Anatomy of the Abdomen 1

Question 1

Label the surface abdominal landmarks

Answer 1

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Question 2

Where is the pubic symphysis found?

Answer 2

Found at the midline

Question 3

What level is the umbilicus found and run along?

Answer 3

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)

Question 4

What are Tendinous intersections?

Answer 4

• Tendinous intersections – these make out the midline of the six pack of the rectus abdominus muscle

Question 5

What line is lateral to the linea alba?

Answer 5

linea semilunaris (semilunar line)

Question 6

Label the 4 abdominal quadrants and what are they separated by?

Answer 6

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Question 7

Label the 9 abdominal quadrants

Answer 7

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Question 8

What level is the transpyloric plane AND Transtubecular plane?

What level is the subcostal plane at?

What lies at these planes?

Answer 8

L1 AND L4/5

• Transpyloric: Midway between jugular notch and pubic symphysis
• Transtubecular: Through iliac tubercles

Question 9

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?

Answer 9

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Question 10

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?

Answer 10

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Question 11

What does the fibrous compartment of the rectus sheath house?

Answer 11

Aponeuroses of EO, IO and TA

Rectus abdominas, pyramidlais, superior and inferior epigastric arteries, lymphatics, distal portion of thoracolumbar nerves

Question 12

What is the linea alba made of?

Where does it run from?

What is at the midline of the linea alba?

Answer 12

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Question 13

Describe the rectus sheath below and above the arcuate line

Answer 13

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Question 14

What arteries supply the superior anterolateral wall of the abdomen?

Answer 14

Musculophrenic artery

Superior epigastric artery

Question 15

What is the inferior anterolateral wall supplied by?

Answer 15

Superficial Circumflex iliac

Superficial epigastric

Inferior epigastric

Deep circumflex iliac

Question 16

What does direct trauma to the anterior abdominal wall cause?

Answer 16

Rupture the inferior epigastric artery causing a rectus sheath haemotoma

Question 17

What nerves supply the abdomen and where do they run?

Answer 17

• The abdomen is supplied by the nerves from T7-L1, these are the dermatome nerves the cutaneous sensory supply

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Question 18

What thoracic nerve is supplies the umbilicus?

Answer 18

• The umbilicus is at the level of T10

Question 19

What is the inguinal canal?

What does it permit in males and females?

Where are the two openings of the inguinal canal?

Answer 19

An oblique passage (tunnel) that extends downwards and medially through the lower anterior abdominal wall

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Question 20

Label the inguinal canal

Answer 20

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Question 21

In the fetus where are the gonads found?

Where do they burrow?

What pulls the gonads downwards?

Answer 21

• 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

Question 22

What is an inguinal hernia?

Answer 22

• 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

Question 23

What is a direct inguinal hernia?

Answer 23

• 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.

Question 24

What is a indirect inguinal hernia?

Answer 24

• 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.

Question 25

Who are hernias more common in?

Answer 25

• Because the spermatic cord is much larger than the round ligament in female these hernias are more common in males than in females.

Question 26

What is the viscera and perineum of the abdominal cavity?

Answer 26

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 On image

Question 27

What is the perineal cavity? What does the perineal cavity contain?

Answer 27

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Question 28

What are the 2 divisions of the peritoneum and what are they sensitive to?

Answer 28

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Question 29

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?

Answer 29

* 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. On image

Question 30

What does it mean when an organ is extraperitoneal?

Answer 30

* 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. On image

Question 31

What are the perineal positions?

Answer 31

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Question 32

What are the 7 functions of the perineal folds?

Answer 32

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

Question 33

What are the 3 reflections of peritoneum? Label the peritoneal cavity

Answer 33

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.

Question 34

What is the lesser omentum and 2 ligaments of it? Label these

Answer 34

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 1. Hepatogastric ligament 2. Hepatoduodenal ligament

Question 35

What is the greater omentum? Label these

Answer 35

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

Question 36

What is the mesentery? What does it contain? Label this

Answer 36

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)

Question 37

Describe the Peritoneal Recesses Why are they clinically relevant?

Answer 37

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Question 38

What are the 3 sections of the GI tract and what is there blood supply?

Answer 38

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.

Question 39

How long is the oesophagus? What is the function of the oesophagus? Where does it extend from? Where does it pierce the diaphragm?

Answer 39

* 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)

Question 40

What are the two anti reflux sphincters of the oesophagus? What are they composed of?

Answer 40

• 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)

Question 41

What is GORD?

Answer 41

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

Question 42

Label the constrictions of the oesophagus

Answer 42

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Question 43

What are the parts of the stomach? What are the 4 features of the stomach?

Answer 43

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Question 44

What are the openings of the stomach?

Answer 44

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Question 45

What does the rugae of the stomach do? What does the rugae form?

Answer 45

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

Question 46

What are the arteries of the stomach?

Answer 46

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