GI Anatomy Flashcards
(146 cards)
1
Q
What is the abdominal cavity and thorax separated by?
A
The diaphragm
2
Q
Which cavity lies inferior to the abdomen and is continuous with it?
A
The pelvic cavity
3
Q
What organs does the abdominal cavity contain?
A
- Gastrointestinal tract (Stomach, small intestine, large intestine, esophagus)
- Hepato biliary system (Liver, bile duct, gallbladder)
- Endocrine system (adrenal gland, pancreas)
- Great vessels (abdominal aorta, inferior vena cava, and their branches)
- Urinary system (kidneys and ureters)
- Spleen (a haematopoietic and lymphoid organ)- it controls the level of blood cells (it removes old or damaged red blood cells) and fights invading germs in the blood (has infection fighting white blood cells)
4
Q
What are the anterior, posterior and lateral walls of the abdominal wall composed of?
- What else contributes to the structure of the posterior abdominal wall?
A
- Skin
- Subcutaneous tissue
- Muscles and their associated aponeurose (flat tendons)
- The 5 lumbar vertebrae contributes to the posterior abdominal cavity
5
Q
What are the 3 functions of the abdominal wall?
A
- To protect abdominal viscera
- To increase intraabdominal pressure (for things like defecation and birth)
- Maintains posture and moves the trunk (abdomen)
6
Q
What are the layers from the skin to the parietal peritoneum?
Additionally, what does the the 3 muscle layers aponeurose to form?
A
- Skin
- Subcutaneous tissue
- External oblique (and fascia)
- Internal oblique (and fascia) (and rectus abdominis should be same depth)
- Transversus abdominis
- Transversalis fascia
- Parietal peritoneum
- The rectus sheath is formed by fascia from the 3 muscle layers, with the rectus abdominis lying within it.
(PICTURE ON GOOGLE DOCS)
7
Q
What are the boundaries of the abdominal cavity?
A
- Xiphisternum
- Costal margin
- Iliac crests
- Anterior superior iliac spine (ASIS)
- Pubic tubercle (a point of attachment for inguinal ligament)
- Pubic symphysis (fibrocartilaginous joints connecting the two hip bones anteriorly)
(PICTURE ON GOOGLE DOCS)
8
Q
Where does the line separating the abdomen into 4 main quadrants lie?
A
Vertical line- Runs in the midsternal line from the xiphisternum, through the umbilicus, to the pubic symphysis
Horizontal line- Runs across the abdomen through the umbilicus.
9
Q
Why would you divide the abdomen into 9 regions rather than using the 4 main quadrants?
A
- This is to be more precise when describing the site of a patient’s pain, or the location of tenderness, mass, swelling, injury, etc during an examination
10
Q
How are the 9 regions drawn?
A
- Vertically, from the left and right midclavicular line from the midclaviclular point to the mid-inguinal point
2 horizontal lines - SUBCOSTAL line- horizontal line drawn through the inferior most parts of the right and left costal margin (through the 10th costal cartilage)
- INTERTUBERCULAR line- horizontal line drawn through the tubercles of the right and left iliac crests at the level of L5.
11
Q
What are the terms of the 9 regions?
A
- Epigastrium
- Left and right hypochondrium
- Umbilical region
- Left and right lumbar
- Hypogastric/suprapubic region
- Left and right illiac fossa
12
Q
What is the transpyloric plane?
A
A horizontal line passing through the tips of the left and right 9th costal cartilage.
It cuts through the pylorus of the stomach, the gallbladder, the pancreas and hila of the kidneys
13
Q
What is the transumbilical plane?
A
Unreliable landmark. Its position varies depending on the amount of subcutaneous fat present. In a slender individual it lies at the level of L3.
14
Q
What is the intercristal plane?
A
A horizontal line drawn between the highest points of the left and right iliac crests
15
Q
Where and what is McBurney’s point?
A
It is the point 2/3 of the way from the umbilicus to the right anterior superior iliac spine.
- It is the surface marking for the base of the appendix
16
Q
What are the 4 pairs of muscles that comprise the anterolateral abdominal wall and how are their fibres oriented?
A
- External oblique (diagonally oriented)
- Internal oblique (diagonally oriented)
- Transversus abdominis (horizontal)
- Rectus abdominis (straight)
17
Q
What are the 3 muscle layers laying laterally to the rectus abdominis and in which direction are their fibres oriented?
A
- External oblique (Inferomedially)
- Internal oblique (superomedially)
- Transversus abdominis (horizontal)
18
Q
Describe what the rectus abdominis is (3)
What is it attached to superiorly and inferiorly?
