GI anatomy Flashcards
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum
What does peritoneal fluid consist of?
Water, electrolytes, leukocytes, and antibodies
Why is there peritoneal fluid present between parietal and visceral peritoneum?
Acts as a lubricant, enabling free movement of the abdominal viscera and the antibodies in the fluid fight infection
What are the two compartments of the greater sac?
Supracolic and infracolic
Where is the supracolic compartment of the greater sac and what does it contain?
Lying above the transverse mesocolon, containing the stomach, liver and spleen
Where is the infracolic compartment and what does it contain?
Lies below the transverse mesocolon, contains the small intestine, ascending and descending colon
How are the supracolic and infracolic compartments of the abdomen connected?
Via the paracolic gutters which lie between the posterolateral abdominal wall and the lateral aspect of the ascending or descending colon
What are the subphrenic recesses?
Potential spaces in the supracolic compartment of the greater sac. They are located between the diaphragm and the liver. There are left and right subphrenic spaces, separated by the falciform ligament of the liver.
Why are subphrenic abscesses more common on the right side?
Increased frequency of appendicitis and ruptured duodenal ulcers
What is the omental bursa?
The lesser sac
How is the omental bursa connected with the greater sac?
An opening in the omental bursa- the epiploic foramen. It is situated posterior to the free edge of the lesser omentum
Where is Calot’s triangle located?
At the porta hepatis of the liver- where the hepatic ducts and neurovascular structures enter/ exit the liver
What are the borders of Calot’s triangle?
Medial – common hepatic duct.
Inferior – cystic duct.
Superior – inferior surface of the liver.
What are the contents of Calot’s triangle?
The right hepatic artery
The cystic artery
The lymph node of Lund
Lymphatics
What are the roles of the abdominal peritoneum?
To support the viscera, and provide pathways for blood vessels and lymph to travel to and from the viscera
What are the two layers of abdominal peritoneum?
Parietal (lining the internal surface of the abdominopelvic wall) and visceral (covering the majority of the abdominal viscera)
What are the layers of abdominal peritoneum embyologically derived from?
Parietal- Somatic mesoderm
Visceral- Splanchnic mesoderm
Why is pain from parietal peritoneum well localised?
It recieves the same somatic nerve supply as the region of the abdominal wall it lines.
What are each of the layers of peritoneum sensitive to?
Parietal- Pressure, pain, laceration and temperature
Visceral- Stretch and chemical irritation
Why does the visceral peritoneum have a poorly localised pain response?
The visceral peritoneum has the same autonomic nerve supply as the viscera it covers
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum. It normally only contains a small amount of lubricating fluid
How can damage to the abdominal peritoneum occur?
Infection, Surgery, or injury
What does intraperitoneal mean?
The organ is enveloped by a visceral peritoneum, which covers the organ both anteriorly and posteriorly.
What are examples of intraperitoneal organs?
The stomach, liver, and spleen
What does retroperitoneal mean?
The organ is not associated with visceral peritoneum. They are only covered in parietal peritoneum, and that peritoneum only covers their anterior surface.
What are the primarily retroperitoneal organs?
Organs developed and remaining outside of the parietal peritoneum. The oesophagus, rectum and kidneys.
What are the secondarily retroperitoneal organs?
organs were initially intraperitoneal, suspended by mesentery. Through the course of embryogenesis, they became retroperitoneal as their mesentery fused with the posterior abdominal wall. Thus, in adults, only their anterior surface is covered with peritoneum. Examples of secondarily retroperitoneal organs include the ascending and descending colon.
Which of the abdominal viscera are retroperitoneal?
S = Suprarenal (adrenal) Glands A = Aorta/IVC D =Duodenum (except the proximal 2cm, the duodenal cap) P = Pancreas (except the tail) U = Ureters C = Colon (ascending and descending parts) K = Kidneys E = (O)esophagus R = Rectum By TeachMeSeries Ltd (2020)
What is a mesentery?
A double layer of visceral peritoneum. It connects an intraperitoneal organ to (usually) the posterior abdominal wall. It provides a pathway for nerves, blood vessels and lymphatics to travel from the body wall to the viscera.
What is omentum?
Sheets of visceral peritoneum that extends from the stomach and proximal part of the duodenum to other abdominal organs
How many layers of visceral peritoneum are in the greater omentum?
4
Where does the greater omentum attach?
It descends from the greater curvature of the stomach and proximal part of the duodenum, then folds back up and attaches to the anterior surface of the transverse colon
What is the role of the greater omentum?
It has a role in immunity
How many layers of visceral peritoneum are in the lesser omentum?
2
Where does the lesser omentum attach?
To the lesser curvature of the stomach and the proximal part of the duodenum to the liver
What are the two parts of the lesser omentum?
The hepatogastric ligament (the flat, broad sheet) and the hepatoduodenal ligament (the free edge, containing the portal triad)
What is a peritoneal ligament?
A double fold of peritoneum that connects viscera together or connects viscera to the abdominal wall
What is in the foregut?
oesophagus, stomach, pancreas, liver, gallbladder and the duodenum (proximal to the entrance of the common bile duct).
What is in the midgut?
duodenum (distal to the entrance of the common bile duct) to the junction of the proximal two thirds of the transverse colon with the distal third.
