GI/Liver: Anatomy Flashcards
Name four functions of the abdominal wall.
- Protect abdominal viscera (organs).
- Increase intra-abdominal pressure (e.g. for defecation).
- Maintain posture.
- Movement of the trunk.
What lines the internal aspect of the abdominal wall?
The parietal peritoneum.
Name the five palpable bony landmarks that define the boundaries of the abdominal cavity.
- Xiphisternum.
- Costal margin.
- Iliac crests.
- ASIS (anterior superior iliac spine).
- Pubic tubercles.
What are the iliac crests and where are they palpable?
Most superior aspect of the pelvis, palpable on the back.
What is the ASIS (anterior superior iliac spine)?
Prominent part of the pelvis that protrudes anteriorly above the hips.
What does the horizontal line that divides the upper and lower quadrants of the abdomen run through?
The umbilicus.
At what vertebral level is the inter-tubercular line that helps divide the 9 regions of the abdomen?
L5.
What 4 lines divide the abdomen into the 9 regions?
Left and right mid-clavicular lines.
Subcostal line.
Inter-tubercular line.
What are the 9 regions of the abdomen?
Central:
Epigastrium.
Umbilical.
Suprapubic (AKA hypogastric region).
Right and left:
Hypochondrium.
Flank (AKA lumbar regions)
Iliac fossa
What are the four pairs of muscles comprising the anterolateral abdominal wall?
External oblique.
Internal oblique.
Transversus abdominis
Rectus abdominis.
What is the name of the fibrous envelope surrounding the rectus abdominis muscles?
The rectus sheath.
What three structures do the rectus abdominis muscles attach to?
- Sternum.
- Costal margin.
- Pubis.
What muscles are referred to by the term “six pack”? Why?
Rectus abdominis; on either side of the midline. Segmented by horizontal tendinous intersections, muscle bulges on either side of these when they hypertrophy with exercise.
What skeletal movement does contraction of the rectus abdominis achieve?
Flexing of the spine, bringing the thorax closer to the pelvis.
List the muscles of the abdominal wall which are lateral to the rectus abdominis in order of most superficial to most deep.
- External oblique
- Internal oblique
- Transversus abdominis.
What happens when the external obliques, internal obliques, and transversus abdominis are contracted together?
Intra-abdominal pressure is increased.
What movement are the obliques involved in?
Lateral flexion of lumbar spine and rotation of the torso.
What is an aponeurosis?
Tendon of a flat muscle.
What is the linea alba?
The area of dense fibrous tissue in the midline where the aponeuroses of the abdominal muscles (obliques and transversus abdominis) fuse together. Encase the rectus abdominis and form the rectus sheath.
The aponeuroses of which muscles of the abdominal wall splits into anterior/posterior to form the innermost layer of the rectus sheath?
The internal obliques.
What tissue lies deep to the transversus abdominis?
Transversalis fascia.
Which spinal nerves innervate the abdominal wall?
Thoraco-abdominal nerves (T7-T11)
Subcostal nerve (T12)
Iliohypogastric and ilioinguinal nerves (branches of L1)
What is the inguinal canal?
An oblique passageway through the anterior abdominal wall.
On average in adults how long is the inguinal canal?
5cm.
Between what two structures does the inguinal canal run?
Deep inguinal ring and the superficial inguinal ring.
What is the function of peritoneal fluid?
To allow the visceral and parietal perineums to slide freely along each other.
What does intraperitoneal viscera refer to?
Organs in the abdominal cavity which are almost completely covered by peritoneum e.g. the stomach.
What does retroperitoneal refer to?
Structures in the abdominal cavity which are only covered by peritoneum on their anterior surface e.g. the pancreas.
What and where is the greater omentum?
Fatty fold of peritoneum hanging from the greater curvature of the stomach and rests on top of the small intestine. The transverse colon is embedded in the greater omentum.
What and where is the lesser omentum?
Fatty fold of peritoneum hanging from the lesser curvature of the stomach and connects the stomach and duodenum to the liver.
What three structures are embedded in the lesser omentum? What term refers to these three structures together?
Hepatic artery, hepatic portal vein, and bile duct.
“The portal triad”
What are mesenteries?
Folds of peritoneum that suspend the small intestine and parts of the large intestine from the posterior abdominal wall.
What vessels are embedded in the mesenteries?
Arteries that supply the intestines (branches of the abdominal aorta).
Veins that drain the gut (tributaries of the portal venous system).
What abdominal organs develop from the foregut?
Liver, gallbladder, and pancreas, distal oesophagus, stomach, and first half of the duodenum.
What artery branching from the abdominal aorta supplies all organs which derive from the foregut?
The coeliac trunk.
What section of the GI tract does the midgut give rise to?
Second half of duodenum, small intestine, and large intestine - ending 2/3 of the way along the transverse colon.
What artery branching from the abdominal aorta supplies all organs which derive from the midgut?
Superior mesenteric artery.
What section of the GI tract does the hindgut give rise to?
Distal third of the transverse colon, descending colon, sigmoid colon, rectum, upper part of the anal canal.
What artery branching from the abdominal aorta supplies all organs which derive from the hindgut?
Inferior mesenteric artery.
Where does the nutrient-dense venous blood drained from the gut go?
To the liver via the portal vein.
Where is bile made?
In the liver.
Where is bile stored?
In the gallbladder.
Where and how does bile enter the gut?
Enters the duodenum, via the biliary tree.
What is the main function of bile?
To break down lipids so they can be absorbed by the small intestine.
What are four different terms for folds of peritoneum?
Ligaments, folds, omenta, and mesenteries.
What is the difference between intraperitoneal and retroperitoneal viscera?
Intraperitoneal = viscera which are completely surrounded by peritoneum, connected to abdominal wall by mesenteries so are more mobile.
Retroperitoneal = viscera only covered on anterior surface, no mesenteries so are less mobile.
Which 10 viscera are retroperitoneal?
Suprarenal (adrenal) glands
Aorta & IVC
Duodenum (2nd & 3rd segments)
Pancreas
Ureters
Colon (ascending & descending)
Kidneys
oEsophagus
Rectum
What type of nerves innervate the parietal peritoneum? Describe parietal peritoneum pain.
Same somatic nerves that supply overlying muscles and skin.
Pain is sharp, severe, well localised to abdominal wall.
What type of nerves innervate the visceral peritoneum? Describe visceral peritoneum pain.
Visceral sensory nerves.
Pain is dull, severe, poorly localised/diffuse.
Where is visceral pain from the different parts of the gut (foregut/midgut/hindgut) felt in the 9 regions?
Foregut = epigastrium.
Midgut = umbilicus.
Hindgut = suprapubic.
In which quadrant does the stomach mainly lie?
LUQ
Where does the foregut end and the midgut start?
Half-way along the duodenum.