A
- The left and right rectus abdominis muscles lie on either side of the linea alba, within the rectus sheath
- It is attached to the sternum and costal margin superiorly and to the pubis inferiorly.
- It is comprised of muscle segments interspersed with horizontal tendinous bands
- When the muscles hypertrophy during exercise, they. bulge and can be seen on the abdominal wall as a ‘6-pack’
19
Q
What arteries supply the anterolateral abdominal wall?
A
- Musculophrenic artery- a branch of the internal thoracic artery
- Superior epigastric artery- continuation of the internal thoracic artery. It descends into the rectus sheath
- Inferior epigastric artery- a branch of the external iliac artery. It ascends in the rectus sheath and anastomoses with the superior epigastric artery (to supply muscles of the abdominal wall)
These vessels are accompanied by deep veins.
20
Q
How is the linea alba formed?
A
- Anteriorly, the 3 layers of muscles become aponeurotic (forming tendons), which fuse with each other at the midline.
- They fuse with aponeuroses from the other side forming a tough midline raph called the linea alba.
Aponeuroses of the muscles also form the rectus sheath enclosing the rectus abdominis.
21
Q
What forms the anterior and posterior layer of the rectus sheath?
A
- The anterior layer of the Internal oblique aponeurosis and the external oblique aponeurosis form the anterior wall of the rectus sheath
- The posterior layer of the internal oblique aponeurosis and the transversus abdominis aponeurosis form the posterior wall of the rectus sheath.
22
Q
What is the inferior part of the external oblique aponeurosis attached to?
A
- The anterior superior iliac spine – laterally
- The pubic tubercle —medially
- The ASIS and pubic tubercle are connected via the inguinal ligament
23
Q
What nerves are the muscles and skin of the anterolateral abdominal wall innervated by?
A
- Thoraco-abdominal nerves T7-T11. Somatic nerves containing sensory and motor fibres.
- Subcostal nerves- originates from T12 spinal nerve.
- Iliohypogastric and ilioinguinal nerves – branches of the L1 spinal nerve.
24
Q
What are the structures that comprise the foregut?
A
- Distal oesophagus
- Stomach
- First half (proximal) of the duodenum
- Liver
- Gallbladder
- Bile duct
- Pancreas
- Spleen
25
What are the structures that comprise the midgut?
- Distal half of the duodenum
- Jejunum
- Ileum
- Caecum
- Appendix
- Ascending colon
- Proximal 2/3 of transverse colon
26
What are the structures that comprise the hindgut?
- Distal 1/3 of the transverse colon
- Descending colon
- Sigmoid colon
- Rectum
27
What is the difference between pain and tendinous?
Tenderness is a sign during examination, pain is a symptom patients say they have
28
Name the organs in the left hypochondriac region
- Stomach
- Pancreas
- Left kidney
- Large intestines
- Spleen
- Liver's tip
29
Name the organs in the epigastric region
- Liver
- Stomach
- Pancreas
30
Name the organs in the right hypochondraic region
- Liver
- Right kidney
- Gallbladder
- Large/small intestines
31
Name the organs in the left lumbar region
- Descending colon
- Small intestine
- Left kidney
32
Name the organs in the umbilical region
- Transverse colon
- Duodenum
33
Name the organs in the right lumbar region
- Right kidney
- Ascending colon
- Small intestine
34
Name the organs in the left iliac region
- Descending colon
- Sigmoid colon
- Small intestine
35
Hypogastric region
- Bladder
- Sigmoid colon
- Small intestine
- Rectum
- Reproductive organs
36
Right iliac region
- Appendix
- Caecum
- Ascending colon
- Small intestine
37
What is the parietal peritoneum and what type of nerve is the parietal peritoneum innervated by?
Can it be seen with the naked eye?
- It is a layer that lines the abdominal wall
It is innervated by somatic nerves that supply the overlying muscles and skin of the abdominal wall
- It can be seen with the naked eye
38
What is the visceral peritoneum and what type of nerve is it innervated by?
Can it be seen with the naked eye?
- It is a layer that covers the abdominal viscera and it cannot be seen with the naked eye
- It is innervated by visceral sensory nerves which conduct 'painful' sensations back to the CNS via sympathetic nerves innervating the organ/structure it covers.
39
What lies in between the parietal and visceral peritoneum and what is its function?
- The peritoneal cavity
- It contains peritoneal fluid which allows the viscera to slide alongside each other
(the 2 layers of peritoneum are continuous with each other)
40
What are the 2 terms used to describe abdominal viscera based on the extent that they are covered by the peritoneum?
What is secondarily retroperitoneal?
