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.
What is the venous supply to the anterior abdominal wall?
The upper aspect of the abdo wall is drained by thoracoepigastric veins which drain up to the axillary vein. The lower aspect of the abdo wall is drained by the superifical epigastric veins which drains down to the femoral vein.
What is the nerve supply to the anterior abdo wall?
The lower 6 intercostal nerves (T7-T12) (both lateral cutaneous branches and anterior cutaneous branches) as well as iliohypogastric nerves (at the level of L1).
These nerves travel in the neruovascular plane (between the inner oblique and the transverse abdominis muscle).
What are the dermatomes to the anterior abdo?
The dermatomes wrap around the body at the level of each rib,
Describe the lymphatic drainage of the abdomen by area eg superior anterior
superior anterior and posterior = drainage to axillary nodes
inferior anterior and posterior = drainage to superficial inguinal nodes
What is the gut tube suspended by and what peritoneal layer forms this?
The mesentary which is formed by the back folding of the visceral peritoneum.
What is the nervous supply to the parietal and visceral peritoneum?
Parietal peritoneum = nervous supply by somatic nerves, phrenic nerve and obturator nerve. It is sensitive to pain, temperature, touch and pressure
Visceral peritoneum = nervous supply by ANS nerves (no somatic supply) hence it is only sensitive to stretch eg can sense when you’ve eaten too much
What does intraperitoneal mean and what parts of the abdomen are within this?
Intraperitoneal means the organs are completely contained by visceral peritoneum and are suspended by mesentery
This includes the stomach, liver, gall bladder, proximal duodenum, jejunum, ileum, appendix, transverse and sigmoid colon
What does retroperitoneal mean and what parts of the abdo are within this?
Retroperitoneal means the organs are sitting between the visceral peritoneum and the body wall
This includes the kidneys, pancreas, distal part of duodenum, ascending and descending colon, upper 2/3 of rectum
