Layers of Anterolateral Abdominal Wall going from superficial to deep.
Skin, Camper's Fascia, Scarpa's Fascia, 3 skeletal muscle layers, transversalis fascia, extraperiotneal fat, parietal peritoneum, abdominal organs
What is significant about scarpa's fascia?
It is only found in the abdomen and is the thinner and more fibrous than camper's fascia.
What is significant about extraperitoneal fat?
It helps up located the parietal peritoneum surgically because the parietal peritoneum is directly below it. This layer separates the transversalis fascia from the parietal peritoneum.
What are the abdominal wall muscles? (4)
Three flat muscles: External Oblique, Internal Oblique, and transversus abdominus
One vertical muscle: Rectus abdominis
Insertion: Costal cartiliages and xiphoid processes
Action: flexion of trunk
*four tendious insertions into supericial division in thin/very fit people these are the superifical tendons we see (i.e. six pack)
* fibers run vertically, 3X as long as wide
- midline is the pubic synthesis
- fivers run at angle (why we call them oblique)
- fiver run downwards and inward
- broad flat sheet of muscle
External Oblique Muscles
Origin: Ribs and costal cartilages
Insertion: Iliac crest (anterior superior iliac spine)
- Most Superficial muscles
- inguinal ligament part of obliques,
- fibers weave together so that those of right are superficial on right and deep on left - this happens at the aponeurosis and forms a continuous band
Origin: Iliac Crest
- inferior = pubis
- middle = mid line
they are organized into muscle and CT, CT in middle to get a seam
Origin: thoracolumbar fascia, iliac crest
- lower fibers come from inferior surface of inguinal ligament
Insertion: transverse on mid line in aponeurosis which contributes to formation of rectus sheath
Action: compresses and supports abdominal viscera
- made of abdominal aponeurosis of the flat abdominal muscles (obliques and transverse abdominis)
- compartment of the rectus abdominis muscles, as well as superior and inferior epigastrics
- differs in upper and lower abdomen
- white mid line of the abdomen separating bilateral rectus abdominis sheaths
- directly touches the external oblique aporneurosis
- in late pregnancy can separate and turn into a dark purple line due to edema formation
Explain rectus sheath in the upper 3/4s of the abdomen.
The aponeurosis of the external and internal obliques join at the rectus abdominis and make up the superior border. The deep border is made of the aponeurosis of the internal obliques and the transverse abdominis which fuse and then travel beneath the rectus abdominis. All join up at the linea alba.
Explain rectus sheath in the upper 1/4s of the abdomen.
The aponeurosis of the internal obliques and transverse abdominis travel superficially over the rectus abdominis and join at the linea alba. *The external obliques don't exist here and no aponeurosis travel deep.
Which layer is always deep to the rectus abdominis and does contribute to the aponeurosis formation around it?
What nerves supply sensory innervation of the skin over the anterior abdominal wall?
The ventral rami of the lower 5 intercostal nerves (T7-11), subcostal nerve (T12), and the iliohypogastric and ilioinguinal nerves (L1).
What gives this region arterial blood supply?
The superior and inferior epigastric arteries as well as the intercostal arteries. These run deep to the surface and run the length of the muscle.
Where does lymph from skin above the umbilicus (back and upper limbs) drain?
Into the axillary nodes
Where does lymph from below the umbilicus (back, pelvis, perineum, and lower limbs) drain?
Into the superficial inguinal nodes
What is unique about the lower 1/4 of the deep rectus abdominus?
There are no aponeurosis there - it is exposed below the arcuate line.
What are the basic functions of the abdominal muscles?
unilateral - lateral flexion (bend side to side)
bilateral - flexion and rotation
What are the less obvious functions?
- stabilization of trunk during physical effort (valsalva's maneuver)
- forceful expiration
- coughing and sneezing
- urination and dfecation
- labor and delivery (females)
How do muscles aid with the less obvious functions?
1. muscles decrease abdominal cavity volume and increase pressure
2. abdominal organs increase pressure in thorax and pelvis
What is extravasation of urine?
- urine leakage up into abdominal wall btw scarpis and external abdominal oblique (continuous space)
- urine can travel up as far as the rib cage
What is prune belly syndrome?
Absence of some or all anterior abdominal muscles, causes abdominal organs to spill out and make a sack like structure. Treatment is to take an anterior thigh muscle and attach it to the xiphoid process. Can then teach to laugh, cough and respiration with it.