Intraperitoneal- Almost completely covered by peritoneum e.g. the stomach
Retroperitoneal- Only covered by peritoneum on their anterior surface as they lie posterior to the peritoneum e.g. the pancreas and abdominal aorta
Secondarily retroperitoneal organs are organs that were intraperitoneal in early development but came to be 'stuck down' into the posterior abdominal wall
41
Name some intraperitoneal organs
Stomach, spleen, liver, jejunum, ileum, transverse colon, sigmoid colon, caecum
42
Name some retroperitoneal organs
abdominal aorta, kidneys, esophagus, pancreas, rectum, parts of the stomach.
43
What action is responsible for the formation of the lesser sac and retroperitoneal organs?
During development, organs grow, migrate and rotate to their final positions. In doing this, they pull their peritoneal attachments with them. This forms the lesser sac and also pushes the organs onto the posterior abdominal wall (thus being retroperitoneal organs)
44
What are mesenteries?
What are embedded in the mesenteries?
- Folds of peritoneum that contain fat.
- They suspend the small intestine and parts of the large intestine from the posterior abdominal wall.
- The arteries that supply the intestines from the abdominal aorta and veins of the portal venous system that drain the gut are embedded in the mesenteries.
45
Describe the greater and lesser omenta
What is embedded within the free edge of the lesser omentum?
- They are folds of peritoneum that are usually fatty.
- They connect the stomach to other organs
- The greater omentum hangs from the greater curvature of the stomach and lies superficial to the small intestine
- The lesser omentum connects the stomach and duodenum to the liver.
- The portal triad is embedded within the free edge of the lesser omentum. (portal triad= hepatic artery, hepatic portal vein and bile duct.
46
What are ligaments?
What is the falciform ligament
What is the ligament that connects the superior surface of the liver to the diaphragm?
- They are folds of peritoneum that connect organs to each other or to the abdominal wall.
- The falciform ligament connects the anterior surface of the liver to the anterior abdominal wall
- The liver connecting the superior surface of the liver to the diaphragm is the coronary and triangular ligaments
47
What is the median umbilical fold?
What is the medial umbiilcal fold?
Peritoneal folds are generally difficult to see
- It is a peritoneal fold that lies in the midline and represents the remnant of the urachus--> an embryological structure connecting the bladder to the umbilicus.
- The medial umbilical fold lies lateral to the median umbilical folds. These are the remnants of the paired umbilical arteries returning venous blood to the placenta (in foetal life)
48
What is the lateral umbilical fold?
It is a peritoneal fold that lies laterally to the medial umbilical folds.
The inferior epigastric arteries lie deep to these peritoneal folds.
49
What are the 2 regions of the peritoneal cavity and how do they communicate with each other? Where are the 2 regions located?
- The smaller sac (omental bursa)- is a space that lies posterior to the stomach and anterior to the pancreas
- The greater is the remaining part of the peritoneal cavity
- They communicate with each other via the epiploic foramen (lies posterior to the free edge of the lesser omentum)
50
What does the GI system develop from?
It develops from the embryonic gut tube which lies in the midline of the abdominal cavity, suspended from the posterior abdominal wall by the dorsal mesentery.
51
What do the major branches of the abdominal aorta supplying the developing gut tube (which becomes the GI system) travel through
The dorsal mesentery
52
What does the ventral mesentery do?
It connects the stomach to the anterior abdominal wall.
- As the liver grows within it, the anterior part of the ventral mesentery becomes the falciform ligament and the posterior part becomes the lesser omentum.
53
Where does the oesophagus pass through the diaphragm? At what level is this?
What is the distal oesophagus continuous with?
The oesophagus passes through the oesophageal hiatus in the diaphragm at the level of T10
It is continuous with the cardia of the stomach
54
What is the term for the muscle around the oesophageal hiatus and what is its function?
The muscle around the hiatus functions as a sphincter that prevents reflux of stomach contents into the oesophagus.
55
What is the distal oesophagus supplied by and where does blood from the distal oesophagus drain into?
- The distal oesophagus is supplied by branches from the left gastric artery.
- Its venous drainage is via both the systemic system of veins (oesophageal veins that drain into azygous veins) and the portal venous system (via the left gastric veins)
This is the site of portosystemic anastomoses.
56
What shape is the stomach and can it expand?
- It is J shaped and it can expand to accommodate food and fluid.
57
What does the stomach break food down into?
The stomach chemically and mechanically breaks down food into chyme.
