APC1 Flashcards
What is the course of the oesophagus?
Begins C6, continuous with laryngopharynx
Lies in superior and posterior mediastina
Enters abdomen at T10 through muscular part of diaphragm (left of midline) - sling of muscle originating from right crus encircles oesophagus at this point
Short intra-abdominal course before entering stomach
What structures is oesophagus related to?
Anteriorly - the posterior surface of the liver
Posteriorly - left crus of the diaphragm
Closely related to descending aorta – first on its right side, and then in front of it.
Enters thorax slightly left of median plane, more left as it descends - around T7, begins to pass from medial side of descending aorta to front of it;
Oesophagus even more left than the aorta before it pierces the diaphragm.
What contributes to the sphincteric action of the oesophago-gastric junction?
Sling of muscle from right crus
Short intra-abdominal course
Tone in smooth muscle of oesophageal wall
Flap of mucous membrane where oesophagus and stomach meet
Folds of mucous membrane at lower end of oesophagus
What is the blood supply of the oesophagus?
Upper third: inferior thyroid artery and veins, deep cervical nodes
Middle third: branches from thoracic aorta, azygos system, superior and posterior mediastinal nodes
Lower third: branches from left gastric artery, left gastric vein (tributary of portal vein), nodes along left gastric artery –> coeliac nodes at origin of celiac artery
Where are the constrictions of the oesophagus?
Through cricopharyngeus
Posterior to arch of aorta and left primary bronchus
Through the diaphragm
These are sites where foreign bodies can lodge, and can be difficult to pass esophagoscope
Strictures form here after drinking caustic substances as delay in moving substances
What is the nerve supply of the oesophagus?
Sympathetic: sympathetic trunk and splanchnic nerves
Parasympathetic: vagus nerves branch and contribute to oesophageal plexus on its anterior surface
Left vagus nerve becomes anterior vagal trunk, right vagus nerve becomes posterior vagal trunk
Recurrent laryngeal nerves (branches from the vagus nerve) supply upper part of oesophagus
What does the abdominopelvic cavity consist of?
Abdomen proper and pelvic cavity
Continuous at pelvic inlet
How is the abdomen divided into 9 regions?
Upper horizontal plane: TRANSPYLORIC
(1/2 between jugular notch and upper border pubic symphsis, lower border L1)
or SUBCOSTAL
(10th costal margin + L3 body)
Lower horizontal = TRANSTUBERCULAR
(L5, through iliac tubercles)
Vertical = MIDCLAVICULAR
(mid clavicle –> midway between ASIS and pubic tubercle)
Where does large intestine lie?
Ascending colon: lies on PAW mainly in right lumbar region
Descending colon: similar position, left lumbar
Transverse: suspended from PAW via peritoneum, traverses abdomen - hangs down into umbilical region or even lower
Sigmoid: left iliac region (fossa) and hypogastric region
Where do the liver, spleen and pancreas lie?
Liver: right hypochondrium, epigastric, part of left hypochondrium
Spleen: left hypochondrium beneath left dome of diaphragm - outer convex surface is separated from the posterior parts of the 9-11th ribs by the diaphragm and costodiaphragmatic recess of the pleural cavity
Pancreas: within C loop of duodenum and lies with axis directed from right to left, towards spleen
What is the greater omentum?
Large, apron-like fatty fold lies anterior to small intestines, ultimately attached to PAW
Transverse colon attached to posterior surface
What is the duodenojejunal flexure?
Point where small intestine disappears behind PAW (follow it all the way up) - where C shape of duodenum becomes jejunum (retroperitoneal duodenum –> intraperitoneal jejunum)
Jejenum comes forward as is wrapped in peritoneum
What is the name of the junction between small and large intestine?
Ileocaecal junction
What is the caecum?
Right iliac region - dilated portion of large intestine
Vermiform appendix near its apex
What is the right colic flexure?
Hepatic flexure
Point where: ascending colon (right lumbar region) becomes is continuous with transverse colon
Right colic (hepatic) flexure
adjacent to liver
right kidney lies posteriorly
What us the left colic flexure?
