ANA 202 Abdominal Viscera

Question 1

Describe the greater omentum

Answer 1

The greater omentum is a large, apron-like, peritoneal fold that attaches to the greater curvature of the stomach and the first part of the duodenum.
•It drapes inferiorly over the transverse colon and the coils of the jejunum and ileum.
• Turning posteriorly, it ascends to associate with, but remain separate from, the peritoneum on the superior surface of the transverse colon and the transverse mesocolon before arriving at the posterior abdominal wall.

Throughout the peritoneal cavity numerous peritoneal folds connect organs to each other or to the abdominal wall.
•These folds (omenta, mesenteries, and ligaments) develop from the original dorsal and ventral mesenteries, which suspend the developing gastrointestinal tract in the embryonic coelomic cavity.

Usually a thin membrane, the greater omentum always contains an accumulation of fat, which may become substantial in some individuals.

•the right and left gastro-omental vessels, between this double-layered peritoneal apron just inferior to the greater curvature of the stomach.

Question 2

Describe the Lesser omentum

Answer 2

•It extends from the lesser curvature of the stomach and the first part of the duodenum to the inferior surface of the liver.

Question 3

Lesser omentum division

Answer 3

•a medial hepatogastric ligament, which passes between the stomach and liver;

•a lateral hepatoduodenal ligament, which passes between the duodenum and liver. It serves as the anterior border of the omental foramen.

the right and left gastric vessels are between the layers of the lesser omentum near the lesser curvature of the stomach.

Question 4

Why is the greater omentum termed the policeman of the abdomen?

Answer 4

act as a protective shield for the abdominal organs. It can wrap around organs that are inflamed or infected, isolating them from the rest of the abdominal cavity and preventing the spread of infection.

The greater omentum also contains a large number of immune cells, including macrophages and lymphocytes, which can help to fight off infections and other harmful substances in the abdomen. Additionally, the greater omentum is highly vascularized, meaning that it has a rich blood supply that can transport immune cells and other substances throughout the abdomen.

Question 5

Describe the location do the abdominal esophagus

Answer 5

Emerging through the right crus of the diaphragm, usually at the level of vertebra T10, it passes from the oesophageal hiatus to the cardial orifice of the stomach just left of the midline.

Question 6

Describe the abdominal esophagus in relation to the vagar trunk

Answer 6

the anterior vagal trunk consists of several smaller trunks whose fibers mostly come from the left vagus nerve-rotation of the gut during development moves these trunks to the anterior surface of the oesophagus;

•similarly, the posterior vagal trunk consists of a single trunk whose fibers mostly come from the right vagus nerve and rotational changes during development move this trunk to the posterior surface of the oesophagus

Question 7

Describe the stomach

Answer 7

The stomach is the most dilated part of the gastrointestinal tract and has a J-like shape.
• Positioned between the abdominal oesophagus and the small intestine, the stomach is in the epigastric, umbilical, and left hypochondrium regions of the abdomen.
•The stomach acts as a food blender and reservoir; its chief function is enzymatic digestion.

Question 8

Function of gastric juice

Answer 8

The gastric juice gradually converts a mass of food into a liquid mixture–chyme–that passes fairly quickly into the duodenum.

Question 9

How many L can the adult stomach hold?

Answer 9

2 to 3 litres of food.

Question 10

How many L can the child stomach hold?

Answer 10

30 mL of milk.

Question 11

Describe the pyloric orifice

Answer 11

The outlet of the stomach (pyloric orifice) is marked on the surface of the organ by the pyloric constriction and surrounded by a thickened ring of gastric circular muscle (the pyloric sphincter).
•The pyloric orifice is just to the right of midline in a plane that passes through the lower border of vertebra LI (the transpyloric plane).

Question 12

Describe the features of the stomach and their functions

Answer 12

the greater curvature, which is a point of attachment for the gastrosplenic ligament and the greater omentum;

•the lesser curvature, which is a point of attachment for the lesser omentum;

•the cardial notch, which is the superior angle created when the esophagus enters the stomach;

•the angular incisure, which is a bend on the lesser curvature.

Question 13

Derribe the posterior and anterior relations of the stomach

Answer 13

Anteriorly, the stomach is related to the diaphragm, the left lobe of liver, and the anterior abdominal wall.

•Posteriorly, the stomach is related to the omental bursa and the pancreas; the posterior surface of the stomach forms most of the anterior wall of the omental bursa.

Question 14

Features of the stomach bed

Answer 14

From superior to inferior, the stomach bed is formed by the:
• Left dome of the diaphragm
• Spleen
• Left kidney and suprarenal gland
•Splenic artery
•Pancreas
•Transverse mesocolon and colon.

Question 15

What are the most affected structures in stomach pathology?