58
Describe parts of the stomach
- The cardia (which is continuous with the oesophagus)
- The fundus (most superior part of the stomach and is usually filled with gas)
- The body (largest part of the stomach)
- The pyloric antrum (wide and tapers towards the pyloric canal)
- The pyloric canal (narrow and contains the pyloric sphincter which is a circular smooth muscle that regulates the passage of chyme into the duodenum)
- The lesser and greater curvatures of the stomach
59
What does the anterior and posterior surface of the stomach relate to?
Anterior -- anterior abdominal wall, diaphragm and left lobe of liver
Posterior-- anterior wall of lesser sac, pancreas, left kidney and spleen
60
What is the function of the lesser omentum?
- It connects the lesser curvature of the stomach to the liver
- The free edge of the lesser omentum contains the portal triad
- Posterior to the free edge is the entrance to the lesser sac (of the parietal peritoneum)
61
What is the celiac trunk and what does it branch into?
Which of its branches are the smallest in calibre?
- The celiac trunk is a major artery that supplies the foregut of the gastrointestinal tract.
- It arises from the abdominal aorta at the level of T12.
- It branches into the left gastric artery, splenic artery and common hepatic artery
- The left gastric artery is the smallest calibre branch of the celiac trunk
62
Which arteries run alongside the greater and lesser curvature of the stomach?
The gastric arteries run alongside the lesser curvature
The gastro-omental arteries run alongside the greater curvature of the stomach
63
Where do the left and right gastric and gastro-omental arteries arise from?
Left gastric-- branch of the celiac trunk
Right gastric-- branch of the common hepatic artery which is a branch of the celiac trunk
Left gastro-omental- branch of the splenic artery
Right gastro-omental- branch of the gastroduodenal artery, a branch of the common hepatic artery
64
Where do both the gastric and gastro-omental veins drain into? (ultimately)
- They drain ultimately into the hepatic portal vein which carries nutrient-rich venous blood from the GI tract to the liver.
65
What is the stomach innervated by?
What does parasympathetic stimulation promote?
- Parasympathetic fibres are supplied by the vagus nerve -- Parasympathetic stimulation promotes peristalsis and gastric secretion
- Sympathetic fibres are supplied by the greater splanchnic nerves arising from T5-T9 segments of the spinal cord
66
What is the greater splanchnic nerve formed by?
What do they do when they travel to the stomach?
- It is formed by preganglionic sympathetic fibres leaving the spinal cord at the T5-T9 level and they pass through the sympathetic trunk without synapsing
- Instead they synapse in the prevertebral ganglia around the celiac trunk. The postganglionic fibres travel to the stomach and inhibit peristalsis and gastric secretion.
67
What are the 3 parts of the small intestine that are continuous with each other?
Duodenum, jejunum, ileum.
68
Describe the characteristics of the duodenum and is it intraperitoneal or retroperitoneal?
- It is continuous with the pylorus of the stomach
- It is short and curves into a C shape around the head of the pancreas
- Most of the duodenum is retroperitoneal
69
What is the major duodenal papilla and where is it located?
- It is the opening of the bile duct and the main pancreatic duct into the duodenum
- It is located in the duodenum
70
What is the first half and second half of the duodenum developed from and what are they supplied by?
- The first half of the duodenum develops from the embryological foregut and is supplied by arterial branches of the celiac trunk (common hepatic artery)
- The second half of the duodenum develops from the embryological midgut and is supplied by the superior mesenteric artery
71
Describe the location of the jejunum and ileum.
Are they intraperitoneal or retroperitoneal?
What are they derived from?
- The jejunum is located in the left upper region of the small intestine
- The ileum is located in the right lower region of the small intestine
- They are both intraperitoneal and are suspended from the posterior abdominal wall by the mesentery of the small intestine.
- They are both derived from the embryological midgut
72
Where are blood vessels that supply the small intestine (from the superior mesenteric artery) found?
- They are embedded within the mesentery of the small intestine.
73
They jejunum and ileum are sites of nutrient absorption. What characteristics do they have to help them increase surface area to carry out this function? (4)
- The small intestine is long
- The mucosa is folded- plicae circulares
- The mucosal folds bear villi
- There are microvilli on the luminal surface of each epithelial cell (villi)
74
How can you differentiate between the jejunum and ileum?
- The jejunum has more pronounced plicae circulares
- The ileum has Peyer's patches which are large submucosal lymph nodes.
75
What is Meckel's diverticulum? What happens if it becomes inflamed?
- A diverticulum approximately one meter from the ileum's termination
- It is the embryological remnant of the connection between the midgut loop and the yolk sac
- If it becomes inflamed, it may mimic appendicitis.
76
Where is the terminal ileum?
- It is continuous with the caecum at the ileocaecal junction in the right illiac fossa.
