Nerves, Vessels, and Lymphatics of the Abdomen

Question 1

Where does the abdominal aorta begin and end.

Answer 1

Begins in the midline at T12/L1 and ends anterior to L4 by dividing into right and left common iliac arteries.

Question 2

How many branches does the abdominal aorta have as it descends into the abdominal cavity?

Answer 2

3. Anterior, lateral, posterior

Question 3

How many anterior branches down the abdominal aorta have, and what do they supply?

Answer 3

3 anterior, unpaired branches (1) coming off the front of the aorta supply the unpaired viscera of the GIT (all of the derivatives of the primitive GIT

Question 4

How many lateral branches down the abdominal aorta have, and what do they supply?

Answer 4

3 lateral pairs of branches (2) coming off the side of the aorta and they supply the paired viscera (kidneys, adrenals and gonads (testes in male and ovaries in female)). Note that the ureter derives its supply from adjacent structures as it descends, not directly from the abdominal aorta.

Question 5

What do the posterior branches of the abdominal cavity supply?

Answer 5

Series of paired, posterior branches- all of which supply the walls of the abdominal cavity (including the diaphragm). Will supply the diaphragm first before tracking around to the posterior abdominal wall.

Question 6

What is the faciform ligament and what part of the primitive gut tube is it?

Answer 6

Ventral mesentery is only in the proximal part of the primitive gut tube, this becomes the falciform ligament.

Question 7

What are the 3 components of the primitive gut tube?

Answer 7

foregut, midgut and hindgut.

Question 8

What are the 3 branches coming off the primitive aorta and what component of the primitive gut tube do they supply?

Answer 8

The Celiac trunk is the artery of the foregut.
The Superior mesenteric artery supplies the midgut.
Inferior mesenteric artery supplies the hindgut.

Question 9

What structures make up the foregut?

Answer 9

includes everything from the abdominal oesophagus to the major duodenal papilla- the abdominal oesophagus, the stomach and the proximal duodenum down to 1⁄2 way along the second part, but also the liver, gall bladder, pancreas and spleen (which the foregut also gives rise to.)

Question 10

What structures make up the midgut?

Answer 10

The midgut, is continuing on from the major duodenal papilla from the distal part of the duodenum, the jejenum and ileum, caecum and ascending colon, and most of the transverse colon.
- NOTE: There is no sharp line of demarcation between the midgut and hindgut, but it is just short of the splenic flexure- so includes the ascending and most of the transverse colon.

Question 11

What structures make up the hindgut?

Answer 11

The hindgut is the point just short of the splenic flexure in the transverse colon, then descending colon, sigmoid colon, rectum and anal canal.

Question 12

What are the 3 branches of the celiac trunk?

Answer 12

1. Splenic artery
2. Left gastric artery
3. Common hepatic artery

Question 13

What is the passage of the splenic artery?

Answer 13

Heads directly to the left. Has a tortuous course, characterized by lots of curves and even loops along the superior border of the pancreas (retroperitoneal structure). Occasionally tucked in behind the top of the pancreas. Heading, along with the tail of the pancreas, to the hilum of the spleen. It is the main arterial supply to the spleen, but also to the pancreas, as indicated by its position.

Question 14

What does the splenic artery give rise to?

Answer 14

Also gives a series of short branches to the fundus of the stomach, called the SHORT GASTRIC ARTERIES and has a branch which turns along the proximal greater curvature, called the LEFT GASTROEPIPLOIC ARTERY.

Question 15

What is the passage of the left gastric artery?

Answer 15

Heads up and to the left, giving oesophageal branches to the abdominal oesophagus before turning and running along the lesser curvature to give the left gastric artery to contribute to the anastomosis (along with right gastric artery) of the lesser curvature of the stomach.

Question 16

What is the passage way for the common hepatic artery?

Answer 16

It turns right and then divides. Must not only supply the liver, but also the gall bladder, the distal part of the stomach, and the first part of the duodenum. Since it is ‘common’ hepatic artery, going to do more than hepatic artery proper would do.

Question 17

What are the branches of the common hepatic artery? Explain their passage as you discuss their names.

Answer 17

Heads towards the liver to the site of the free edge of the lesser omentum, where it divides into the PROPER HEPATIC ARTERY which will ascend in the free edge of the lesser omentum to the porta hepatis, where it will divide into RIGHT AND LEFT HEPATIC ARTERIES to supply the right and left lobes of the liver. There are usually two extra branches of the proper hepatic artery- the CYSTIC ARTERY comes off the right hepatic artery to the gall bladder (but may come off left hepatic artery or hepatic artery). Proper hepatic artery also gives off the RIGHT GASTRIC ARTERY, which most commonly turns and runs along the lesser curvature to anastomose with the left gastric artery. Other terminal branch of the common hepatic artery is the GASTRODUODENAL ARTERY which has left to supply the greater curvature of the stomach and the proximal part of the duodenum and associated head of the pancreas. Tracking behind the first part of the duodenum, the gastroduodenal artery will then give rise to the RIGHT GASTROEPIPLOIC ARTERY which will run along the greater curvature and anastomose with the left gastroepiploic from the splenic artery. Also the SUPERIOR PANCREATIOCDUODENAL ARTERY- which passes behind to supply the first part of the duodenum (superior) and the head of the pancreas.

Question 18

Where does the superior mesenteric artery arise and travel too?

Answer 18

Arises 1 cm below the celiac trunk, at L1. Travels along the route of the mesentery on the diagonal line through which it attaches to the posterior abdominal wall.

