GI Anatomy Flashcards
what are the booundaries of the abdominal wall?
- Xiphisternum
- Costal margin
- Iliac crests
- Anterior superior iliac spines (ASIS)
- Pubic tubercles
- Pubic symphysis (a fibrocartilaginous joint).
what are the four quadrants of the abdominal wall?
what are the nine regions of the abdominal wall and what are the lines that divide it?
subcostal L3
intertubecular L5
where is the transpyloric plane?
a horizontal line that passes through the tips of the right and left ninth costal cartilages. It lies halfway between the superior border of the manubrium and the pubic symphysis. It transects the pylorus of the stomach, the gallbladder, the pancreas and the hila of the kidneys.
at what level is the transumbilical plane?
L3 (but only on slender individual)
where is the intercristal plane?
a horizontal line drawn between the highest points of the right and left iliac crests. It cannot be palpated from the anterior aspect of the abdominal wall. It is used to guide procedures on the back (e.g. lumbar puncture).
Where is McBurney’s point?
What does it indicate the position of?
It lies two thirds of the way along a line drawn from the umbilicus to the right anterior superior iliac spine.
indicated base of appenidx
what are the four pairs of muscle in the anterolateral abdominal wall?
- External oblique (medially inferiorly)
- Internal oblique (medially superiorly
- Transversus abdominis (horizontally orientated fibres)
- Rectus abdominis (rectus = straight).
what divides the rectus abdominis?
linea alba, covered by rectus sheath
Blood supply to the anterior abdominal wall?
Musculophrenic artery (from Internal Thoracic)
Superior Epigastric artery (from internal Internal thoracic)
Inferior Epigastric artery (from external iliac)
innervation of the anterior abdominal wall?
The muscles and skin of the anterolateral abdominal wall are innervated by:
● Thoraco-abdominal nerves T7 – T11. These are essentially the continuation of the intercostal nerves T7 – T11. These somatic nerves contain sensory and motor fibres.
● The subcostal nerve – this originates from the T12 spinal nerve (so called because it runs along the inferior border of the 12th rib).
● Iliohypogastric and ilioinguinal nerves – both are branches of the L1 spinal nerve.
what are the borders of the inguinal canal?
How long is it in adults?
The contents of the inguinal canal are different between males and females.
what is a hernia?
A hernia is an abnormal protrusion of tissues or organs from one region into another through an opening or defect. Herniae of the anterior abdominal wall may occur if the muscles are weak or have been incised during surgery. A segment of the small intestine may protrude through a defect in the wall, forming a visible and palpable lump under the skin.
what is an indirect hernia?
when would it be a surgical emergency?
In an indirect inguinal hernia, intra-abdominal contents are forced through the deep inguinal ring and into the canal. The abdominal contents may even be forced along the canal and through the superficial ring. From here, the hernia may extend into the scrotum in males or into the labia majora in females. Indirect hernias are more common than direct hernias. They are more likely to get stuck in the canal and become ‘irreducible’. Potentially, herniated tissue can ‘strangulate’ and become ischaemic. This is a surgical emergency.
what is the peritoneum?
Peritoneum is a serous membrane that lines the abdominal wall and covers the viscera within it.
how is pain in the parietal peritoneum felt?
Somatic Nerves:
Sharp, severe, localised
How is pain from the visceral peritoneum felt?
Viscertal Sensory Nerves:
severe, dull and diffuse
may be percieved as nausea or distension
which structures are retroperitoneal?
S for suprarenal glands.
A for aorta and inferior vena cava.
D for duodenum.
P for pancreas.
U for ureters.
C for colon (SOME)
K for kidneys.
E for esophagus.
R for rectum
The appendix, transverse colon, and sigmoid colon are intraperitoneal organs. The cecum also is located intraperitoneally, but it lacks a mesentery.
What do the mesenteries of the abdomen do?
Mesenteries are folds of peritoneum that contain fat and suspend the small intestine and parts of the large intestine from the posterior abdominal wall. Arteries that supply the intestine (from the abdominal aorta) and veins that drain the gut (tributaries of the portal venous system) are embedded in the mesenteries.
what are the greater and lesser omenta and what do they do?
The greater and lesser omenta are folds of peritoneum that are usually fatty and connect the stomach to other organs.
* The greater omentum hangs from the greater curvature of the stomach and lies superficial to the small intestine.
* The lesser omentum connects the stomach and duodenum (the first part of the small intestine) to the liver. The hepatic artery, the hepatic portal vein, and the bile duct (the ‘portal triad’) are embedded within its free edge.
what are the ligaments in the abdomen?
Ligaments are folds of peritoneum that connect organs to each other or to the abdominal wall. Some peritoneal ligaments that we will come across later are the:
* falciform ligament, which connects the anterior surface of the liver to the anterior abdominal wall
* the coronary and triangular ligaments, which connect the superior surface of the liver to the diaphragm.
where are the lesser and greater sacs?
what structure allows them to communicate?
Lesser sac (omentun bursa): posterior to tomach, anterior to pancreas
Greater sac: remaining part of peritoneal cavity
Epiploic foramen (or omental foramen)
embryologically, what do the lesser omentum and falciform ligament arrise from?
From the Ventral mesentery (connecct stomach to anterior abdominal wall)
Anterior Ventral mesentery –> Falciform ligament
Posterior Ventral Mesentery –> Lesser Omentum
Two mesenteries embryologically :
Dorsal mesentery = major branches of abdominal aort and
Ventral mesentery = above
at what level does the oesophagus enter the diaphram?
T10 (I 8 10 EgGs At 12)
Oesophageal Hiatus acts as Sphincter to prevent reflux.
Abdominal segment of oesophagus is less than 2cm long
blood supply to the distal oesophagus?
why is the venus system important?
Left Gastric Artery
Venous = both the systemic system of veins (via oesophageal veins that drain into the azygos vein) and to the portal venous system (via the left gastric veins). The distal oesophagus is thus a site of portosystemic anastomoses, which are clinically important.
Venous drainage of small & large intestine
Inferior mesenteric + splenic
+ superior mesenteric = hepatic portal
Hepatic portal➡️ liver
Processed
➡️ hepatic veins➡️ inferior vena cava
Innervation of small and large intestine
As a rule, visceral sensory fibres that travel with sympathetic nerves convey painful sensations, whereas visceral sensory fibres that travel with parasympathetic nerves convey information that maintains the internal environment and elicits reflex responses.
The liver has how many lobes? Separated by what?
Two anatomical lobes (large right, small left)
-Separated by falciform ligament
Two accessory lobes (caudate and quadrate)
Internally the liver is organised into eight functionalsegments with its own branch of hepatic artery, portal vein and hepatic duct
’
The common bile duct and main pancreatic duct merge at the
hepatopancreatic ampulla
The hepatopancreatic ampulla opens into the second part of the duodenum at the major duodenal papilla, which is located on the internal wall of the duodenum, about halfway along its length. The hepatopancreatic ampulla is surrounded by smooth muscle - the hepatopancreatic sphincter (sometimes called the sphincter of Oddi). Contraction of the sphincter prevents reflux of duodenal contents into the common bile duct and main pancreatic duct.