77
What is the caecum?
- It is the first part of the large intestine
- It is a distended, blind-end 'pouch'
- It is covered in peritoneum (intraperitoneal) but does not have a mesentery
78
What is the function of the large intestine?
To reabsorb water from faecal material to form semi-solid faeces.
79
What is the large intestine composed of?
Caecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal.
80
What are the characteristics of the large intestine?
The large intestine:
- Is larger in calibre (compared to small intestine)
- The outer longitudinal muscle layer is organised into 3 bands called taeniae coli (facilitates propulsion of gut contents via peristalsis)
- The inner circular muscle later forms 'bulges' called haustra/haustrations (contraction is activated by presence of chyme and it serves to move food slowly to the next haustra.)
- Has fatty tags called epiploic appendages which mark the point where blood vessels penetrate the intestinal wall
81
What is the appendix and how is it connected to the caecum?
- It is a small diverticulum that arises from the caecum containing lymphoid tissue.
- The appendix varies in length and the position of its tip is variable
- It is connected to the caecum via a mesentery- the mesoappendix.
82
Describe the path of the ascending colon.
To what extent is it covered in peritoneum?
- It is continuous with the caecum
- It runs vertically on the right side of the posterior abdominal wall in the right paracolic gutter
- It makes a 90 degree turn left in the upper right quadrants becoming continuous with the transverse colon
- The bend is called the hepatic flexure
- It is retroperitoneal
83
Describe the path of the transverse colon.
To what extent is it covered in peritoneum?
- It is continuous with the ascending colon
- It runs horizontally in the upper abdomen (but hangs inferiorly)
- It is suspended from the posterior abdominal wall by the transverse mesocolon
- The transverse colon makes a 90 degrees turn inferiorly in the left upper quadrant, becoming continuous with the descending colon.
- The bend is called the splenic flexure (tethered to the diaphragm by the phrenicocolic ligament
- It is intraperitoneal
84
Describe the path of the descending colon.
To what extent is it covered in peritoneum?
- It is continuous with the transverse colon superiorly and the sigmoid colon inferiorly
- It runs vertically on the left side of the posterior abdominal wall in the left paracolic gutter
- It is retroperitoneal
85
Describe the path of the sigmoid colon.
To what extent is it covered in peritoneum?
- It has a sinuous shape and lies in the lower left quadrant
- It is continuous with the descending colon superiorly and the rectum inferiorly.
- As it approaches the midline it makes a 90 degree turn inferiorly into the pelvis
- The bend is called the rectosigmoid junction
- The sigmoid colon has a mesentery (the sigmoid mesocolon)--> therefore it is intraperitoneal.
86
Describe the path of the rectum
To what extend is it covered in peritoneum?
What is the function of the rectum?
- It descends inferiorly into the pelvis from the rectosigmoid junction
- It is continuous inferiorly with the anal canal
- It is retroperitoneal
- It stores faeces until it is convenient to defecate.
87
What are the main branches of arteries that the GI tract is supplied by and which parts of the GI tract do they supply?
At what level do these main branches branch of the abdominal aorta?
- The celiac trunk branches off the abdominal aorta at the level of T12 and gives rise to branches that supplies the foregut.
- The superior mesenteric artery branches off the abdominal aorta at the level of L1 and supplies the midgut
- The inferior mesenteric artery branches off the abdominal aorta at the level of L3 and supplies the hindgut
88
What are the major arteries of the superior mesenteric artery and what do they supply?
- Jejunal branches- supplying the jejunum
- Ileal branches- supplying the ileum
- Ileocolic artery- Supplying the caecum, appendix and ascending colon
- Right colic artery- supplying the ascending colon
- Middle colic artery- supplying the transverse colon
Keep in mind that they all form anastomoses with each other
89
The jejunal and ileal arterial branches are embedded in the mesentery of the small intestine. What are formed when they anastomose with each other?
- Loops of arteries called arcades are formed.
- From these arcades run the vasa recta which supply the intestinal wall
90
What are the major arteries of the inferior mesenteric artery?
Left colic artery- supplies the transverse and descending colon
Sigmoid branches- supplies the sigmoid colon
Superior rectal artery- supplies the upper rectum
91
What is the marginal artery?
- It is the artery formed when branches of the middle and left colic artery anastomose along the splenic flexure (and distal third of the transverse colon)
92
What is the path of venous blood drainage from the gut?
- Ultimately, venous blood from the gut enters the liver via the portal venous system where nutrients are absorbed, before being returned to the inferior vena cava.
