Pubic crest and tubercle
How do the three layers of muscle of the anterior abdominal wall change from lateral to medial?
Fleshy laterally
Aponeurotic medially
Where does the testis develop?
In posterior abdominal wall, in extraperitoneal fat layer
Describe external oblique?
"Front pocket" muscle Outermost layer Overlaps costal margin Goes over anterior surface of ribs Lies edge to edge with attachments of pectoralis major and serratous anterior
How do the two external oblique muscle meet anteriorly?
In midline: 2 aponeuroses meet > knit together > form vertical white line = linear alba
What is external oblique’s posterior attachment?
Attaches to thoracolumbar fascia = fascia of posterior abdominal wall
What is external oblique’s inferior attachment?
Iliac crest and anterior superior iliac spine
Jumps in attachment before attaching to pubic crest
What is the inguinal ligament?
Free inferior edge of external oblique
Thickened and rolled inwards
What is the extent of the inguinal ligament?
Anterior superior iliac spine to pubic tubercle and crest
What is the superficial inguinal ring?
Triangular opening in external oblique aponeurosis
Just above and lateral to pubic tubercle
Spermatic cord goes through it
Describe the internal oblique muscle
“Back pocket” muscle
Attaches to
- Costal margin above
- Thoracolumbar fascia behind
- In anterior midline meets internal oblique aponeurosis of other side at linear alba
- Anterior half of iliac crest
- Lateral 2/3 of inguinal ligament
Lowermost fibres, instead of inserting at linear alba
- Arch upwards, over, and downwards into pubic crest
Describe transversus abdominis
Horizontal fibres
Underlaps costal margin
- Continuous with diaphragm
Behind to thoracolumbar fascia
In front, aponeuroses interdigitate at linear alba
Attaches to anterior half of iliac crest
Lowermost fibres arise from lateral 1/3-1/2 of inguinal ligament
Arches upwards, over, and downwards to insert into pubic crest via conjoined tendon with internal oblique
Describe rectus abdominis
Vertical fibres Attaches to pubic bone inferiorly Ascends and widens > divergent muscle Overlaps costal margin Attaches to anterior chest wall at costal cartilages 5-7 Edge to edge with pectoralis major
What are the three tendinous intersections of rectus abdominis?
Divides muscle into 4 short segments > gives strength 1 at - Umbilicus - Xiphysternum - Halfway between
What encloses rectus abdominis?
Aponeurotic sheath
Where does the posterior layer of the rectus sheath stop?
Arcuate line, 1 inch below umbilicus
Describe the rectus sheath
Above arcuate line, aponeurosis of
- External oblique in front
- Internal oblique splits into anterior and posterior leaf
- Anterior leaf in front
- Posterior leaf behind
- Transversus abdominis behind
Below arcuate line, posterior sheath disappears, and all 3 aponeuroses in front
How is the nerve supply to the anterior abdominal wall organised?
In linear bands, following dermatomes
What level innervates the umbilicus?
T10
What level innervates the groin?
L1
What levels innervate the thoracic cage?
T1-6
What levels innervate below the thoracic cage and above the umbilicus?
T7-9
What levels innervate below the umbilicus and above the groin?
T11-12
What are the two branches of the internal thoracic artery, and where do they split off?
At costal margin divides into
- Musculophrenic artery
- Superior epigastric artery
What is the course of the musculophrenic artery?
Follows costal margin and continues to feed off anterior intercostal arteries
What is the course of the superior epigastric artery?
Heads down to supply structures of anterior abdominal wall
Slips into rectus sheath: runs in posterior sheath/through rectus abdominis
Meets inferior epigastric artery
What is the course of the inferior epigastric artery?
Branch of external iliac artery
Slips into posterior rectus sheath
Meets and anastomoses with superior epigastric artery
What do the superior and inferior epigastric veins follow?
Follow back to internal thoracic vein and external iliac vein
Venous drainage mirrors arterial supply
Is the anterior abdominal wall a site of porto-systemic anastomosis?
Yes
See caput medusi with portal hypertension
What is the inguinal region?
Transition zone between lower abdomen and upper thigh
Demarcated by inguinal ligament
What is the lacunar ligament?
Extension of inguinal ligament to pectineal line
What is the inguinal canal?
Inguinal region part of passage of testis through anterior abdominal wall as it moves towards scrotum
Slit-like passage extending downwards and medially above and parallel to medial half of inguinal ligament
Is the skin and superficial fascia of the anterior abdominal wall continuous with the scrotum?
Yes
What does the transversalis fascia line?
Lateral anterior abdominal wall muscles and rectus abdominis
As it tracks towards the inguinal region, what layers of the anterior abdominal wall does it penetrate?
Transversalis fascia
Transversus abdominis
Internal oblique
External oblique
Where is the deep inguinal ring?
Halfway between anterior superior iliac spine and pubic tubercle, hole in transversalis fascia made
What happens after the testis enters the deep inguinal ring?
Has only penetrated 1st layer of abdominal wall
Turns downwards and medially to superficial inguinal ring
What is the floor of the inguinal canal?
Inguinal ligament
What is the roof of the inguinal canal?
Arching fibres of internal oblique and trasversus abdominis
What is the anterior wall of the inguinal canal?
External oblique aponeurosis
Laterally, internal oblique muscle
What is the posterior wall of the inguinal canal?
