The abdomen

Describe the 4 quadrant pattern

1. The horizontal transumbilical plane passes through the umbilicus and the intervertebral disc between vertebra LIII and LIV and intersecting with the vertical medial pane divides the abdomen into 4 quadrants

What are the 4 quadrants ?

The upper right, upper left, right lower and left lower quadrants

Describe the nine region pattern

• 2 horisontal and 2 vertical planes

• The superior horizontal plane (subcostal plane) immediately inferior to the costal margin which places it at the lower border of the costal cartilage of rib X

• Inferior horizontal plane (intertubercular plane) connects the tubercles of the iliac crests and passes through the upper part of the body of vertebra LV

• Vertical plane passes from the midpoint of the clavicles inferiorly to a point midway between the anterior superior iliac spine and pubic symphysis

What are the nine regions?

• The epigastric

• The 2 hypochondriac regions

• The umbilical region

• The 2 lateral regions of the abdomen

• The hypogastric region

• The 2 inguinal regions

Describe the superficial fascia

• Layer of fatty connective tissue

• Usually a single layer similar to and continuous with the superficial fascia throughout other regions of the body

• On the lower region of the anterior part of the abdominal wall (below umbilicus) forms 2 layers a superficial fatty layer and a deeper membranous layer:

1. Superficial layer

2. Deep layer

What are the functions of the muscles of the abdominal wall ?

1. Maintenance of many normal physiological functions

2. Keep the abdominal viscera within abdominal cavity

3. Protect the viscera from injury

4. Help maintain the position of the viscera in the erect posture against the action of gravity

What does the contraction of the abdominal muscles do?

Assist in both quiet and forced expiration by pushing the viscera upward and in coughing and vomiting

—> also involved in any action that increases intra-abdominal pressure, including parturition, micturition and defecation

What is the linea alba?

It formed by intertwined aponeuroses, and it extends form the xiphoid process to the pubic symphysis

By what is the inguinal ligament formed?

It is formed in th lower border of the external oblique by the aponeurosis

Where does the inguinal ligament pass through ?

Between the anterior superior iliac spine laterally and the pubic tubercle medially

—> it folds under itself forming a trough which plays and important role in the formation of the inguinal canal

Describe the lacunar ligament

• Crescent shaped extension of fibers at the medial end of the inguinal ligament

• passes backwards to attach to the patten pubis on the superior ramus of the pubic bone

Describe the pectineal ligament

• Formed by additional fibers that extend from the lacunar ligament along the pecten pubis of the pelvic brim

Where does the name transversus abdominis come from?

From the direction of most of its muscle fibers

Describe the transversalis fascia

• Layer of deep fascia that covers each of the 3 flat muscles

• It is unremarkable except of the layer deep to the transversus abdominis (transversalis fascia) which is better developed

• —> become parietal fascia

What is the rectus sheath ?

It is an aponeurotic tendinous sheath formed by an unique layering of the aponeuroses of the external and internal oblique and transversus abdominis muscles

—> it encloses the rectus abdominis and the pyramidalis muscles

Where is the extraperitoneal fascia ?

Deep to the transversalis fascia

What is the extraperitoneal fascia ?

• Layer of connective tissue

• Separates the transversals fascia from the peritoneum

• Contains various amounts of fat

• Lines the abdominal cavity but is also continuous with a similar layer lining the pelvic cavity

• Abundant on the posterior abdominal wall

Where is the peritoneum ?

Deep to the extraperitoneal fascia

What is the peritoneum ?

• Thin serous membrane that lines the walls of the abdominal cavity and also reflect onto the abdominal viscera

In what is the peritoneum divided ?

Into

1. Visceral peritoneum - covering the viscera

2. Parietal peritoneum - lining the walls

What happens with the parietal peritoneum ?

It forms a sac

What is the difference in the abdominal sac in men and women ?

1. Men have the sac enclosed

2. Women - have 2 openings where the uterine tubes provide a passage to the outside

   —> This sac is called the peritoneal cavity

By what are the skin, muscles and parietal peritoneum of the anterolateral abdominal wall supplied?

By the T7 to T12 and L1 spinal nerves

What do the anterior rami of the spinal nerves do ?

They pass around the body, from posterior to anterior, in an inferomedial direction

—> They give off a lateral cutaneous branch and end as an anterior cutaneous branch

What do the intercostal nerves do (T7-T11) ?

They leave the intercostal spaces, passing deep to the costal cartilages and continue onto the anterolateral abdominal wall between the internal oblique and transversus abdomen muscle

—> Reaching the lateral edge of the rectus sheath they enter the rectus sheath and pass posterior to the lateral aspect of the rectus abdomen muscle

—> preaching the midline an anterior cutaneous branch passes through the rectus abdominis muscle and the anterior wall of the rectus sheath to supply the skin

What do the spinal nerves T12 do (subcostal nerve) ?

It follows a similar course as the intercostals

Which other nerves also follow a similar course as the intercostal nerves ?

Branches of the L1 (ilihypogastric nerve); which originates from the lumbar plexus

—> But it then deviates form this pattern near their final destination

In what terminate all nerves from T7-T12 and L1?

In supplying skin:

1. T7-9 supply the skin from the xiphoid process to just above the umbilicus

2. T10 supplies the skin around the umbilicus

3. T11, T12 and L1 supply the skin from just below the umbilicus to and including the pubic region

4. The ilioinguinal nerve (branch of L1) supplies the anterior surface of the scrotum, labia major and sends a small cutaneous branch to the thigh

By what is the superior part of the wall supplied?

By branches from the musculophrenic artery, a terminal branch of the internal thoracic artery

By what is the inferior part of the wall supplied?

By medially placed superficial epigastric artery and the lateral placed superficial circumflex iliac artery → branches of the femoral artery

By what is the superior part supplied at a deeper level?

By the Superior epigastric artery a terminal branch of the internal thoracic artery

By what is the lateral part supplied at a deeper level?

By branches of the tenth and eleventh intercostal arteries and the subcostal artery

By what is the inferior part supplied at a deeper level?

By the medially placed inferior epigastric artery and the laterally placed deep circumflex artery both branches of the external iliac artery

What do the superior and inferior epigastric arteries do?

They enter the rectus sheath they are posterior to the rectus abdominis muscle throughout its course and anastomose with each other

What is the peritoneum ?

• It is a thin membrane that lines the walls of the abdominal cavity and covers much of the viscera

What is the peritoneal cavity divided into ?

1. The greater sac

2. The omental bursa (lesser sac)

Describe the peritoneal ligament

• Consists of 2 layers of peritoneum that connect 2 organs to each other or attache an organ to the body wall and may form part of the omentum