- The inferior mesenteric vein drains the hindgut and ascends on the left side of the abdomen, draining into the splenic vein coming from the spleen.
- The superior mesenteric vein drains the midgut and it ascends and unites with the splenic vein close to the liver, forming the hepatic portal vein
- The hepatic portal vein enters the liver and after the nutrients are removed from the blood, the blood enters the hepatic veins which unite within the liver to form 2 or 3 large hepatic veins that enter the inferior vena cava (as it passes posterior to the liver)
hepatic veins are within the liver and cannot be seen externally
93
What are the parasympathetic fibres that innervate the foregut, midgut and hindgut?
Where do the parasympathetic fibres supplying the hindgut arise from?
- The foregut and midgut are innervated with parasympathetic fibres from the vagus nerve
- The hindgut is innervated with parasympathetic fibres from the pelvic splanchnic nerves
- The axons of the preganglionic parasympathetic neurons that lie in sacral segments S2-S4 leave the spinal cord to form the pelvic splanchnic nerves
94
What sympathetic fibres are the foregut, midgut and hindgut supplied by and where do they arise from?
Greater splanchnic nerve- arises from T5-T9 -- supplies the foregut
Lesser splanchnic nerve- arises from T10-T11-- supplies the midgut
Least splanchnic nerve- arises from T12 -- supplies the hindgut
95
What does
- Epigastric pain suggest?
- Central abdominal/umbilical pain
- Lower abdominal/suprapubic pain
Why?
- Epigastric pain suggests foregut pathology
- Umbilical pain suggests midgut pathology
- Suprapubic pain suggests hindgut pathology
This is because the regions T5-T12 of the spinal cord also receive somatic sensory information from the abdominal wall. Where Segments T5-T9 receive infromation from dermatomes T5-T9 of the epigastrium, T10-T11 the umbilical region and T12 the suprapubic region
96
Which part of the abdomen is the liver located?
- The right hypochondrium and the epigastrium
96
Where and when may the liver be palpated?
- During inhalation
- The lowermost part of the liver may be palpated below the right costal margin (this is because it moves inferiorly during inhalation and is otherwise protected by the ribs)
97
How are products of digestion apart from lipids transported to the liver?
- Via the hepatic portal vein
98
What is the function of the liver?
- Blood leaving the stomach and intestines passes through the liver where the blood is processed and nutrients are broken down and balanced into forms that are easier for the body to use
- It also stores glycogen and metabolises alcohol and drugs
- It produces bile which is stored in the gallbladder. Bile emulsifies lipids into chyme entering the duodenum.
99
How many surfaces does the liver have and what are they? (what are the surfaces related to)?
- 2 surfaces
- The diaphragmatic surface lies anterosuperior and is related to the inferior surface of the diaphragm
- The visceral surface lies posteroinferior and is related to other organs
100
The liver is mostly covered by peritoneum, however some regions are not covered by peritoneum, which regions are these?
- The bare area of the liver (the region on the posterior surface of the liver that lies in contact with the diaphragm)
- The region where the gallbladder lies in contact with the liver
- The region of the porta hepatis- where hepatic blood vessels and ducts of the biliary system enter and exit the liver (like hilum of the lung)
101
How many lobes does the liver have?
What are the right and left lobes separated by?
- 4 lobes. 2 main lobes (large right lobe and smaller left lobe), 2 accessory lobes (caudate and quadrate)
- The right and left lobes are separated by the falciform ligament (which connects the anterior surface of the liver to the anterior abdominal wall)
102
How many functional segments is the liver organised into?
- Internally, the liver is organised into 8 functional segments, each segment being served by its own branch of the hepatic artery and portal vein, and it own hepatic (bile) duct.
103
What is the liver supplied by?
- It is supplied by the left and right hepatic arteries
Celiac trunk--> common hepatic artery--> hepatic artery proper--> which bifurcates into the left and right hepatic arteries
104
How is the liver drained of venous blood?
- Venous blood exits either by 2 or 3 hepatic veins which unite and drain into the vena cava.
105
What is the difference between the hepatic portal vein and the hepatic veins?
- The Hepatic portal vein transports nutrient rich venous blood leaving the gut to the liver. It is formed when the splenic vein and the superior mesenteric vein unite.
- Hepatic veins transport venous blood leaving the liver to the inferior vena cava
106
What nerves innervate the liver?
Where would pain arising from the liver be referred?
- It is served by the hepatic plexus which is formed by parasympathetic fibres from the vagus nerve and sympathetic fibres.
- As the liver is a foregut derivative, pain arising from it is referred to the epigastric region.
107
How is the liver connected to the diaphragm, the anterior abdominal wall and the stomach + duodenum?
