Basics Flashcards
What spinal levels does the oesophagus stretch across?
C6 (cricoid cartilage) to T11
What is the term given to how food is transported through the GI tract?
Peristalsis
Define peristalsis
Rhythmic contractions of the muscles which propagate food through the GI tract
What forms the upper oesophageal sphincter?
Cricopharyngeus
Where is the lower oesophageal sphincter found?
Gastro-oesophageal junction (left of T11 vertebra)
What causes the 4 constrictions in the oesophageal lumen?
Arch of aorta
Bronchus (left main stem)
Cricoid cartilage
Diaphragmatic hiatus
What letter shape is the stomach?
J-shaped
What are the 4 anatomical divisions of the stomach?
Cardia (T11 level)
Fundus
Body
Pylorus (L1 = pyloric sphincter)
What is the pyloric sphincter made of?
Smooth muscle
Where is the greater omentum found?
Hangs down from the greater curvature of the stomach and folds back up on itself where it attaches to the transverse colon. Can adhere to inflamed areas.
Where is the lesser omentum found?
Continuous with peritoneal layers of the stomach and duodenum. Arises at the lesser curvature and ascends to attach to the liver.
Where does the arterial supply of the stomach come from?
Coeliac trunk:
Lesser curvature -
Right gastric (branch of common hepatic artery arising from coeliac trunk)
Left gastric (arises directly from coeliac trunk
Greater curvature -
Right gastro-omental (terminal branch of gastroduodenal artery, arises from common hepatic artery)
Left gastro-omental (branch of splenic artery, arising from coeliac trunk)
Venous drainage of the stomach?
Right and left gastric veins drain into the hepatic portal vein.
Short gastrin vein, left and right gastro-omental veins drain into the superior mesenteric vein
Parasympathetic supply of stomach?
Anterior and posterior vagal trunks from the vagus nerve
Sympathetic nerve supply of the stomach?
T6-T9 spinal cord segments
Passes to coeliac plexus via greater splanchnic nerve
Carries some pain transmitting fibres
What nodes do gastric lymphatic vessels drain into?
Gastric and omental lymph nodes found at the curvatures
What marks the final part of the small intestine?
Ileocaecal junction (meets large intestine at ileocaecal valve)
3 anatomical parts of the small intestine?
Duodenum
Jejunum
Ileum
How many parts is the duodenum divided up into?
4
Where is the liver connected to the small intestine?
Hepatoduodenal ligament in the first section of the duodenum
What internally marks the descending (second part) of the duodenum?
The major duodenal papilla = opening at which bile and pancreatic secretions enter from the ampulla of Vater (hepatopancreatic ampulla)
What does the inferior part of the duodenum (third part) pass over?
Inferior vena cava and aorta
Where does the duodenum join the jejunum?
Duodenojejunal flexture
What muscle is located at the duodenojejunal junction?
Suspensory muscle of the duodenum
Way to remember the order of the parts of the small intestine?
DJ Ileum
What is a difference between the duodenum and the jejunum+ileum?
Jejunum and ileum are intraperitoneal
How are the jejunum and ileum attached to the posterior abdominal wall?
By mesentery
Where does the ileum end?
Ileocaecal junction
What is found at the ileocaecal junction?
Ileocecal valve
Arterial supply of the duodenum?
Proximal to the major duodenal papilla –> gastroduodenal artery (branch of common hepatic artery from the coeliac trunk)
Distal to the major duodenal papilla –> inferior pancreaticduodenal artery (branch of superior mesenteric artery)
Lymphatic drainage of the duodenum?
Pancreatoduodenal and superior mesenteric nodes
Arterial supply of jejunum and ileum?
Superior mesenteric artery
Venous drainage of the jejunum and ileum?
Superior mesenteric nodes
What is the cecum?
Most proximal part of the large intestine located between the ileum and the ascending colon
Arterial supply to the cecum?
Ileocolic artery - branch of superior mesenteric artery
Venus drainage of cecum?
Ileocolic vein - emptying into the superior mesenteric vein
Lymphatic drainage of the cecum?
Ileocolic lymph nodes
What is the appendix
Narrow blind-ended tube that is attached to the posteromedial end of the cecum
Vascular supply to the appendix?
Superior mesenteric vessels
Sympathetic afferent fibres of the appendix originate…?
T10 of the spinal cord - thus visceral pain is felt centrally within the abdomen in early appendicitis
Lymphatic drainage of the appendix?
Ileocolic lymph nodes
How many parts can the colon be divided into and what are they?
4:
Ascending
Transverse
Descending
Sigmoid
Average length of the colon?
150cm
Where does the transverse colon extend to and from?
From right colic flexure to the spleen
The transverse colon is intraperitoneal. What is it enclosed by?
Transverse mesocolon
What ligament attaches the colon to the diaphragm?
Phrenicocolic ligament
What spinal levels does the sigmoid colon extend over?
Left iliac fossa to S3
What attaches the sigmoid colon to the posterior pelvic wall?
