The GI Tract Flashcards
At what vertebral level does the oesophagus cross the diapghram?
T10
What other structures pass through the oesophageal opening?
1) Vagus nerve
2) Left inferior phrenic vessels
3) Left gastric artery
What is the blood supply of the abdominal oesohagus?
Left gastric artery and left inferior phrenic artery
What is the venous drainage of the abdominal oesophagus?
Drainage to:
Portal venous system - Left gastric artery
Systemic circulation - Azygos vein
These 2 drainage routes form an anastamosis between the portal and systemic venous systems
What is the lymphatic drainage of the abdominal oesophagus?
Upper 1/3 - Deep cervical lymph nodes
Middle 1/3 - Superior + posterior mediastinal nodes
Lower 1/3 - Left gastric + coeliac nodes
What are the 2 orifices of the stomach?
Pyloric sphincter
Lower oesophageal sphincter
What are the 2 curvatures of the stomach called?
Lesser and greater
What are the 2 surfaces of the stomach called?
Anterior and posterior
What is the pyloric sphincter?
Strong ring of smooth muscle
What is the function of the pyloric sphincter?
It controls the exit of chyme from the stomach into the duodenum
From which layer of the gut tube is the pyloric sphincter formed?
Muscularis externa
What are the ruage of the stomach formed from?
Mucosa
Which structures does the stomach lie upon?
- Body of pancreas
- Spleen
- Colon
Into which group of lymph nodes do the gastric lymphatics drain?
Pre-aortic
Stimulation of the vagus nerve will do what to pyloric sphincter and gastric secretion?
Pyloric sphincter - will be relaxed
Gastric secretion - will be increased
Which part of the small intestien receives bile and the opening of the pancreatic duct?
Duodenum
How is the small intestine peritonised?
Duodenum - retroperitonised
Jejunum - Intraperitoneal
Ileum - Intraperitoneal
How can the jejunum and ileum be differentiated?
Jejunum - Red, thick, long & straight vasa recta, few arcades, less fat in mesentery
Ileum - Paler pink, thin, short vasa recta, many short loops of arcades, more fat in mesentery
Jejunum on left, Ileum on right
What features differentiate the large intestine from the small intestine?
1) Larger diameter
2) Omental appendices (fat filled pouches)
3) Teniae Coli (3 strips of muscle)
4) When the Teniae Coli contract they form small saccules called Haustra
How is the large intestine peritonised?
Caecum - Intraperitoneal
Ascending colon - Retroperitoneal
Transverse colon - Intraperitoneal
Descending colon - Retroperitoneal
Sigmoid colon - Intraperitoneal
What 2 structures open into the caecum?
1) Ileum
2) Appendix
What is McBurney’s point and why is it useful?
A point on the RHS of the abdomen which is 1/3 of the distance from ASIS to the Umbilicus
This point is the most common location of the base of the Appendix
What is the arterial supply, venous drainage and peritonisation of the superior 1/3 of the rectum?
Arterial supply - Superior rectal artery
Venous drainage - Superior rectal vein
Peritonisation - Retroperitoneal
What is the arterial supply, venous drainage and peritonisation of the middle 1/3 of the rectum?
Arterial supply - Middle rectal artery
Venous drainage - Middle rectal vein
Peritonisation - Anterior
What is the arterial supply, venous drainage and peritonisation of the inferior 1/3 of the rectum?
Arterial supply - Inferior rectal artery
Venous drainage - Inferior rectal vein
Peritonisation - None
What is the role of the pelvic floor in maintaining faecal continence?
Helps maintain intra-abdominal pressure
What structures are involved in faecal continence?
Anal canal
Rectum
What ligaments are part of the lesser omentum?
Hepatoduodenal and hepatogastric ligaments
What is the falciform ligament and what structures lie within its free border?
The falciform ligament attaches the liver the anterior body wall
Within the free border of the falciform ligament are the round ligament and paraumbilical veins
What structure within the free edge of the falciform ligament is remnant of an embryonic blood vessel?
Paraumbilical vein - Umbilical vein in embryo
How many layers of peritoneum are present in the Greater Omentum?
4 layers of visceral peritoneum
What are paracolic gutters?
Spaces between colon and abdominal wall
These spaces are important as they can allow infected fluids to travel between abdominal regions
Where are the paracolic gutters found?
They are found alongside the ascending and descending colon
What muscle types form the muscularis externa of the GI tract?
Skeletal and smooth
What secretory cells are found within gastric pits?
Parietal and chief cells
What are the histological features of the stomach?
Rugae
Chief cells
Parietal cells
Gastric pits
What are the histological features of the small intestine?
Plicae circularis
Microvilli
Where in the gut tube do glands extend down below the muscularis mucosa?
Oesophagus & duodenum
What 2 horizontal lines help to divide the stomach into 9 regions?
Transpyloric plane
Transtubercular plane
What structures does the transpyloric plane pass through?
Pylorus of stomach
Gallbladder
Pancreas
Kidneys
Spleen