Diaphragm- coronary and triangular ligament
Anterior abdominal wall- falciform ligament
Stomach and duodenum- lesser omentum
108
What does the portal triad consist of and where does it run?
- It consists of the hepatic artery, hepatic portal vein and the bile duct
- It runs in the free edge of the lesser omentum
109
What is the entrance to the lesser sac called and what forms the anterior boundary of the entrance?
- The epiploic foramen is the entrance to the lesser sac
- The portal triad and the free edge of the lesser omentum form the anterior boundary of the epiploic foramen.
110
What are the 2 recesses of the liver and where do they lie?
- The hepatorenal recess- lies between the right kidney and the posterior (visceral) surface of the right side of the liver.
- The left and right subphrenic recesses lie either side of the falciform ligament, between the diaphragmatic surface of the liver and the diaphragm.
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Describe the embryological formation of the liver and the formation of the lesser sac.
- The liver develops from the embryological foregut
- It grows from a tissue bud that develops in the ventral mesentery (connects stomach to anterior abdominal wall)
- As the liver grows and migrates to the right side of the abdomen, its peritoneal attachments are pulled with it
- The remains of the ventral mesentery form the lesser omentum and the falciform ligament.
- Peritoneal attachments of the liver anchor it to surrounding structures including the diaphragm superior to it
112
What is the ligamentum teres? Where is it located and what does it do?
- It is the round ligament of the liver located in the free edge of the falciform ligament.
- It is the embryological remnant of the umbilical vein (carrying oxygenated blood from the placenta to the foetus)
113
What is the ligamentum venosum? Where is it located and what does it do?
- The ligamentum venosum lies on the posterior surface of the liver, in the groove between the caudate and left lobe of the liver.
- It is the embryological remnant of the ductus venosus, which diverts blood from the umbilical vein to the inferior vena cava (shunting oxygenated blood to the heart, bypassing the liver) in the foetus
114
Where does the gallbladder lie and what does it store?
- It lies on the posteroinferior (visceral) surface of the liver
- It stores and concentrates bile (by absorbing water)
115
What are the 3 parts of the gallbladder? explain them more in detail
- The fundus, body and neck
- The fundus is the rounded end of the gallbladder which extends to the inferior border of the liver.
- The body forms the main part of the gallbladder which sits in the gallbladder fossa on the visceral surface of the liver
- The body tapers towards the neck which communicates with the cystic duct
116
What is the surface marking of the fundus of the liver?
- It is at the tip of the 9th costal cartilage, at the point where the right midclavicular line intersects the right costal margin.
117
What is the 'life' of bile from when it is produced in the liver to when it leaves the liver?
- Bile is produced by hepatocytes in the liver and is first excreted into small channels called bile canaliculi
- Bile canaliculi drain into bile ducts of increase calibre, which converges to form the left and right hepatic ducts that exits the liver at the porta hepatis
- The left and right hepatic ducts converge to form the common hepatic duct
- The common hepatic duct receives the cystic duct from the gallbladder and distal to that point is the bile duct (which runs in the free edge of the lesser omentum)
- The bile duct then enters the duodenum
118
What happens when bile is not needed after production and what happens when it is needed?
Where and what is the spiral fold of the gallbladder?
- When bile is not needed for digestion (after production), it enters the gallbladder via the cystic duct
- When needed, bile flows from the gallbladder via the cystic duct to the bile duct and duodenum
- The spiral fold which helps keep the cystic duct open lies at the junction between the gallbladder neck and the cystic duct.
119
What is the gallbladder supplied and drained by?
- It is supplied by the cystic artery, which arises from the right hepatic artery
- It is drained by cystic veins that pass directly into the liver or join the hepatic portal vein
120
What is the gallbladder innervated by? What level do the sympathetic fibres that innervate the liver arise from?
Where is pain felt in the gallbladder referred to?
- It is innervated by both parasympathetic and sympathetic fibres
- Visceral afferents from the gallbladder return to the CNS with sympathetic fibres that arise from T5-T9 spinal cord levels.
- Therefore visceral pain is referred to the epigastrium
121
When will gallbladder pain be referred to the right shoulder? Why?
- If gallbladder pathology irritates the diaphragm.
- As the diaphragm is innervated by the phrenic nerves that arise from C3,4,5 spinal cord segments and Spinal cord segments C3,4,5 also receive somatic sensory information from the skin over the shoulder, gallbladder pathology involving irritation of the diaphragm may be felt in the right shoulder.
122
When will gallbladder pain be referred to the right hypochondrium?
- When gallbladder pathology irritates the parietal peritoneum, which is innervated by somatic nerves.