Question 19

What are the branches of the superior mesenteric artery?

Answer 19

Gives off an INFERIOR PANCREATICODUODENAL ARTERY irst to supply the last part of the duodenum (from the duodenal papilla onwards) and pancreas. As it goes along the posterior abdominal wall, sends all of the branches of the small intestine to the left and all of the branches of the large intestine to the right.
=All of the jejunal and ileal branches come off the left and enter the double fold of peritoneum in that diagonal line along the posterior abdominal wall and head up to the coils of the jejenum and ileum.
=Colic branches coming off the right hand side to the components of the large intestine that are derived from the midgut. ILEOCOLIC ARTERY supplies the first part of the large intestine (cecum, appendix, and the first part of the ascending colon) and then the RIGHT COLIC ARTERY.

Question 20

Where does the inferior mesenteric artery arise from and travel to?

Answer 20

Arises at the inferior border of the third part of the duodenum, below the third or horizontal part of the dudoneum corresponding to L3.

Question 21

What branches does the inferior mesentertic artery give off?

Answer 21

Gives off a series of COLIC branches to the components of the large intestinal tract and then changes its name and becomes the SUPERFICIAL RECTAL ARTERY, coming from the rectum from above and entering the pelvis.

Question 22

What is the venous drainage of all the structures derived from the primitive gut tube? i. e those supplied by the unpaired branches of the abdominal aorta

Answer 22

Drain through the portal system of veins, which unite to form a single portal vein posterior to the neck of the pancreas at L2.

Question 23

What is the portal vein formed by?

Answer 23

Portal vein is formed by the superior mesenteric and the splenic vein, which the inferior mesenteric vein joins.

Question 24

How does the portal vein travel?

Answer 24

Portal vein ascends behind the first part of the duodenum, then in the free edge of the lesser omentum (as part of the portal triad with hepatic artery and bile duct system) and then enters the liver at the porta hepatis.
=Enters the liver, where it spills its blood containing digestive products and nutrients into the hepatic sinusoids for processing, it then enters the hepatic veins.

Question 25

What are the Hepatic veins, and where do they drain?

Answer 25

Tributaries of the IVC that directly return the venous blood from the liver to the IVC because of its position in a groove on the visceral surface of the liver, just below the diaphragm.
- Just as hepatic vein drains to the IVC, it pierces the diaphragm through the caval orifice to drain into heart.

Question 26

The venous drainage of structures supplied by the paired branches of the abdominal aorta drain into?

Answer 26

Directly into the IVC.

Question 27

Veins from the middle part of the oesophagus drain into….?

Answer 27

SVC via caval system

Question 28

Veins from the lower part of the oesophagus drain into….?

Answer 28

Portal vein

Question 29

Why do we have porto-systemic anastomoses?

Answer 29

If portal vein blood builds up into the lower part of oesophagus, there is the potential to open up anastomtic channels and push the blood back through the venous drainage above into the SVC instead.

Question 30

What are the porto-systemic anastomoses?

Answer 30

(1) Lower end of the oesophagus, where the tributaries of the left gastric veins back up due to the portal hypertension and instead goes via the azygous vein to the SVC. This results in dramatically and visibly dilated oesophageal mucosal veins called oesophageal varices. These can be torn heavy coughing/ wreching, leading to catastrophic bleeding (vomit out blood).
(2) At the anus, where the superior rectal vein becomes inferior mesenteric vein. In the anal canal, there is some venous drainage into the portal system but the very lowest end of anus drains via middle and inferior veins into IVC (caval system). If portal system is blocked and blood is backing up, finds escape route through inferior and middle rectal veins and into IVC. Patients get huge hemroids (dilated anal veins).
(3) Superficial veins in the anterior abdominal wall also represent an alternative escape route. Associated with the ligamentum teres in the falciform ligamentum (connecting the liver to the anterior abdominal wall) are some para umbilical veins which can open up and allow blood to escape the portal system, to the superficial veins on the anterior abdominal wall which will drain into the lumbar veins via the IVC.
(4) Retroperitoneal viscera. Even though they are draining into the portal vein, if the cannot get their blood supply into the portal system they can push it via the back through the posterior abdominal wall and drain into the caval system that way.
(5) Bare area of the liver

Question 31

What nerves supply the conjoined tendon?

Answer 31

Ilioinguinal and iliohypogastric

Question 32

Where does the testes venous plexus drain into?

Answer 32

On the left hand side, the testicular vein will drain into the left renal vein and on the right hand side it will drain into the IVC.

Question 33

The abdominal viscera are innervated by which nervous system?

Answer 33

Autonomic Nervous System

Question 34

Which nerve fibres derive from T6-T12?

Answer 34

Preganglionic sympathetic fibres

Question 35

Parasympathetic innervation to the foregut, midgut and hindgut is by?

Answer 35

Foregut + Midgut = Vagus nerve

Hindgut = pelvic splanchnics

Question 36

Postganglionic fibres supply foregut, midgut, and hindgut from which nerves

Answer 36

Foregut = T6-T9
Midgut = T8 -T12
Hindgut = T12 - L2

Question 37

Afferent fibres carrying pain from UNPAIRED abdominal viscera proximal to the mid-sigmoid will refer pain where?

Answer 37

Refer pain to the midline of anterior abdominal wall (dermatomes T6 - L2)

Question 38

Afferent fibres carrying pain from UNPAIRED abdominal viscera mid-sigmoid down will refer pain where?

Answer 38

Refer pain to perineal region(dermatomes S2 - S4)