Splenic flexure
Transverse colon becomes continuous with descending colon
What are retroperitoneal organs?
S: suprarenal (adrenal) gland A: aorta/IVC D: duodenum (second and third part) P: pancreas (except tail) U: ureters C: colon (ascending and descending - not caecum) K: kidneys E: (o)esophagus R: rectum
What is the peritoneum?
Peritoneal cavity?
Serous membrane, lines walls of APC and invests abdominopelvic organs
Cavity: space between adjacent serous surfaces of peritoneum (doesn’t contain organs) &contains small amount of peritoneal fluid
- closed sac in male
- in female - open to exterior due to arrangement of ovaries and fallopian tubes
What is peritoneal fluid?
Small volume of fluid within peritoneal cavity derived from tissue fluid (therefore plasma)
Fairly rapid turnover of fluid which is absorbed by peritoneal cells
Provides lubrication so that mobile abdominal viscera may move freely
What is the dorsal mesogastrium?
Double layer of peritoneum - suspends gut tube from posterior wall in the embryo
Stomach, small intestine and parts of large intestine retain this
Adult: completely invested by peritoneum and suspended away from the posterior abdominal wall by double layer of peritoneum
What occurs in the duodenum, ascending and descending and colon and rectum? (peritoneum)
They come to lie in contact with PAW, double layer of peritoneum is wholly or partially absorbed, leaving viscera with coating of peritoneum on their anterior or anterolateral surfaces only
Lower part of rectum and whole anal canal have no peritoneum associated
What is the ventral mesogastrium?
Double layer of peritoneum derived from septum transversum (caudal foregut [stomach] region of embryo possess this)
Dorsal mesogastrium reflected on to PAW, ventral reflected onto AAW - stomach therefore completely suspended by peritoneum between the anterior and posterior walls
Where do the spleen and liver develop?
Spleen: dorsal mesogastrium
Liver: vetral mesogastrium
What are lines of peritoneal reflection?
Points at which double layers spread out to become continuous with parietal peritoneum
Where is the stomach situated?
Empty - left hypochonrdium and epigastrium
Varies in size, shape, position depending on volume of contents and posture and physique of individual
Lies partly undercover of lower left ribs
What are the two relatively fixed parts of the stomach?
Cardiac orifice - inferior to diaphragm where oesophagus joined
Pyloric orifice - stomach continuous with duodenum, to right of midline at L1
What are the curvatures of the stomach?
Lesser: cardiac orifice –> pylorus
Angular notch on lowest part of lesser curvature (incisura angularis) - permanent feature of the stomach
Greater: left of cardiac orifice –> over dome of fundus –> inferior part of pylorus
What are the parts that the stomach is divided into?
Fundus: dome-shaped above cardiac orifice level (projects superiorly and left, below left dome of diaphragm) - in upright position usually full of gas -> X-ray identification
Body: cardiac orifice level –> angular notch level
Pyloric part =
- proximal pyloric antrum
- distal tubular pyloric canal or pylorus - surrounded by thick layer of circular smooth muscle - pyloric sphincter
Describe peritoneum of the stomach (derivatives)
Continuous with derivatives of the ventral and dorsal mesogastria (embryonic mesenteries attach caudal foregut to anterior wall and PAW)
1) Part of VENTRAL mesogastrium which extended between lesser curvature and liver develops into LESSER OMENTUM
2) Part extended between liver and AAW develops into FALCIFORM LIGAMENT
3) DORSAL mesogastrium has three derivatives: greater omentum, GASTROSPLENIC ligament (greater curvature –> spleen) and LIENORENAL ligament (spleen —> PAW)
What are rugae?
Numerous folds in the interior of the stomach - occur due to folding of mucous membrane and underlying submucosa
In life, mucous membrane is very vascular
Four or five constant longitudinal rugae are normally present along the lesser curvature of the stomach
Rugae seen elsewhere in stomach usually flatten out when stomach is distended
What is the blood supply of the stomach derived from?
