Anatomy of the Abdomen 1 Flashcards
Label the surface abdominal landmarks
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Where is the pubic symphysis found?
Found at the midline
What level is the umbilicus found and run along?
Belly button (umbilicus (L4)) – the umbilicus runs through a structure in the midline of the body called the linea alba (means white line) (we will come to this)
What are Tendinous intersections?
• Tendinous intersections – these make out the midline of the six pack of the rectus abdominus muscle
What line is lateral to the linea alba?
linea semilunaris (semilunar line)
Label the 4 abdominal quadrants and what are they separated by?
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Label the 9 abdominal quadrants
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What level is the transpyloric plane AND Transtubecular plane?
What level is the subcostal plane at?
What lies at these planes?
L1 AND L4/5
- Transpyloric: Midway between jugular notch and pubic symphysis
- Transtubecular: Through iliac tubercles
Describe and label the 3 components of the layers of the abdominal wall: superficial fascia, anterolateral muscles and rectus sheath
What are the two layers of the superficial fascia?
What direction does fibres of external oblique muscle run? What ligament is at the inferior border?
What forms the rectus sheath and what does it envelope?
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What muscles make up the anterolateral muscle?
What direction do these muscles run?
What is the function of the transversus abdominis?
What is the function of the rectus abdominis and pyramidalis?
What forms the deep layers of the abdomen?
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What does the fibrous compartment of the rectus sheath house?
Aponeuroses of EO, IO and TA
Rectus abdominas, pyramidlais, superior and inferior epigastric arteries, lymphatics, distal portion of thoracolumbar nerves
What is the linea alba made of?
Where does it run from?
What is at the midline of the linea alba?
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Describe the rectus sheath below and above the arcuate line
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What arteries supply the superior anterolateral wall of the abdomen?
Musculophrenic artery
Superior epigastric artery
What is the inferior anterolateral wall supplied by?
Superficial Circumflex iliac
Superficial epigastric
Inferior epigastric
Deep circumflex iliac
What does direct trauma to the anterior abdominal wall cause?
Rupture the inferior epigastric artery causing a rectus sheath haemotoma
What nerves supply the abdomen and where do they run?
• The abdomen is supplied by the nerves from T7-L1, these are the dermatome nerves the cutaneous sensory supply
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What thoracic nerve is supplies the umbilicus?
• The umbilicus is at the level of T10
What is the inguinal canal?
What does it permit in males and females?
Where are the two openings of the inguinal canal?
An oblique passage (tunnel) that extends downwards and medially through the lower anterior abdominal wall
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Label the inguinal canal
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In the fetus where are the gonads found?
Where do they burrow?
What pulls the gonads downwards?
- In the foetus the gonads develop high up on the posterior wall between the parietal peritoneum and the transversalis fascia.
- They then burrow their way to lie within the scrotum in the male, or reside within the pelvis of the female
- The structure that pulls the gonads inferiorly is called the Gubernaculum (a chord like mesenchymal structure that attaches to the tail end of the gonads and drags them down into the pelvis (for ovaries)
- Once the gonad reaches the anterior abdominal wall, there is an invagination of the parietal peritoneum (the invagination is called the process vaginalis)
- The Gubernaculum continues to pull the testes along the root of the process vaginalis, so the testes pick up the layers of the anterior abdominal wall
- Eventually the process vaginalis will start to close over, apart from the bottom part of the testes (called the tunica vaginalis)
- From out to in we can see: external oblique, internal oblique and transverse abdominus which continue around the testes
What is an inguinal hernia?
• The fact that the spermatic cord runs through the wall gives rise to a weakness, a part of the gut can slip through the abdomen and come lie outside the abdominal cavity, when this happens it is called the inguinal hernia
What is a direct inguinal hernia?
• Direct Hernia – this is where part of the gut (omentum) will slip through the layers of the anterior abdominal wall. This occurs medial to the inferior epigastric artery.
What is a indirect inguinal hernia?
• Indirect Hernia (congenital) – the process vaginalis does not close over, so there is an opening directly from the abdominal cavity into the scrotum. Part of the gut or omenta will slip through the inguinal canal and will lie inside the scrotum. These hernias are located lateral to the inferior epigastric artery.
Who are hernias more common in?
• Because the spermatic cord is much larger than the round ligament in female these hernias are more common in males than in females.
What is the viscera and perineum of the abdominal cavity?
Viscera – represents the organs and all of the neurovasculature, these include the organs of the GI tract and accessory organs of digestion including the liver, pancreas, spleen. It also includes the genitourinary system such as the kidneys, ureters ect.
Each of these viscera is wrapped in peritoneum (a serous membrane which lines the organs). When it lines the organs it is called visceral peritoneum and when it lines the body wall is called parietal peritoneum
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What is the perineal cavity?
What does the perineal cavity contain?
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What are the 2 divisions of the peritoneum and what are they sensitive to?
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What does it mean when an organ is intraperitoneal?