Transversalis fascia
Medially, conjoined tendon
What are the layers of the spermatic cord?
Through transversalis fascia: internal spermatic fascia
Beneath internal oblique and transversus abdominis: cremasteric fascia
- Also picks up muscle fibres, especially from internal oblique - forms cremaster muscle
Through superficial inguinal ring: external spermatic fascia from external oblique
What does the cremaster muscle do?
Retract testes in cold temperature
What is a hernia?
Protrusion of abdominal contents through abdominal wall
What is an indirect inguinal hernia?
Protrusion through deep ring into inguinal canal - and sometimes down into scrotum
Which people are especially at risk of developing an inguinal hernia?
Chronic cough
Constipation
Lifting heavy weights
Are inguinal hernias more common in males or females?
Males
How can you see if it’s an inguinal hernia?
Can push contents back with fingers through inguinal canal into abdominal cavity:
Put fingers over deep inguinal ring > get them to cough > remove fingers > cough again > watch hernia develop
What is the processus vaginalis?
Testis and spermatic cord take outpouching of peritoneum with them
Normally, closes over - communication with peritoneum fuses and lost
Why do indirect hernias arise?
Incomplete closure of processus vaginalis > herniated peritoneal contents extend into scrotum/labia
Why don’t you get a hernia every time you cough?
Internal oblique and transversus abdominis close off inguinal canal
What is a direct inguinal hernia?
Protrusion forwards into inguinal canal through area of weakness in its posterior wall
What is the bony framework for the posterior abdominal wall?
From 12th rib
Adjacent to T12-L5
To posterior aspect of iliac crest
Which muscle is an organiser of the posterior abdominal wall?
Psoas major
What is the relationship between the vessels supplying the posterior abdominal wall and psoas major?
Vessels behind psoas
Where is the lumbar plexus?
Withing substance of psoas
What overlies psoas major?
Psoas minor, if present
Sympathetic trunks
What is the relationship between psoas major and the vertebral column?
Psoas edge to edge with vertebral column
Obscures transverse processes
Describe psoas minor
Overlies psoas major
Short belly
Long tendon
Only in 2/3 of people
Describe quadratus lumborum
Under line of 12th rib
Above iliac crest
Lateral to psoas major
Rectangular
Describe iliacus
Edge to edge with psoas
Underneath quadratus lumborum
What are the attachments of quadratus lumborum?
Posterior half of iliac crest
Tips of lumbar transverse processes
Inferior aspect of 12th rib
What does quadratus lumborum do?
Stabilises 12th rib during expiration
Laterally flexes spine
What are the attachments of iliacus?
Arises from entire iliac fossa
Converges into same tendon as psoas major = tendon of iliopsoas
Inserts into lesser trochanter
What are the attachments of psoas major?
One continuous origin from bottom of T12 to L5
Vertebral bodies, discs, and medial end of transverse processes
Fibres pass beneath inguinal ligament and insert into lesser trochanter
What does psoas major do?
Powerful flexor of spine and hip
What encloses all posterior abdominal wall muscles?
Very dense fascial envelope
Gives attachment to parietal peritoneum
Does external oblique attach to the thoracolumbar fascia?
No, has free posterior edge, because latissimus dorsi intervenes
What are the three layers of the fascia of the lumbar region?
Posterior: attaches to tip of spinous process
Middle: attaches to tip of transverse process
Anterior: cones from front of transverse process
All 3 fuse at tip of 12th rib
What are the two compartments created by the fascia of the lumbar region?
Posterior: between posterior and middle layer
- Contains erector spinae
Anterior: between middle and anterior layer
- Contains quadratus lumborum
Where are the kidneys?
Lateral to vertebral column - Adjacent to T12-L3 In front of 12th rib Closely related to diaphragm - Move with it In paravertebral gutters On quadratus lumborum
Which kidney is higher?
Left, because on right, liver above
How can the kidneys be reached?
Posteriorly, on either side of vertebral column - get into retroperitoneal space without going into cavity
Can take out 12th rib to get to them
What is the physical appearance and size of the kidneys?
Reddish brown
Bean shaped
10 cm x 5 cm x 2.5 cm
What is the relationship between the adrenal glands and the kidneys?
Adrenal glands sit superiorly on kidneys
- Crescent on left
- Pyramid on right
Describe the hilum of the kidney
Faces medially and anteriorly
Transmits neurovascular structures and duct
Connected with fat-filled space = renal sinus
What is the organisation of structures at the hilum of the kidney, from anterior to posterior?
Renal vein
Renal artery
Ureter
Describe the renal artery
1 to each kidney
Branch off abdominal aorta at right angles
Left renal artery arises a little higher than right
How does the renal artery branch inside the kidney?
Classically branches into 5 segmental arteries
Each supplies functional kidney segment
Can remove 1 functional segment without affecting others
How does the right renal artery cross the inferior vena cava to reach the right kidney hilum?
Goes behind
How does the left renal vein cross the abdominal aorta to reach the left kidney hilum?
Goes in front
What is the arterial supply of the ureters?
Not 1 artery
Gets ureteric branches from vessels it passes
What are the narrowings in the ureter, where kidney stones can get stuck?
Renal pelvis to ureter
Kinked when passes over pelvic brim
Oblique passage through bladder wall