Celiac artery (artery of embryonic foregut, short, arises immediately below diaphragm at T12)
Three branches: left gastric, splenic, common hepatic
What is the left gastric artery?
Passes superiorly and left, across the PAW, to point where peritoneum is reflected from inferior surface of diaphragm on to oesophagus
Gives branches to lower third of oesophagus
Descends along lesser curvature, between layers of lesser omentum: supplies anterior & posterior surfaces of stomach by small branches
What is the splenic artery?
Tortuous course across posterior abdominal wall to supply spleen (passes between two layers of lienorenal ligament)
Runs along top of pancreas and supplies it
After supplying spleen at hilum –> SHORT GASTRIC arteries and LEFT GASTROEPIPLOIC artery
Short gastric arteries: supply fundus via gastrosplenic ligament
Left gastroepiploic: along greater curvature (between two layers of greater omentum) - supplies anterior and posterior surfaces of stomach and GREATER OMENTUM by small branches
What is the common hepatic artery?
Three branches: hepatic artery proper (supplying liver), RIGHT GASTRIC artery and GASTRODUODENAL artery
Right gastric: between two layers of lesser omentum and ascends along lesser curvature to supply anterior and posterior surfaces by small branches - anastomoses with left gastric artery
Gastroduodenal artery: passes posterior to superior (first) part of duodenum and gives rise to RIGHT GASTROEPIPLOIC and SUPERIOR PANCREATICODUODENAL arteries
What are the branches of the gastroduodenal artery?
Right gastroepilploic: passes along greater curvature between two layers of greater omentum, supplying anterior and posterior surfaces of stomach and greater omentum by small branches - anastomoses with left gastroepiploic artery
Superior pancreaticoduodenal: supplies head of pancreas and foregut region of duodenum (midgut part = superior mesenteric)
Which arteries gain access to intraperitoneal stomach by using the retroperitoneal region of the duodenum as an entrance, then passing between layers of peritoneum (the omenta)
Right gastric
Right gastroepiploic
What is the venous and lymphatic drainage of the stomach?
Venous via veins accompanying corresponding arteries –> directly into hepatic portal vein OR via one of its tributaries
Four main groups of lymph nodes: LEFT GASTRIC, PYLORIC, PANCREATICOSPLENIC, RIGHT GASTROEPIPLOIC
Lymph vessels runs with arteries of the stomach and drainage pattern similar to arterial distribution (but obviously flowing in other direction)
All lymph eventually drains to celiac nodes around origin of celiac artery (as stomach = foregut structure)
What is the sympathetic supply of the stomach? What is its function?
Fibres arise from segments T6-T9 and pass through diaphragm as the greater splanchnic nerves
Synapse in celiac ganglia, within the celiac plexus
Post-ganglionic fibres pass with blood vessels to stomach
Efferents vasoconstict the gastric blood vessels, inhibit gastric musculature and secretory glands, stimulate the pyloric sphincter
Afferent autonomic fibres primarily concered with pain travel with sympathetic pathways
What is the parasympathetic supply of the stomach? What is its function?
Left and right vagus nerves become anterior and posterior vagal trunks as they pass through the diaphragm to supply stomach
Anterior trunk and posterior trunk supplies anterior and posterior surface of stomach by number of smaller branches
- Some branches contribute to the celiac plexus (prevertebral autonomic plexus found at origin of celiac artery)
Vagal fibres stimulate gastric secretion, contraction of gastric musculature, relaxation of the pyloric sphincter
Hepatic branches derived from both vagal trunks and pass between layers of lesser omentum to join hepatic plexus
Afferent fibres travelling within the vagus concerned with reflex activity in response to mechanical and metabolic stimuli
Describe stomach surface anatomy
Cardiac orifice behind 7th costal cartilage (left of midline)
Pyloric orifice on transpyloric plane (right of midline)
Highest point of fundus = 5th intercostal space
Greater curvature extends downwards and left as fat as 10th costal cartilage, before turning medially to reach pylorus
Lowest part of the curving path of lesser curvature marked by angular notch (incisura angularis), which lies just left of the midline
Where does the duodenum lie?
