Abdominal wall and peritoneum Flashcards
What is the superior boundary of the abdo?
The diaphragm and the inferior thoracic aperture. The abdo extends up quite high to about rib 5 so the stomach and liver sit up behind the ribs.
What is the inferior boundary of the abdo?
The inguinal ligament, iliac crests and the pelvic inlet. The abdo extends quite deep into the pelvis so alot of the abdo contents are sitting down low.
What is the anterior and lateral boundary of the adbo?
The abdominal wall muscles. (rectus abdominis, trasnverse abdominis, inner oblique, outer oblique).
What is the posterior boundary of the abdo?
The lumbar vertebrae and several back muscles (quadratus lumborum, psoas major) and the abdominal wall muscles.
From skin inwards what are the layers of the abdominal wall?
Skin, superficial fascia (campers and scarpas), muscles (ext oblique, int oblique, transversalis abdominis), deep fascia (transversalis fascia and extraperitoneal fascia), parietal peritoneum
What is the difference between campers and scarpas fascia and what is the difference in their distribution?
Campers (fatty) fascia is much thicker and yellower compared to scarpas (membranous) fascia which is quite thin and slightly orange in colour.
This division of the superficial fascia into these two layers only occurs below the umbilicus. Above the umbilicus it is very similar to the rest of the body.
What direction do the fibres run in the external oblique and internal oblique muscle layers?
external oblique = “hands in pockets”, the fibres run infero-medial (downwards toward the midline).
internal oblique = supero-medial (upwards toward the midline)
What is the nerve supply to all of the abdominal wall muscles?
Anterior rami of thoracic spinal nerves
What is the origin and insertion of rectus abdominis muscles? What is its action?
Origin = the pubic area of the pelvis (pubic tubercle, crest and symphysis)
Insertion = the costal cartilages of ribs 5-7
Action = flex the trunk, support abdo wall, act as a secondary respiratory muscle to help with forced expiration
What is the origin, insertion and action of the external oblique muscle?
Origin = ribs 5-12
Insertion = iliac crest and the linea alba (centre indentation of the abbs that girls have) via the very big aponeurosis
Action = When both sides of the external oblique contract it will flex the trunk forward. When only one side fires it will flex/bend the trunk to the opposite side of the pull of the muscle.
What is the origin, insertion and action of the internal oblique muscle?
Origin = thoracolumbar fascia, inguinal ligaments and the iliac crests
Insertion = ribs 9-12
Action = if both sides of the internal oblique fire then they will act to flex the trunk. If only one side fires then it will flex/turn the trunk to the same side as the side of contraction.
What is the origin, insertion and action of the transversalis abdominis muscle?
Origin = Thoracolumbar fascia, iliac crest, inguinal ligment, costal cartilages of ribs 7-12
Insertion = linea alba (midline)and pubic crest (middle of pelvic bones) by aponeurosis
Action = supports abdo wall
What is the rectus sheath?
The large aponeurosis formed by the transverse abdominis, and ext and int oblique muscles of the abdo wall. The rectus sheath runs both above and below of the rectus abdominis muscle, wrapping around from the sides of the body.
What is the arcuate line?
The arcuate line is approx halfway between the umbilicus and the pubic symphysis and is where there is a change in the rectus sheath. At the arcuate line the posterior wall of the rectus sheath stops. (above this line the posterior wall of the rectus sheath was formed by the transveralis muscle apo and half of the int oblique muscle apo).
This means that inferior to the arcuate line the abdo wall is relatively weak as the only thing supporting underneath it is the transversalis (deep fascia) and the parietal peritoneum. This allows arteries to pass underneath it.
What is the blood supply to the anterior abdominal wall?
The superior epigastric artery (comes from the internal thoracic) and the inferior epigastric artery (comes from the external iliac) anastomose together after travelleing under the rectus abdominis muscle through the rectus sheath.
