S7) Anatomy for Dissection — Liver, Jejunum, Ileum, Colon Flashcards

1
Q

Describe the anatomical position of the liver

A

The liver is located in the right hypochondrium and epigastric areas, extending into the left hypochondrium

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2
Q

There are two surfaces of the liver.

Identify them

A
  • Diaphragmatic surface (anterosuperior surface of the liver)
  • Visceral surface (posteroinferior surface of the liver)
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3
Q

The diaphragmatic surface is the anterosuperior surface of the liver.

Describe its structure.

A
  • It is smooth and convex, fitting snugly beneath the curvature of the diaphragm
  • A section is not covered by visceral peritoneum (‘bare area’) of the liver
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4
Q

The visceral surface is the posteroinferior surface of the liver.

Describe its structure.

A
  • It is irregular and flat due to the presence of surrounding organs
  • It lies in contact with the oesophagus, right kidney, right adrenal gland, right colic flexure, duodenum, gallbladder and the stomach
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5
Q

Describe the superior anatomical relations of the liver

A

Superior to the liver is the diaphragm (separating the abdominal cavity from the thoracic cavity)

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6
Q

Describe the anterior anatomical relations of the liver

A

Anterior to the liver is the anterior abdominal wall and ribcage

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7
Q

Describe the posterior anatomical relations of the liver

A

Posterior to the liver are the oesophagus, stomach, gallbladder, first part of the duodenum (the foregut-derived organs)

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8
Q

Describe the structure and function of the various ligaments of the liver

A
  • Structure: formed by a double layer of peritoneum
  • Function: attach the liver to the surrounding structures
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9
Q

Identify the 5 ligaments of the liver

A
  • Falciform ligament
  • Coronary ligaments
  • Triangular ligaments
  • Hepatoduodenal ligament
  • Hepatogastric ligament
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10
Q

Describe the anatomical position of the falciform ligament

A
  • Attaches the anterior surface of the liver to the anterior abdominal wall
  • Its free edge contains the ligamentum teres (a remnant of the umbilical vein)
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11
Q

Describe the anatomical position of the coronary ligaments

A
  • Anterior and posterior folds
  • Attach the superior surface of the liver to the diaphragm
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12
Q

Describe the anatomical position of the triangular ligaments

A
  • Left and right ligaments
  • Attach the superior surface of the liver to the diaphragm
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13
Q

What does the lesser omentum consist of (in relation to the liver)?

A
  • Hepatoduodenal ligament attaches the liver to the duodenum
  • Hepatogastric ligament attaches the liver to the stomach
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14
Q

Describe the attachment of the liver to the inferior vena cava

A

The posterior surface of the liver is secured to the inferior vena cava by hepatic veins and fibrous tissue

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15
Q

What is the name of the fibrous layer covering the liver?

A

Glisson’s capsule

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16
Q

The liver is divided by the attachment of the falciform ligament.

Identify the individual lobes formed

A
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17
Q

Two ‘accessory’ lobes that arise from the right lobe, and are located on the visceral surface of liver.

Identify them

A
  • Caudate lobe
  • Quadrate lobe
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18
Q

Describe the anatomical position of the caudate lobe of the liver

A
  • Located on the upper aspect of the visceral surface
  • Lies between the inferior vena cava and a fossa produced by the ligamentum venosum (a remnant of the fetal ductus venosus)
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19
Q

Describe the anatomical position of the quadrate lobe of the liver

A
  • Located on the lower aspect of the visceral surface
  • Lies between the gallbladder and a fossa produced by the ligamentum teres (a remnant of the fetal umbilical vein)
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20
Q

What is the porta hepatis and what does it do?

A
  • The porta hepatis is a deep fissure between the caudate and quadrate lobes
  • It transmits almost all the vessels, nerves and ducts entering or leaving the liver
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21
Q

Identify the structures in the porta hepatis

A
  • Right and left hepatic ducts (bile)
  • Right and left branches of hepatic artery
  • Hepatic portal vein

NB. Porta hepatis doesn’t transmit the hepatic veins

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22
Q

What does the hepatic artery do and where is it derived from?

A
  • Hepatic artery supplies the liver with arterial blood
  • It is derived from the coeliac trunk
23
Q

What does the hepatic portal vein do?

A

Hepatic portal vein is the dominant blood supply to the liver parencyma, supplying the liver with deoxygenated blood and carrying nutrients absorbed from the small intestine

24
Q

Identify the 3 main tributaries of the hepatic portal vein

A
25
Q

Where is the hepatic portal vein formed?

A

It is formed behind the upper edge of the neck of the pancreas

26
Q

Describe the structure, function and location of the gallbladder

A
  • Structure: peritoneal structure, gastrointestinal organ
  • Function: stores and releases bile
  • Location: right hypochondriac region of the abdomen, lies fossa between the right lobe and quadrate lobe of the liver
27
Q

The gallbladder can usually be divided into three parts.

Identify them

A
28
Q

What is the fundus of the gallbladder?

A

The fundus is the rounded, end portion of the gallbladder; which projects into the inferior surface of the liver

29
Q

What is the body of the gallbladder?