Commences at pyloroduodenal junction to right of midline at about L1 - lies in epigastric and umbilical regions
Mostly retroperitoneal therefore relatively fixed in position
In direct contact with PAW
What is the first part of the duodenum? What is it in contact with?
1st = Superior part
Starts at pylorus and passes posterosuperiorly to right under cover of the liver and gallbladder
Proximal portion not retroperitoneal but enclosed by lesser omentum
Remainder is retroperitoneal
Bile duct, gastroduodenal artery and hepatic portal vein pass behind the retroperitoneal portion
What is the second part of the duodenum? What is it in contact with?
2nd = descending
Arches around head of pancreas
Entirely retroperitoneal and separated by loose CT from the fat and fascia covering the hilar region of the right kidney
BILE duct opens with MAIN PANCREATIC duct into posteromedial aspect, at MAJOR DUODENAL PAPILLA - marks the junction between embryonic foregut and MIDGUT
Sometimes an accessory pancreatic duct opens into the duodenum proximal to the major papilla at the MINOR PAPILLA
What is the third part of the duodenum? What is it in contact with?
3rd = horiztonal
Completely retroperitoneal
Passess transversely across PAW at about L3
Superior mesenteric vessels cross anterior surface
What is the fourth part of the duodenum? What is it in contact with?
4th = ascending
Passess superiorly to level of L2, anteriorly and to the left of the aorta
At duodenaljejunal flexure the duodenum bends anteriorly, and is continuous with the jejunum - hence the flexure marks the start of the intraperitoneal jejunum
How does the duodenum appear in a radiograph using fluid containing barium salts? Why?
First part = smooth area called duodenal cap
Remainder - barium broken up by the PLICAE CIRCULARES, giving it an irregular appearance
Radiological appearance of carcinoma and peptic ulcer?
??
Describe the interior of the duodenum
How can it be visualised?
Mucous membrane is thick
First part smooth but remainder thrown into numerous circular folds - the plicae circularis - functional significance = villi and microvilli to increase surface area for absorption
Visualised by endoscope or indirectly using radiography (ingest radio-opaque medium - barium salts = barium meal)
What is the blood supply to the duodenum?
Proximal duodenum (originates from foregut) receives blood from the celiac artery, distal duodenum (originates the midgut)= superior mesenteric artery
Gastroduodenal artery —> SUPERIOR PANCREATICODUODENAL artery - supplies proximal
Part of duodenum distal to major duodenal papilla supplied by INFERIOR PANCREATICODUODENAL artery (branch of superior mesenteric)
(Pancreaticoduodenal arteries are very small - don’t need to identify them)
What is the venous drainage of the duodenum?
Drainage via SUPERIOR MESENTERIC, SPLENIC veins or directly into HEPATIC PORTAL vein
(note: no gastroduodenal vein)
What is the lymphatic drainage of the duodenum?
Lymphatic vessels follow the arteries
Anterior vessels drain into PANCREATICODUODENAL nodes of the SUPERIOR and INFERIOR PANCREATICODUODENAL ARTERIES
- Then drains to PYLORIC nodes of the GASTRODUODENAL artery, then CELIAC nodes
Posterior vessels drain directly into SUPERIOR MESENTERIC nodes
Surface anatomy of duodenum?
- Retroperitoneal structure - position relatively fixed
- Lies in epigastric and umbilical regions
- Surface markings can be projected onto anterior abdominal wall (vertebral levels and costal cartilages)
1st: commences at pyloroduodenal junction to right of midline at about L1 (8th costal cartilage?)
2nd: (down past 10th costal cartilage?)
3rd: passes transversely across PAW at about L3
4th: passes superiorly to level of L2, anteriorly and to the left of the aorta (about 9th costal cartilage?)
