GI and Liver Anatomy Flashcards
rectus abdominus
6 pack muscles
paired long muscles from sternum to pubis symphosis
surrounded by rectus sheath which is aponeuroses
‘tendinous intersections’ traverse them it and seperate them into distinct bellies
other abdominal muscles
- external oblique
- lateral to rectus abdominis
- runs downwards and inwards
- interdigitates with serratus anterior above it
- Internal oblique
- deep to the external obliques
- runs upwards and inwards
- Transverse abdominis
- deepest abdominal muscle
- Aponeurosis from these muscles wraps around the rectus abdominus and forms the rectus sheath
bony landmarks that define the boundaries of the abdomen
- Xiphisternum
- Costal margin
- Iliac crest
- Anterior superior iliac spine
- Pubic tubercle
- Pubic symphysis
9 abdominal regions and the boundaries of the lines
- verticle lines on both sides extend from the mid clavicular point to the mid-inguinal point
- the mid inguinal point is half way between the piubis symphysis and the anterior superior iliac spine
- the upper horizontal line is the subcostal plane
- this joins the costal margins on both sides
- the lower horizontal line is between the tubercles of the iliac crests
Mcburney’s point
- 2/3 of the way from the umbilicus to the right anterior superior iliac spine
- marks site of base of appendix
- gives a guide to the position of the caecum during clinical examination of the abdomen
transpyloric plane of addison
- lies roughly a hands breadth below the xiphisternum
- it crosses the epigastrum at the level that the midclavicular line crosses the costal margin
- structures that lie on this plane:
- gall bladder
- pancreas
- pylorus of the stomach
- duodenal-jejunal flexure
to which vertebra does the umbilicus correspond (only in a thin recumbent patient)
L3
intertubercular plane
- imaginary line between the two tubercles of the iliac crests
- it marks the position of the bifurcation of the abdominal aorta
- e.g. an aortic aneurism would only be felt above this poin t
what nerve supplies the foregut
- the greater splanchnic nerve (T5-T9)
- pain from the foregut is felt at the epigastrum
what nerve supplies the midgut
- the lesser splanchnic nerve
- T10-T11
- pain referred to the periumbilical area
what nerve supplies the hindgut
- Lowest splanchnic nerve
- T12
- pain is referred to the suprapubic area
pain of the peritoneum
- peritoneum has the same nerve supply as the skin
- disease that involves the gut wall is felt directly over where the cause of the pain is
what is the nerve supply to the diaphragm?
- the phrenic nerve
- C3, C4 and C5
- diseases that irritate the diaphragm are felt in the shoulder
sensory innervation of the kidney
- kidney and gonads are both supplied by the T10-T12 sympathetic plexus
- loin to groin referred pain for both areas
what is the T10 dermatome
the level of the umbilicus
what is the upper extent of the abdominal cavity?
- the under surface of the diaphragm reaches the 5th intercostal space
in what regions of the abdomen is the pain of the foregut, midgut and hindgut felt?
- foregut: epigastrium
- midgut: umbilical
- hindgut: suprapubic
describe the histology of the peritoneum
simple squamous epithelium
layers of peritoneum
- where it covers the abdominal wall: parietal peritoneum
- where it covers the viscera: visceral peritoneum
space between the two layers is the peritoneal cavity
linea alba
- fibrous structure that runs down the midline and seperates the rectus abdominus muscles
left triangular ligament
- to the left of the falciform ligament is the left lobe of the liver
- the peritoneum meets the falciform ligament and travels down it to become thee visceral peritoneum on the surface of the liver
- the left lobe of the liver attaches to the under surface of the diaphragm via a double layer of peritoneum called the left triangular ligament
the lesser omentum
- extends from the diaphragm down to the porta hepatis on one side and the duodenum on the other
- porta hepatis is where the portal vein and the hepatic artery enter the liver and where the bile duct leaves
- it is attached to the lesser curvature of the stomach
- the portal triad runs in the free edge of the lesser omentum
- behind this free edge where they run is the epiploic foramen (of winslow)
- the only way from the main peritoneal cavity into the lesser sac is through this foramen
spleen
well above the costal margin and can not usually be palpated
the greater omentum
- comes off greater curvature of the stomach
- has transverse colon attached to its deep surface
artery to the foregut, venous drainage and innervation
- the coeliac trunk
- branches from aorta just below diaphragm
- supplies
- lower third of the oesophagus until the 2nd part of the duodenum
- liver
- pancreas
- venous drainage is into the portal vein
- innervation is by the greater splanchnic nerve (T5-9)
- there’s parasympathetic innervation from the vagus
rugae
the folds on the inside of the stomach
which structures pass through the diaphragm with the oesophagus
the vagal trunks, the inferior oesophageal artery and vein
from where does the stomach recieve its nerve supply
Parasympathetic: vagus
sympathetic: greater splanchnic T5-T9
the coeliac trunk
after emerging from the aorta the coeliac trunk extends approximately 1cm before dividing into three major branches
- the splenic artery
- the common hepatic artery
- the left gastric artery
Splenic artery
- travels left to the spleen posteriorly to the stomach
- travels on the superior margin of the pancreas
- gives rise to the left gastro-epiploic
- this supplies the greater curvature of the stomach
- it anastomoses with the right gastroepiploic
- Pancreatic branches
- these supply the body and tail of the pancreas
- Short gastrics
- 5-7 small branches that supply the fundus of the stomach
left gastric artery
- this is the shortest branch off the coeliac trunk
- gives rise to oesophageal branches
- supplies the lesser curvature of the stomach
Gastroduodenal artery
- arises from common hepatic artery
- gives rise to:
- right gastroepiploic - greater curve of the stomach
- superior pancreatoduodenal - head of pancreas
plicae circulares
- folds in the mucosa of the small bowel
- these are more pronounced in the jejunum than the ileum
artery to the midgut
- this is the superior mesenteric artery
- it branches from the aorta just below the coeliac trunk
- supplies from the 3rd part of the duodenum to 2/3rds along the transverse colon
peyer’s patches
large sub-mucosal lymph nodules in the ileum
fat distribution in the small bowel mesentry
there’s more towards the ileal end
which parts of the bowel are on a mesentary?
