Contents of the Abdomen Flashcards
anatomical regions of the abdomen
quadrants of the abdomen
Origins of Viscera:
- foregut
- midgut
- hindgut
Foregut & its Derivatives:
- all structures proximal to the major papilla
- stomach
- duodenum
- liver and billiary tract
- spleen
- pancreas
Midgut & its Derivatives:
- all structures distal to the major papilla to
2/3rd along transverse colon - duodenum small intestine
- ascending colon
- caecum
- appendix
- transverse colon
Hindgut & its Derivatives:
- all structures beyond distal 1/3rd transverse
colon - sigmoid colon
- rectum
- anal canal
Functions of the GI Tract:
- Ingestion
- Secretion (digestive fluids)
- Mixing and Propulsion
- Digestion (breaking down)
- Absorption
- Defecation
Key Histological Layers:
- Serosa
- Muscularis propria/externa
- Submucosa
- Mucosa
Serosa/Adventitia
an outer covering (peritoneum)
Muscularis Propria/Externa
- longitudinal (outer) and circular (inner)
- responsible for peristalsis (forward
movements) of contents
Submucosa
- loose connective tissue
- blood vessels, nerves, lymphatics
Mucosa:
- 3 subdivisions: epithelium (glandular), lamina
propria (loos connective tissue), muscularis
mucosa (smooth muscle) - inner layer
- secretory to aid peristalsis
Key Histological Layers
What is the most dilated part of the GI Tract?
Stomach
Stomach:
- where is it situated
- shape
- muscle layers
- between the oesophagus and small intestine
- J-shaped
- three layers of muscle: longitudinal, circular,
oblique
Functions of the Stomach:
- mechanical (muscle)
- chemical (gastric juices) initial phase of
digestion
Anatomy of Stomach (5):
- Cardia: Cardiac Sphincter
- Pylorus: Pyloric Sphincter
- Lesser Curvature: superior right border
- Greater Curvature: inferior left border
- Antrum
Small Intestine:
- is
- from where
- how long
- convoluted tube
- pylorus of stomach to ileocaecal junction
- 5/6 meters in length
Small Intestine is subdivided into:
- duodenum
- jejunum
- ileum
Functions of the Small Intestine:
- digestion
- absorption
Duodenum:
- how long
- location
- Shape and divisions
- joining of
- ends
- 20-25 cm
- retroperitoneal locations (except first 2 cm)
- C shaped: 4 parts: superior, descending,
horizontal, ascending - Medial border 2nd part:
- pancreatic duct + common bile duct join to
form hepatopancreatic ampulla (ampulla of
vater) to drain at the major duodenal
papilla - ends at the duodenojujenal junction (flexure)
Jejunum and Ileum:
- how long
- situated
- anchored to posterior abdominal wall by
- approx 3m
- from duodenojujenal junction to ileocaecal
junction - anchored to posterior abdominal wall by
peritoneal mesentery
Jejunum and Ileum Function:
- site of absorption:
- large surface area
- increased by circular folds + villi + microvilli
- motility
Duodenum
Jejunum:
- what % of small intestine
- characterised by
- arcades
- 40% of small intestine
- multiple folds with pronounced villi
- Arcades: fewer vessels, long vasa recta
Ileum:
- what % of small intestine
- characterised by
- arcades:
- 60% of small intestine
- thin walls and less fat in mesentery
- arcades: many but short vasa recta
Large Intestine:
- location
- comprises of
- length
- ilocaecal junction to anal canal
- comprises of colon, rectum and anus
- 1.5m in length: large surface area
Large Intestine:
- subdivisions
- ascending, transverse, descending, sigmoid
and caecaum - hepatic flexure consists of ascending and
transverse - splenic flexure consists of transverse and
descending
Anatomy of Large Intestine
Large Intestine: Rectum:
- 15cm long
- Rectosigmoid junction
Large Intestine: Anal Canal:
anal sphincters
Function of Large Intestine:
- absorption of water, forms and expels faeces
(defecation)
Three main branches of the abdominal aorta to the three sections of GI Tract:
- coeliac trunk/artery
- superior mesenteric artery
- inferior mesenteric artery
Blood Supply to GI Tract:
Coeliac Trunk:
- arises from
- 3 main branches for foregut and what each supplies
- arises from the aorta at T12
- Branches:
- left gastric artery (supplies stomach)
- splenic artery (supplies spleen)
- common hepatic artery (supplies liver, gallbladder,
stomach, duodenum and pancreas)
Venous drainage of GI Tract structures that are supplied by the coeliac trunk:
- stomach: local branches drain into the Portal Vein
- spleen: splenic vein: joins superior mesenteric vein to
form the portal vein - liver: hepatic veins: drain into the IVC
Label the branches of the coeliac trunk
Superior Mesenteric Artery:
- arises from
- supplies
- branches (4)
- arises from the abdominal aorta at L1
- supplies distal part of duodenum to proximal 2/3
transverse colon - Branches:
- Jejunal and Ileal branches
- Middle Colic
- Right Colic
- Ileocolic
Branches of the Superior Mesenteric Artery
Venous Drainage of the Small Intestine:
All branches of the superior mesenteric artery drain into the Superior Mesenteric Vein
Inferior Mesenteric Artery:
- arises from
- supplies
- branches (3)
- arises from the abdominal aorta at L3
- supplies distal 1/3 transverse colon to upper half of
anal canal - Branches:
- left colic
- sigmoid
- superior rectal
Branches of the Inferior Mesenteric Artery:
Venous Drainage of the Colon and Rectum:
All branches of the inferior Mesenteric Artery drain into the Inferior Mesenteric Vein, which drains into the Splenic Vein
Lymph nodes of the GI Tract:
Sympathetic Innervation of foregut, midgut and hindgut:
- Thoracoabdominal splanchnic nerves:
- Greater Splanchnic Nerve (T5-T9): Foregut
- Lesser Splanchnic Nerve (T10/11): Midgut
- Least Splanchnic Nerve (T12): Hindgut
- Lumbar Splanchnic Nerve (L1-2): Hindgut: Pelvis
- Sacral Splanchnic Nerve (S2-S4): Hindgut: Pelvis
Innervation of the foregut, midgut and hindgut: Label and mark which nerves are sympathetic and parasympathetic.
Parasympathetic innervation of the foregut, midgut and hindgut:
- Vagus (CNX): Foregut and Midgut
- Pelvic Splanchnic Nerves (S2-S4): Hindgut
Blood/Nerves/Lymphs of the Gut
