3.1. Abdomen

components of the abdomen, functions, major vessels, muscles

How long is the small intestine?

Approximately 6-7 metres

What are the three parts of the small intestine in order?

Duodenum, jejunum, ileum

Where does the small intestine extend from and to?

From the pyloric orifice (stomach) to the ileocaecal fold (caecum)

What is the shape of the duodenum and where is it located?

C-shaped and mainly retroperitoneal

What opens into the duodenum at the major duodenal papilla?

The bile duct and pancreatic duct

Where is the jejunum mostly located?

Upper left quadrant (proximal 2/5 of small intestine)

Where is the ileum mostly located?

Lower right quadrant (distal 3/5 of small intestine)

How long is the large intestine?

Approximately 1.5 metres in adults

What are the functions of the large intestine?

Absorbs fluids and salts from gut contents and forms faeces

What are the components of the large intestine in order?

Caecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anus

What are the characteristic landmarks of the colon?

Taeniae coli, haustra, and epiploic appendages

What is the appendix?

A hollow, blind-ended tube located at the caecum at the junction with the ileum, containing lymphoid tissue

What are the possible positions of the appendix?

Retrocaecal, retrocolic, subcaecal, pelvic/descending, pre-ileal, post-ileal

What are the two functions of the pancreas?

Endocrine (hormones) and exocrine (digestive enzymes)

What are the regions of the pancreas?

Head, uncinate process, neck, body, and tail

Where is the pancreas located?

Posterior to the stomach, primarily retroperitoneal

Where do the pancreatic duct and bile duct meet?

At the hepatopancreatic ampulla, opening at the major duodenal papilla

What is the spleen?

The largest lymphatic organ, located in the left hypochondrium

What are the functions of the spleen?

Proliferation of white blood cells, filtration and removal of red blood cells, and acting as a blood reservoir

Which ribs is the spleen associated with?

Ribs IX and X

What is the position of the spleen relative to surrounding structures?

Posterior to the stomach, lateral to the left kidney, inferior to the diaphragm, and superior to the left colic flexure

Why is the spleen prone to danger in trauma?

Because it is a blood reservoir, internal haemorrhage from splenic damage can be severe

What is the largest visceral organ?

The liver

Where is the liver located?

Primarily in the right hypochondrium and epigastric region

What are the primary functions of the liver?

Bile production/excretion, metabolism of fats/proteins/carbohydrates, glycogen and vitamin/mineral storage, synthesis of plasma proteins and clotting factors, blood detoxification, and enzyme activation

What are the lobes of the liver?

Right, left, caudate, and quadrate lobes

What separates the right and left lobes of the liver?

The falciform ligament

What is the function of the gallbladder?

To receive, concentrate, and store bile

What are the components of the gallbladder?

Fundus, body, and neck

What is the clinical significance of the gallbladder?

It is a common site for gallstones

What are the ureters and where do they run?

Tubes running from the renal pelvis to the bladder, crossing over the iliac vessels in the pelvis

What are ureteric strictures and why are they clinically important?

Three narrow points along the course of the ureters where kidney stones are most likely to get stuck

What are the three unpaired arteries supplying the abdomen from the aorta?

Coeliac trunk, superior mesenteric artery, and inferior mesenteric artery

Which artery supplies the foregut?

Coeliac trunk

What structures does the coeliac trunk supply?

Stomach, liver, gallbladder, spleen, pancreas, and duodenum

What is the hepatic portal vein formed from?

Splenic vein + inferior mesenteric vein + superior mesenteric vein

What is unique about venous drainage of the abdominal digestive tract?

Blood from the spleen, pancreas, gallbladder, and abdominal digestive tract travels to the liver via the portal system, not directly to the heart

Which regions drain into the caval (systemic) system rather than the portal system?

Pelvic regions and the middle/inferior rectum, draining into the iliac veins and then the inferior vena cava

What are anastomoses in the context of portal and caval systems?

Links between portal and caval venous drainage that are clinically important in portal hypertension

What are oesophageal and rectal varices?

Dilated veins at anastomoses between portal and caval systems, which can bleed severely in portal hypertension

What are the posterior abdominal wall muscles?

Psoas major, psoas minor, quadratus lumborum, and iliacus (and diaphragm)

What is the peritoneum?

A membrane covering the viscera and lining the abdominal walls

What does intraperitoneal mean?

An organ surrounded or suspended by peritoneal folds

What does retroperitoneal mean?

An organ located outside the peritoneum

What mnemonic is used to remember retroperitoneal organs?

SADPUCKER

What is the shape of the stomach?

J-shaped

What are the main features of the stomach?

Greater and lesser curvature, cardia and cardiac notch, fundus, body, pyloric antrum and sphincter

What are the skeletal components of the abdominal wall?

Vertebrae LI-LV, superior parts of pelvic bones, rib XII, rib XI, xiphoid process, and costal margin

What muscles form the posterior abdominal wall?

Quadratus lumborum, psoas major, and iliacus

What muscles form the lateral abdominal wall?

Transversus abdominis, internal oblique, and external oblique

What muscles form the anterior abdominal wall?

Rectus abdominis (and pyramidalis)

What are the three flat anterolateral abdominal muscles?

External oblique, internal oblique, and transversus abdominis

What do the three flat anterolateral muscles form anteriorly?

A tendinous sheath for the vertical midline muscles

What are the vertical midline abdominal muscles?

Rectus abdominis and pyramidalis

How is the abdomen divided into quadrants?

A horizontal line through the umbilicus and LII/LIV intervertebral disc, and a vertical line in the median plane

How is the abdomen divided into 9 regions?

Two vertical lines along mid-clavicular planes and two horizontal lines — the subcostal plane (LIII) and intertubercular plane (LV)

What forms the superior boundary of the abdomen?

The inferior thoracic aperture (diaphragm)

What forms the inferior boundary of the abdomen?

The pelvic inlet (deep) and the superior part of the lower limb (superficial)

Which of the following is mainly retroperitoneal and begins at the pyloric orifice?  

Duodenum

The descending colon is found in which region?

Left flank

Which of the following is intraperitoneal and mainly located in the upper left quadrant?  

Jejunum

Which of the following is NOT a characteristic landmark of the large intestine/colon?

 Mesentery (peritoneal covering)

Regarding the gall bladder, which of the following is correct?

It lies on the visceral surface of the liver

On the visceral surface on the liver, the colic impression is formed by the:

Right colic flexure

The stomach is found in which region?

Epigastric

On the visceral surface on the liver, the renal impression is formed by the:

Right kidney

Which of the following anterior abdominal muscles lies the deepest?

Rectus abdominis

Which of the following does NOT form part of the abdominal wall?

Vertebrae TIX-TXII

Of the anterolateral abdominal wall muscles, which is the most superficial? 

External oblique