What is in the hindgut?
distal one third of the transverse colon to the upper part of the anal canal.
What are the borders of the inguinal triangle?
Medial- Lateral border of the rectus abdominis muscle
Lateral- Inferior epigastric vessels
Inferior- Inguinal Ligament
What is a hernia?
The protrusion of an organ or fascia through the wall of a cavity that normally contains it.
What happens in a direct inguinal hernia?
Bowel herniates through a weakness in the inguinal triangle, and enters the inguinal canal. Bowel can then exit the canal via the superficial inguinal ring and form a lump in the scrotum or labia majora.
What happens in an indirect inguinal hernia?
Where bowel enters the inguinal canal via the deep inguinal ring
How many vertibrae are in the lumbar spine?
5
Describe the vertibral bodies of the lumabr spine
They are large and kidney-shaped. They are deeper anteriorly than posteriorly, producing the lumbosacral angle. The vertebral foramen is trianglular in shape.
ransverse processes are long and slender.
Articular processes have nearly vertical facets.
Spinous processes are short and broad.
Accessory processes can be found on the posterior aspect of the base of each transverse process. They act as sites of attachment for deep back muscles.
Mammillary processes can be found on the posterior surface of each superior articular process. They act as sites of attachment for deep back muscles.
Where are the two types of joint in the lumbar spine?
Between vertebral bodies
Between vertebral arches
What are iliolumbar ligaments?
Fan-like ligaments radiating from the transverse processes of the L5 vertebra to the ilia of the pelvis
What is the cauda equina and where does it begin?
A bundle of lumar, sacral and coccygeal nerve roots. It begins at the level of L1
How many layers are in the abdominal fiscia?
Above the umbilicus- a single sheet of connective tissue
Below the umbilicus- a superficial fatty layer, and the membranous layer
What is the linea alba?
A fibrous structure that extends from the xiphoid process of the sternum to the pubic symphysis
What are the attachments of the external oblique?
Originates from ribs 5-12, and inserts into the iliac crest and pubic tubercle
What are the functions of the external oblique?
Contralateral rotation of the torso
What is the innervation of the external oblique?
Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Which way do the fibres of external oblique run?
Inferomedially (hands into pockets)
What are the attachments of the internal oblique?
Originates from the inguinal ligament, iliac crest and lumbodorsal fascia, and inserts into ribs 10-12.
What are the functions of the internal oblique?
Bilateral contraction compresses the abdomen, while unilateral contraction ipsilaterally rotates the torso.
What is the innervation of the internal oblique?
Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus.
In which direction do the fibres of the internal oblique run?
Superomedially
What are the attachments of the transversus abdominis?
Originates from the inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia. Inserts into the conjoint tendon, xiphoid process, linea alba and the pubic crest.
What are the functions of the transversus abdominis?
Compressio of abdominal contents
What is the innervation of the transversus abdominis?
Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus.
What are the attachments of the rectus abdominis?
Originates from the crest of the pubis, before inserting into the xiphoid process of the sternum and the costal cartilage of ribs 5-7.
What are the functions of the rectus abdominis?
As well as assisting the flat muscles in compressing the abdominal viscera, the rectus abdominis also stabilises the pelvis during walking, and depresses the ribs.
What is the innervation of rectus abdominis?
Thoracoabdominal nerves (T7-T11).
What are the attachments of the pyramidalis?
Originates from the pubic crest and pubic symphysis before inserting into the linea alba.
What are the functions of the pyramidalis?
It acts to tense the linea alba.
What is the innervation of pyramidalis?
Subcostal nerve (T12).
What are the vertical lines dividing the 9 abdominal regions?
The mid-clavicular lines
What are the horizontal lines dividing the 9 abdominal regions?
The transpyloric plane and the intertubercular plane
What are the 9 abdominal regions?
Right hypochondrium Epigastrium Left hypochondrium Right flank Umbilical Left flank Right groin Pubic Left groin
In which of the 9 abdominal areas is the liver in?
Mainly in the right hypochondrium and epigastric areas, and extending into the left hypochondrium
Describe the diaphragmatic surface of the liver
The anterosuperior surface of the liver. It is smooth and convex, fitting snugly beneath the curvature of the diaphragm. The posterior aspect of the diaphragmatic surface is not covered by visceral peritoneum, and is in direct contact with the diaphragm itself.
Describe the visceral surface of the liver.
The posteroinferior surface of the liver. With the exception of the fossa of the gallbladder and porta hepatis, it is covered in peritoneum. It is moulded by the shape of the surrounding organs, making it irregular and flat. It lies in contact with the right kidney, right adrenal gland, right colic flexure, transverse colon, first part of duodenum, gallbladder, oesophagus and the stomach.
Describe the falciform ligament
this sickle-shaped ligament attaches the anterior surface of the liver to the anterior abdominal wall and forms a natural anatomical division between the left and right lobs of the liver. The free edge of this ligament contains the ligamentum teres, a remnant of the umbilical vein.
Describe the coronary ligament
attaches the superior surface of the liver to the inferior surface of the diaphragm and demarcates the bare area of the liver The anterior and posterior folds unite to form the triangular ligaments on the right and left lobes of the liver.