Answer 15

Structures of the stomach bed

Question 16

Describe the vasculature of the stomach

Answer 16

The abdominal aorta has anterior, lateral, and posterior branches as it passes through the abdominal cavity.
•The three anterior branches supply the gastrointestinal viscera:
•the celiac trunk,
•superior mesenteric and inferior mesenteric arteries.

Question 17

The primitive foregut, midgut and hind guy is supplied by which branches of the anterior abdominal aorta?

Answer 17

foregut- celiac trunk
midgut- superior mesenteric
Hindgut- inferior mesenteric

Question 18

Describe the gastric arteries which arise from the celiac trunk and its branches

Answer 18

*Left gastric artery:, arises directly from the celiac trunk and runs in the lesser omentum to the cardia and then turns abruptly to course along the superior part of the lesser curvature of the stomach and anastomose with the right gastric artery.

*Right gastric artery: usually arises from the hepatic artery and runs to the left along the lower part of the lesser curvature to anastomose with the left gastric artery.

*Right gastro-omental artery (gastroepiploic artery): arises as one of two terminal branches of the gastroduodenal artery, runs to the left along the lower part of the greater curvature, and anastomoses with the left gastro-omental artery.

*Left gastro-omental artery: arises from the splenic artery and courses along the upper part of the greater curvature to anastomose with the right gastro-omental artery.

*Short gastric arteries (four to five): arise from the distal end of the splenic artery or its splenic branches and pass to the fundus of the stomach.

Question 19

Describe the Venous drainage of the stomach

Answer 19

The gastric veins parallel the arteries in position and course.
• The left and right gastric veins drain into the portal vein, the short gastric veins and left gastro-omental vein drain into the splenic vein, which joins the superior mesenteric vein (SMV) to form the portal vein.

•The right gastro-omental vein empties in the SMV.
•A prepyloric vein ascends over the pylorus to the right gastric vein.

Question 20

What is the clinical significance of the prepyloric vein?

Answer 20

Because this vein is obvious in living persons, surgeons use it for identifying the pylorus.

Question 21

Lymphatics of the stomach

Answer 21

Lymph from the superior two-thirds of the stomach drains along right and left gastric vessels to the gastric nodes;
•lymph from the fundus and superior part of the body of the stomach also drains along the short gastric arteries and left gastro-omental vessels to the pancreaticosplenic nodes.

Question 22

Nerve supply of the stomach

Answer 22

Nerve supply
•Anterior and posterior vagal trunks (T6-T9 or T10).
•Presynaptic sympathetic fibres reach celiac and other ganglia through greater splanchnic nerves.

Question 23

Why is the right phrenic nerve shorter than the left?

Answer 23

The right phrenic nerve is shorter than the left because it has a more direct path to the diaphragm. The phrenic nerves are a pair of nerves that originate from the cervical spine (C3-C5) and innervate the diaphragm, the right phrenic nerve has a more direct path to the diaphragm than the left phrenic nerve, which must curve around the aortic arch.

The left phrenic nerve descends through the thorax in front of the aortic arch, while the right phrenic nerve descends through the thorax in front of the superior vena cava and right atrium of the heart.

Question 24

Why would pain in the diaphragm cause a referred pain in the shoulder?

Answer 24

Pain in the diaphragm can sometimes cause referred pain in the shoulder due to the shared nerve supply between the diaphragm and the shoulder. The phrenic nerve, which provides sensory innervation to the diaphragm, also has sensory branches that supply the skin and tissues of the shoulder, particularly the C3 and C4 dermatomes.

When the diaphragm is irritated or inflamed, the pain signals can be transmitted along the phrenic nerve and also affect the sensory branches that supply the shoulder. This can result in the sensation of pain, discomfort, or even numbness in the shoulder region, which is known as referred pain.

Question 25

Describe the anterior abdominal wall

Answer 25

It covers a large area.
• It is bounded superiorly by the xiphoid process and costal margins,
• Posteriorly by the vertebral column, and
•Inferiorly by the upper parts of the pelvic bones.
• Its layers consist of skin, superficial fascia (subcutaneous tissue), muscles and their associated deep fascias, extraperitoneal fascia, and parietal peritoneum

Question 26

Describe the superficial fascia of the anterior abdominal wall

Answer 26

The superficial fascia of the abdominal wall (subcutaneous tissue of abdomen) is a layer of fatty connective tissue.
•It is usually a single layer similar to, and continuous with, the superficial fascia throughout other regions of the body.
•However, in the lower region of the anterior part of the abdominal wall, below the umbilicus, it forms two layers:
•a superficial fatty layer and a deeper membranous layer.