- duodenum is mostly retroperitoneal
- jejunum and ileum are on a mesentry and are relatively mobile
- ascending colon is retroperitoneal
- transverse colon is on a mesentry
- the descending colon is retroperitoneal
- the sigmoid colon is on a mesentry
what are the longitudinal muscles in the large bowel called?
- the taeniae coli - there are three of them
- they start at the base of the appendix and go to the recto-sigmoid junction
- they contract lengthwise producing the characteristic haustrations
the hind gut
- this extends from the distal third of the transverse colon to one third of the way down the anal canal
- supplied by the inferior mesenteric artery
- arises from the lower aorta just above the bifurcation
where does lymph from the small bowel drain?
- it drains into the cisterna chyli and into the thoracic duct
4 anatomical features that ensure the small bowel has a high surface area for absorption of nutrients
- length
- mucosal folds (plicae circularis)
- villi
- microvilli
describe the journey of bile from the liver and where it goes
NB sphincter of oddi is in the ampulla of vater
label this liver
Label this liver
ligamentum venosum
- this is the remnant of the ductus venosus
- it’s attached to the left branch of the portal vein within the porta hepatis and stretches up to the IVC
- so blood would have come in the umbilical vein (ligamentum teres) and bypassed the liver by passing up the ductus venosus (ligamentum venosum) on the posterior side of the liver and entering the IVC
where can gall bladder disease sometimes present with pain
- fundus of gall bladder lies underneith the diaphragm
- disease of the gall bladder may cause rubbing on the diaphragm
- pain in the diaphragm is carried by the phrenic nerve so may present as pain in the right shoulder
what arteries does the coeliac trunk give rise to and what do these arteries supply?
- Left Gastric Artery
- lesser curvature of the stomach
- the lower 3rd of oesophagus
- Common Hepatic Artery
- liver
- gall bladder
- stomach
- duodenum
- pancreas
- Splenic Artery
- pancreas
- stomach
- spleen
how much of the duodenum is on an omentum and how much is retroperitoneal
most of it is retroperitoneal and only the first part is on the lesser omentum
label these arteries
what is calot’s triangle?
where does the coeliac trunk come off the aorta?
at T12
hepatic portal vein is formed by?
- splenic vein
- superior mesenteric vein (from small intestine)
- inferior mesenteric vein (from large intestine)
venous drainage through the liver
draw a hepatic lobule
- cells
- kupffer cells
- hepatocytes
- ito cells
- store vitamin A
- bile caniculi
- sinusoids
- fenestrations allow easy movements of proteins
what is the space of disse?
- the space between the hepatocytes and the sinusoids
- allows the absorbtion of plasma by the hepatocytes
- lymph flows through here ending in the cisterna chyli and the thoracic duct
- thoracic duct drains into the left brachiocephalic vein
zones of the liver acinus
which part of the duodenum is bile secreted into?
the 2nd part
histology of the gall bladder
simple columnar epithelium
parts of the pancreas
where is the inguinal ligament
- between ASIS and the pubis symphysis
T4 dermatome
level of the nipples
T6 dermatome
level of the xiphisternum
T10 dermotome
level of the umbilicus
L1 dermotome
immediately suprapubic region
every layer from skin to the abdominal organs
- skin
- subcutaneous fat
- camper’s fascia (superficial and fatty)
- scarpa’s fascia (deep and fibrous)
- abdominal muscles
- rectus abdominus & sheath medially
- ext & int obliques and transversalis abdominis
- transversalis fascia
- extraperitoneal fat
- parietal peritoneum
- peritoneal cavity
- visceral peritoneum
- intraperitoneal organs
what are the five stages of gut development
- Elongation
- Herniation
- Rotation
- Retraction
- Fixation
what is Killian’s Dehiscence
- a weak sitw in the posterior pharyngeal wall between constrictor muscles that is a common site for phargyngeal diverticulum
where are the palatine tonsils
in the oropharynx
name two things that are in the nasopharynx
- adenoids
- eustachian tube
What are haustra
- they are formed by 3 seperate longitudinal muscles called taenia coli
- these muscles contract along the length of the entire colon
- haustra are the bulges formed due to this
how can you tell the difference between the jejunum and the ileum
- the jejunum is:
- smaller
- thicker
- redder
- has more plicae circularis
- has fewer arcades with longer infrequent branches
- ileum has more arcades with numerous shorter branches
Brunner’s glands
- present in the duodenum
- secrete alkaline mucous rich in bicarbonate
- this is to:
- inactivate pepsin
- protect the duodenal mucosa from acid damage
- lubricate the intestinal wall
paneth cells
- lie at the very bottom of crypts of lieberkuhn below stem cell
- secrete anti-microbial compounds
Meckel’s diverticulum
- a vestigial remnant of the vitelline duct
- 2% of people have it
- it’s normally asymptomatic but they can get diverticulitis
why might liver failure lead to ascites
lack of albumin production causes drop it oncotic pressure and blood leaves the vessels
at what level is the transpyloric plane?
L1