What can a double fold in the visceral peritoneum be called and form, what is the function of this?
- Organs are related to the peritoneum in a few different ways
- Organs are described as intraperitoneal, this means the organ is completely covered in visceral peritoneum.
- The visceral peritoneum encloses the whole organ, the layers of visceral peritoneum then reflect off the organ and come together as a double fold. This fold is sometimes called a mesentery, a ligament or Omentum.
- This fold means that the organ has greater mobility, so it can move.
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What does it mean when an organ is extraperitoneal?
- Here the organs are partially or entirely devoid of peritoneum. This means the organ lies outside the peritoneal cavity
- According to the position organs can be retroperitoneal (peritoneum passes over the organ pushing it against the wall body) or sub-peritoneal (peritoneum passes over the organ such as the bladder). These organs are immovable.
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What are the perineal positions?
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What are the 7 functions of the perineal folds?
Peritoneal Folds: Function
• Route of blood vessels, lymphatics, nerves
• May contain embryological remnants
o Falciform ligament of liver: umbilical vein
• Contains varying amounts of fat
o Greater omentum (high volume)
o Lesser omentum (devoid of fat)
• May contain intraperitoneal parts of organs
o Tail of pancreas lies in splenorenal ligament
• Immunity
• Greater omentum: policeman of abdomen
• Prevents effects of gravity
What are the 3 reflections of peritoneum?
Label the peritoneal cavity
A reflection of peritoneum that connects organs to another organ or to the abdominal wall:
1. omenta
2. mesenteries
3. ligaments
A reflection of peritoneum that is raised from the body wall by underlying blood vessels, ducts and ligaments formed by obliterated foetal vessels.
What is the lesser omentum and 2 ligaments of it?
Label these
Double fold of peritoneum that connects the inferior surface of the liver to the lesser curvature of the stomach and first part (superior region) of duodenum
- Hepatogastric ligament
- Hepatoduodenal ligament
What is the greater omentum?
Label these
Double fold of peritoneum folded back on its self (four layers), forming an apron like structure that hangs from the greater curvature of stomach:
• Policeman of abdomen
• Varying degrees of fat
What is the mesentery?
What does it contain?
Label this
Fan-shaped double fold of peritoneum that suspends the jejunum and ileum from the posterior abdominal wall.
Contains: Superior mesenteric artery (1) + vein (2) branching within the mesentery to supply the organ .
It is connected to the posterior abdominal wall by the root of the mesentery (where the two folds of peritoneum are reflected off the back wall to form a moveable double folded peritoneum)
Describe the Peritoneal Recesses
Why are they clinically relevant?
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What are the 3 sections of the GI tract and what is there blood supply?
The GI tract develops in 3 sections, the foregut, midgut and hindgut.
Each of these 3 sections has a distinct blood supply:
The foregut is supplied by branches of the coeliac trunk, a vessel that arises from the aorta at the level of T12.
The midgut is supplied by branches from the superior mesenteric artery that is a branch from the aorta at the level of L1
The hindgut is supplied by a branch from the inferior mesenteric artery that arises from the aorta at the level of L3.
How long is the oesophagus?
What is the function of the oesophagus?
Where does it extend from?
Where does it pierce the diaphragm?
- Muscular tube: 25 cm
- Functions to transport food from pharynx to stomach via peristaltic waves
- Extends from pharyngo-oesophageal junction (C6) to cardiac orifice of stomach (T11)
- Pierces diaphragm at oesophageal hiatus (T10)
What are the two anti reflux sphincters of the oesophagus?
What are they composed of?
• Two anti-reflux barrier sphincters
o Upper oesophageal sphincter (UES)
• Anatomical sphincter composed off Cricopharyngeus muscle
o Lower oesophageal sphincter (LES)
• Functional sphincter composed off:
Thickening of circular smooth muscle
Angle oesophagus enters stomach
Crus of diaphragm
Malfunction of sphincter: Gastrooesophageal reflux disorder (GORD) may lead to Barrett’s oesophagus
• Change in cell lining (goes from squamous to columnar)
What is GORD?
Gastro-oesophageal reflux (GORD) also known as heartburn, is commonly associated with either a hiatus hernia or increased acid production in the stomach and peptic ulceration. Chronic reflex with acid and bile in the lower oesophagus can cause inflammation of the lining of the oesophagus and over many years may cause a change in cellular type leading to a pre-malignant condition known as Barrett’s oesophagus
Label the constrictions of the oesophagus
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What are the parts of the stomach?
What are the 4 features of the stomach?
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What are the openings of the stomach?
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What does the rugae of the stomach do?
What does the rugae form?
The rugae allow the stomach to distend having eaten a large meal, increase surface area of the stomach
The rugae form a temporary groove along the lesser curvature called the gastric canal to direct the flow of food down into the pylorus
The bottom right image shows a gastric tumour, which can be seen on these barium images
What are the arteries of the stomach?
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