Mesentery = sigmoid mesocolon
What are the small pouches of peritoneum, filled with fat, that are attached to the surface of the colon?
Omental appendices
What are the 3 trips of muscles running longitudinally along the surface of the colon called?
Teniae coli
What makes up the teniae coli?
Mesocolic, free and omental coli
What are the sacculations produced by teniae coli contractions called?
Hausta
Midgut structures?
Distal half of the duodenum, jejunum, ileum, cecum, ascending colon and proximal 2/3 of transverse colon.
Hindgut structures?
Distal 1/3 of transverse colon, descending colon and sigmoid colon, proximal 3rd of the rectum
Foregut structures?
Distal end of oesophagus, stomach, proximal part of duodenum, pancreas, liver gallbladder.
What is the arterial supply of mid-gut derived structures?
Superior mesenteric artery
What is the arterial supply of hind-gut derived structures?
Inferior mesenteric artery
What is the arterial supply of the foregut?
Celiac artery
Innervation of foregut?
Vagus nerve
Innervation of midgut?
Vagus nerve, and lesser splanchnic nerve
Innervation of hindgut
Inferior mesenteric plexus
(L1-L2 = sympathetic lumbar splanchnic nerves)
(S2-S4 = parasympathetic innervation)
Arterial supply of ascending colon?
Ileocolic and right colic arteries from the superior mesenteric artery
Transverse colon arterial supply?
Right colic artery from SMA
Middle colic artery from SMA
Left colic artery from LMA
Descending colon arterial supply?
Left colic artery from inferior mesenteric artery
Sigmoid colon arterial supply?
Sigmoid arteries = branches of IMA
Why is the Marginal Artery of Drummond important?
Provides collateral supply to the colon
Venous drainage of the ascending colon?
Ileocolic and right colic veins –> SMV
Venous drainage of the transverse colon?
Middle colic vein –> SMV
Venous drainage of the descending colon?
Left colic vein –> IMV
Venous drainage of sigmoid colon?
Sigmoid veins –> IMV
Where do the superior mesenteric veins and inferior mesenteric veins empty into?
Hepatic portal vein
Where does the rectum terminate into?
Anal canal
What spinal level does the rectum begin?
S3
What is the anorectal flexture?
Anteroposterior curve (with convexity anteriorly) of the rectum formed by the tone of the puborectalis muscle
What is the sacral flexture?
Anteroposterior curve (with concavity anteriorly) following the curve of the sacrum and coccyx
What is the final section of the rectum called?
Ampulla
What part of the rectum is covered anteriorly and laterally by peritoneum?
Superior 3rd of rectum
What part of the rectum is only covered anteriorly by peritoneal?
Middle 3rd of rectum
Arterial supply to the rectum?
Superior rectal artery –> IMA
Middle rectal artery –> internal iliac artery
Inferior rectal artery –> internal pudendal artery
Venous drainage of the rectum?
Superior, middle and inferior rectal veins
Superior rectal vein –> portal venous system
Middle and inferior rectal veins –> systemic venous system
Sympathetic nerve supply of the rectum?
Lumbar splanchnic nerves
Superior and inferior hypogastric plexuses
Parasympathetic nerve supply of the rectum?
S2-S4 via the pelvic splanchnic nerves and inferior hypogastric plexuses
Lymphatic drainage of rectum?
Pararectal lymph nodes –> inferior mesenteric nodes
Lymph from lower aspect of rectum drains directly into internal iliac lymph nodes
What makes up the internal anal spinchter?
Thickening of involuntary circular smooth muscle surrounding the supper 2/3 of the anal canal
What makes up the external anal spinchter?
Voluntary muscle that surrounds the lower 2/3 of the anal canal. Blends superiorly with the puborectalis muscle of the pelvic floor.
What makes up the anorectal ring?
Anal canal, internal anal sphincter, external anal sphincter, puborectalis muscle
What is the pectinate line?
Where the internal and external anal sphincters form an irregular circle
Above the pectinate line in the anus - embryonic orgination?
Hindgut
Below the pectinate line in the anus - embryonic orgination?
Ectoderm of the proctodeum
Arterial supply superior to pectinate line?
Superior rectal artery (branch of IMA)
Anastomosing branches from middle rectal artery
Arterial supply posterior to pectinate line?
Inferior rectal artery (branch of internal pudendal artery)
Anastomosing branches from the middle rectal artery
Venous drainage from above the pectinate line?
Superior rectal vein (empties into IMA –> portal venous system)
Venous drainage from below the pectinate line?
Inferior rectal vein (empties into internal pudendal vein –> systemic venous system)
Innervation above the pectinate line?
Visceral innervation via the inferior hypogastric plexus.
Sensitive to stretch.
Innervation below the pectinate line?
Somatic innervation via the inferior rectal nerves (branches of pudendal nerves)
Sensitive to pain, temperature, touch and pressure
Lymphatic drainage above the pectinate line?
Internal iliac lymph nodes
Lymphatic drainage below the pectinate line?
Superficial inguinal lymph nodes