Question 27

Describe the Superficial layer of the superficial fascia

Answer 27

Superficial layer
•The superficial fatty layer of superficial fascia (Camper’s fascia) contains fat and varies in thickness .
•It is continuous over the inguinal ligament with the superficial fascia of the thigh and with a similar layer in the perineum

•In men, this superficial layer continues over the penis and, after losing its fat and fusing with the deeper layer of superficial fascia, continues into the scrotum where it forms a specialized fascial layer containing smooth muscle fibres (the dartos fascia).

• In women, this superficial layer retains some fat and is a component of the labia majora.

Question 28

Describe the deeper membranous layer of superficial fascia

Answer 28

•The deeper membranous layer of superficial fascia (Scarpa’s fascia) is thin and membranous, and contains little or no fat .
• Inferiorly, it continues into the thigh, but just below the inguinal ligament, it fuses with the deep fascia of the thigh (the fascia lata;).
• In the midline, it is firmly attached to the linea alba and the symphysis pubis.
• It continues into the anterior part of the perineum where it is firmly attached to the ischiopubic rami and to the posterior margin of the perineal membrane.

Question 29

Discuss the external oblique muscles

Answer 29

External oblique
• The most superficial of the three flat muscles in the anterolateral group of abdominal wall muscles.
•It is immediately deep to the superficial fascia.
•Its laterally placed muscle fibres pass in an inferomedial direction, while its large aponeurotic component covers the anterior part of the abdominal wall to the midline.
•Approaching the midline, the aponeurosis are entwined, forming the linea alba, which extends from the xiphoid process to the pubic symphysis.

Question 30

Associated ligaments of external oblique

Answer 30

• The lower border of the external oblique aponeurosis forms the inguinal ligament on each side .
• This thickened reinforced free edge of the external oblique aponeurosis passes between the anterior superior iliac spine laterally and the pubic tubercle medially .
• It folds under itself forming a trough, which plays an important role in the formation of the inguinal canal.

•Other ligaments are also formed from extensions of the fibers at the medial end of the inguinal ligament:
•the lacunar ligament is a crescent-shaped extension of fibers at the medial end of the inguinal ligament that pass backward to attach to the pecten pubis on the superior ramus of the pubic bone;
•additional fibers extend from the lacunar ligament along the pecten pubis of the pelvic brim to form the pectineal (Cooper’s) ligament.

Question 31

Describe the rectus sheath

Answer 31

Rectus sheath

•The rectus abdominis and pyramidalis muscles are enclosed in an aponeurotic tendinous sheath (the rectus sheath).
•Formed by a unique layering of the aponeuroses of the external and internal oblique, and transversus abdominis muscles

Question 32

Innervation of the anterior abdominal wall

Answer 32

anterolateral abdominal wall muscles:
T7 to T12 and L1 spinal nerves
•All terminate by supplying skin: nerves T7 to T9 supply the skin from the xiphoid process to just above the umbilicus;

•T10 supplies the skin around the umbilicus;
•T11, T12, and L1 supply the skin from just below the umbilicus to, and including, the pubic region;
•Additionally, the ilio-inguinal nerve (a branch of L1) supplies the anterior surface of the scrotum or labia majora, and sends a small cutaneous branch to the thigh.

Question 33

Superficial arterial supply of anterior abdominal wall

Answer 33

Superficially:
the superior part of the wall is supplied by branches from the musculophrenic artery, a terminal branch of the internal thoracic artery;

•the inferior part of the wall is supplied by the medially placed superficial epigastric artery and the laterally placed superficial circumflex iliac artery, both branches of the femoral artery.

Question 34

Deeper arterial supply of anterior abdominal wall

Answer 34

•At a deeper level:
• the superior part of the wall is supplied by the superior epigastric artery, a terminal branch of the internal thoracic artery;
•the lateral part of the wall is supplied by branches of the tenth and eleventh intercostal arteries and the subcostal artery;
•the inferior part of the wall is supplied by the medially placed inferior epigastric artery and the laterally placed deep circumflex iliac artery, both branches of the external iliac artery.

The superior and inferior epigastric arteries both enter the rectus sheath.
•They are posterior to the rectus abdominis muscle throughout their course, and anastomose with each other.
•Veins of similar names follow the arteries and are responsible for venous drainage.

Question 35

Briefly describe the course of the superior and inferior epigastric

Answer 35

The superior and inferior epigastric arteries both enter the rectus sheath.
•They are posterior to the rectus abdominis muscle throughout their course, and anastomose with each other.

Question 36

Describe the lymphatic drainage of the anterior abdominal wall

Answer 36

•Lymphatic drainage of the anterolateral abdominal wall follows the basic principles of lymphatic drainage: superficial lymphatics above the umbilicus pass in a superior direction to the axillary nodes, while drainage below the umbilicus passes in an inferior direction to the superficial inguinal nodes;
•deep lymphatic drainage follows the deep arteries back to parasternal nodes along the internal thoracic artery, lumbar nodes along the abdominal aorta, and external iliac nodes along the external iliac artery.