The peritoneum - ANATOMY Flashcards
What is the peritoneum?
Inner lining of the abdominal caviity, containing a single continuous cell layer - squamous
Mesothelium
What is the difference between the peritoneal and abdominal cavity?
Peritoneal is contained in the peritoneum and
What is contained in the peritoneal cavity? What is it analogous to?
Peritoneal fluid
- Potential space
- Cavity
Organs are contained . in peritoneal reflections
- Mesenteries
Analogous to pleural cavity, where the lungs are suspended.
What does the GI tract consist of? What are the three regions?
Mouth and pharynx
Esophagus
Stomach
Duodenum
Jejunum, Ilium
Caecum, large intestine
Sigmoid colon, rectum and anus
Thoracic, ? and pelvic respectively
Middle region can be palpated
Embryologically, when does the gut tube develop?
4th week of life
How does the gut develop?
Mesoderm and endoderm invaginate, leading to the formation of the gut tube
It is suspended from the posterior abdominal wall by a peritoneal fold
- dorsal mesentery
What are mesenteries?
Folds in the peritoneum that attach viscera to the abdominal wall
Conduit for the vessels , nerves and lymphatics.
Define splanchnic
Something that pertains to an organ and does not ‘stick’ to a wall - check
What are the types of peritoneum?
Visceral
- Peritoneum that covers suspended organs
Parietal
- Lining the abdominal wall
What are the types of structure with respect to relationship with peritoneum?
INTRAparietal
- suspended from abdominal wall by mesenteries - in peritoneal cavity
- Small intestine
RETROparietal
- lies between parietal peritoneum and abdominal wall
- posterior abdominal wall
Give some examples of retroperitoneal organs
Kidneys, vessels, oesophagus, rectum, nerves
Duodenum
Pancreas
Colon
- intraparietal but then became retro as the mesenteries fused w body wall
How is the GI tract divided?
Foregut
- Distal 1/3 of oesophagus to the 2nd part of duodenum - bile duct
Midgut
- 2nd part of the duodenum to 2/3 along transverse colon
Hindgut
- Distal third of transverse colon to rectum
They all have different blood supplies and different nervous systems
How is the gut tube supported?
Dorsal mesentery
BUT, foregut has a ventral mesentery - contains pancreas, liver etc
What are the two sacs?
How is the lesser formed?
Lesser
- Omental bursa
- Contains liver and stomach only
- Formed when liver moves to the right, and mesentery and spleen move left forming a cavity to the posterior side
- Situated in space posterior to between stomach and liver
Greater
What is the greater omentum? How does it communicate with the lesser sac?
Apron that extends anterior to intestine, communicates with lesser sac via epiploic foramen
Which structures run through the lesser omentum?
HPV, hepatic artery and bile duct
Between liver and posterior abdominal wall
The free section is present due to the ending of the ventral mesentery
What are the peritoneal compartments?
Supracolic compartment
Transverse colon mesentery - marks junction for supra or infra colic compartments
Infracolic compartment
Left and right paracolic gutter - for asc and desc large intestine
Small intestine mesentery
How does fluid move in the peritoneum? What is the importance?
Upwards, towards underside of diaphragm
If cancer of the colon, and some cells are discarded, can move up and cause metastasis
How about inflammatory exudate?
Towards pelvis
What is the ‘general plan’ of the GI tract?
In to out
All muscles in GI are SMOOTH
Mucosa - has muscularis mucosae - for mucus movement Submucosa Muscularis - inner circular - outer longitudinal Serosa Mesentery
How does the oesophagus enter the abdomen?
Pierces diaphragm at T10
- muscular part
- this contributes to LOWER OESOPHAGEAL SPHINCTER
- prevents food from going back up
Summarise the structure of the stomach
Top to bottom
Fundus
Body
Pyloric antrum
Pyloric canal
(Clinical note – on chest x-rays be aware that you can often see a gas bubble in the fundus of the stomach lying directly beneath diaphragm. Do not confuse this air bubble with air in the peritoneum, say from an intestinal perforation.)
Outline the structure of the small intestine
Duodenum
Jejunum
Ileum
Outline the structure of the duodenum
Duodenal cap - superior
Major duodenal papilla - descending - pancreatic . duct
Inferior
Ascending
MOSTLY RETROPERITONEAL
Outline the structure of the jejunum and ileum
Proximal and distal parts respectively
J is larger
J has LESS prominent arterial arcades
J has longer vasa recta
What does the large intestine consist of? What distinguishes it from the small intestine?
Caecum Ascending colon Transverse colon Descending colon Sigmoid colon
Fatty tags
Ribbons of longitudinal muscles
WHich arteries supply the gut?
Arise from the aorta
Foregut - liver, pancrease and spleen
- COELIAC TRUNK
Midgut
- SUPERIOR MESENTERIC ARTERY
Hindgut
- INFERIOR MESENTERIC ARTERY
What are the branches of the coeliac trunk?
Left gastric
Common hepatic
Gastroduodenal
Splenic
What are the branches of the superior mesenteric artery?
Middle, right, ileo
-colic arteries
Jejunal and Ileal
arteries
What are the branches of the inferior mesenteric artery?
Left colic
Superior rectal
Sigmoid
Anastomosis occurs here where we have switching from superior to inferior arteries
Describe venous drainage of the abdomen and how they lead to portal vein
Splenic vein
Portal vein
Inferior mesenteric
Superior mesenteric
Inferior goes into splenic, goes into superior mesenteric, becomes portal
What are porto-systemic anastomoses?
When blockage occurs and leads to venous dilation.
How is the gut innervated?
Viscera
- AUTONOMIC
- Parasympathetic sensory regulates reflec gut function
- Vagus nerve
- Pelvic splanchnic nerve
- Parasympathetic sensory regulates reflec gut function
- Sympathetic PAIN
- Thoracic and lumbar splanchnic