A

The body is the largest part of the gallbladder and is occasionally in contact with the transverse colon and proximal duodenum

30
Q

What is the neck of the gallbladder?

A

The neck is the tapered region which becomes continuous with the cystic duct, leading to the biliary tree

31
Q

What is the biliary tree?

A
  • The biliary tree is the series of ducts through which bile is secreted from the gallbladder into the gastrointestinal tract
  • These ducts extend from the liver, communicating with the gallbladder and pancreas, and end at an opening into the duodenum
32
Q

Describe the anterosuperior, posterior, inferior anatomical relations of the gall bladder

A
  • Anteriorly and superiorly: inferior border of the liver and anterior abdominal wall
  • Posteriorly: transverse colon and the proximal duodenum

- Inferiorly: biliary tree and duodenum

33
Q

Describe the anatomical position of the jejunum and ileum

A
  • Distal parts of the small intestine
  • Intraperitoneal organs (unlike duodenum)
  • Attached to the posterior abdominal wall by mesentery
34
Q

There is no clear external demarcation between the jejunum and ileum although the two parts are macroscopically different.

Where do these structures start and end?

A
  • The jejunum begins at the duodenojejunal flexure
  • The ileum ends at the ileocecal junction
35
Q

What happens at the ileocecal junction?

A
  • The ileum invaginates into the cecum to form the ileocecal valve

- This valve cannot control movement of material into the cecum but prevents reflux of material back into the ileum

36
Q

Distinguish between the ileum and jejunum in terms of the following characteristic features:

  • Position
  • Intestinal wall
  • Vasa recta
  • Arcades
  • Colour
A
37
Q

Describe the arterial supply of the jejunum and ileum

A

The arterial supply to the jejunoileum is from the superior mesenteric artery which arises from the aorta at the level of the L1 vertebrae

38
Q

Describe the arterial distribution to the jejunum and ileum

A
  • SMA moves in between layers of mesentery, splitting into approximately 20 branches
  • These branches anastomose to form loops, called arcades
  • From the arcades, long and straight arteries arise, called vasa recta
39
Q

Describe the venous drainage of the jejunum and ileum

A
  • The venous drainage is via the superior mesenteric vein

- It unites with the splenic vein at the neck of the pancreas to form the hepatic portal vein

40
Q

The large intestine extends from the caecum to the anal canal.

Identify the 4 different parts of the colon.

A
41
Q

Describe three features in the surface anatomy of the colon

A
  • Omental appendices are small pouches of peritoneum, filled with fat, on the colon surface
  • Teniae coli are 3 strips of muscle running longitudinally along the surface of the large bowel
  • Haustra are sacculations produced by the contraction of the teniae coli to shorten the wall of the bowel
42
Q

Midgut-derived structures are supplied by the superior mesenteric artery, and hindgut-derived structures by the inferior mesenteric artery.

Hence, describe the arterial supply of the ascending colon

A

Arterial supply via two branches of the superior mesenteric artery; the ileocolic and right colic arteries

43
Q

Midgut-derived structures are supplied by the superior mesenteric artery, and hindgut-derived structures by the inferior mesenteric artery.

Hence, describe the arterial supply of the transverse colon

A

Arterial supply via branches of the superior mesenteric artery and inferior mesenteric artery:

  • Right colic artery (SMA)
  • Middle colic artery (SMA)
  • Left colic artery (IMA)
44
Q

Midgut-derived structures are supplied by the superior mesenteric artery, and hindgut-derived structures by the inferior mesenteric artery.

Hence, describe the arterial supply of the descending colon

A

Arterial supply a single branch of the inferior mesenteric artery; the left colic artery

45
Q

Midgut-derived structures are supplied by the superior mesenteric artery, and hindgut-derived structures by the inferior mesenteric artery.

Hence, describe the arterial supply of the sigmoid colon

A

Arterial supply via branches of the inferior mesenteric artery; the sigmoid arteries

46
Q

Describe the formation of the marginal artery

A
  • Terminal vessels of the SMA & IMA split into many vessels as they approach the colon
  • Vessels anastomose in loops to form a continuous arterial channel along the length of the colon i.e. the marginal artery
47
Q

From which blood vessels do the vasa recta arise?

A

Vasa recta arise from the marginal artery to supply the colon

48
Q

Describe the venous drainage of the ascending colon

A

Venous drainage via ileocolic and right colic veins, which empty into the superior mesenteric vein

49
Q

Describe the venous drainage of the transverse colon

A

Venous drainage via superior mesenteric vein

50
Q

Describe the venous drainage of the descending colon

A

Venous drainage via left colic vein, which drains into the inferior mesenteric vein

51
Q

Describe the venous drainage of the sigmoid colon

A

Venous drainage via the sigmoid veins which drain into the inferior mesenteric vein

52
Q

Describe 5 gross anatomical differences between the small and large intestines

A
53
Q

How does the inferior mesenteric artery terminate?

A
  • Superior rectal artery is the terminal continuation of the IMA
  • It crosses the left common iliac artery and descends in the mesentery of the sigmoid colon
  • It gives rise to branches that supply the rectum