123
What do the left gastric, splenic and common hepatic arteries supply?
Left gastric- distal oesophagus and lesser curvature of the stomach
Splenic- Spleen, pancreas, stomach
Common hepatic artery- Liver, stomach and duodenum
124
How many parts is the retroperitoneal, C shaped duodenum separated into? What organs are associated with them?
- 4. Superior (first), Descending (second), Inferior (third), ascending (fourth)
- The bile duct, gastroduodenal artery and hepatic portal vein lie posterior to the first part of the duodenum
- The major duodenal papilla (where the bile duct and pancreatic duct drain into the duodenum) is located in the second part
- The superior mesenteric artery lies anterior to the third part
- The fourth part meets the jejunum at the duodenojejunal flexure.
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What is the elevation located halfway along the internal wall of the duodenum and what does it mark?
- The major duodenal papilla marks the point at which bile and digestive pancreatic secretions enter the duodenum.
126
What arterial branches is the duodenum supplied by?
- The proximal half of the duodenum is supplied by the gastroduodenal arteries (a branch of the common hepatic artery)
- The distal half of the duodenum (midgut derivative) is supplied by the inferior pancreaticoduodenal arteries of the superior mesenteric artery.
127
At what level does the pancreas lie horizontally on the posterior abdominal wall?
To what extent is it covered in peritoneum?
How many parts is it divided into and what are they?
- It lies at the level of L1
- It is retroperitoneal
- It is divided into 4 parts. The head, neck, body and tail.
128
What is the pancreas formed from?
- It is formed from the dorsal and ventral pancreatic buds which fuse during development.
129
What is the uncinate process of the pancreas? What occurs there?
- The uncinate process is a hook-like projection of the head of the pancreas.
- This is where the superior mesenteric artery and vein intersect.
130
Where does the tail of the pancreas extend to?
- The hilum of the spleen
131
What forms the border of the lesser sac?
- Anterior border--> stomach
- Posterior border--> pancreas
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Where do the splenic arteries and veins run?
- The splenic artery runs towards the spleen embedded in the upper border of the pancreas.
- The splenic vein lies posterior to the pancreas
133
What are the main functions of the pancreas?
- It synthesises and secretes insulin and glucagon. (insulin being released in response to high levels of glucose in the blood)
- It also produces pancreatic juice that contains digestive enzymes
134
What are the 2 ways that pancreatic juice is transported to the duodenum?
- The main pancreatic duct
- The accessory pancreatic duct
135
Where do the bile duct and main pancreatic duct merge?
Where do they drain into the duodenum?
- They merge at the hepatopancreatic ampulla which opens into the major duodenal papilla in the second part of the duodenum.
136
What is the sphincter of oddi and what is its function?
- It is a layer of smooth muscle surrounding the hepatopancreatic ampulla.
- Contraction of the sphincter of oddi prevents the reflux of duodenal contents into the bile and main pancreatic ducts.
137
Where does the accessory pancreatic duct drain into?
- It empties pancreatic juice into the duodenum at the minor duodenal papilla (lying proximal to the major duodenal papilla)
138
What blood vessels is the pancreas supplied by?
- Splenic artery-- runs along the upper border of the pancreas
- Gastroduodenal artery - gives rise to the superior pancreaticoduodenal arteries
- Superior mesenteric artery- gives rise to the inferior pancreaticoduodenal arteries
139
Where is the hepatic portal vein formed?
- It is formed when the splenic vein unites with the superior mesenteric vein posterior to the neck of the pancreas.
140
Where does the spleen lie? What ribs is it protected by?
What type of peritoneum is it covered by?
What is the function of the spleen?
- The spleen lies in the upper left quadrant, protected by ribs 9-11.
- It is covered by visceral peritoneum
- It is a haematopoietic and lymphoid organ which has several functions: breakdown of old red blood cells, storage of red blood cells and platelets, and various immune responses including production of immunoglobulin G.
141
How many surfaces does the spleen have and what are they?
- It has 2 surfaces.
- The diaphragmatic surface- lies adjacent to the diaphragm
- The visceral surface- lies in contact with the stomach, left kidney and colon.
142
Where do splenic vessels enter and exit the spleen?
- At the hilum of the spleen on the visceral surface
143
How many borders does the spleen have and which are typically notched?
- The spleen has 4 borders
- The anterior and superior borders are typically notched
- The posterior and inferior borders are typically smooth
144
How many times does the spleen have to be enlarged in order to be palpable below the costal margin?
- 3 times
145
How many branches does the splenic artery divide into to supply the spleen?
5
