Flashcards in Lecture 9 DA Deck (34)
What are the two fascia of the skin in the abdomen?
Camper's fascia - more fatty and superficial
Scarpa's fascia - more membranous and deep
How is the perotineum of the abdomen different to the thoracic perotineum?
It has more than one site where it leaves the abdominal wall. This is known as mesentery (like the pulmonary ligament).
What structures does the abdominal muscles attach to?
To the costal margin superiorly.
To the iliac crest, ASIS and pubic crest/tubercle inferiorly.
How do the three abdominal muscle layers attach to the costal margin?
The most superficial overlaps with the costal margin.
The middle layer is edge-to-edge with the costal margin.
The deepest underlaps the costal margin.
How do the abdominal muscles change as you move medially?
They are fleshy laterally, and aponeurotic medially.
Describe the three layers of abdominal muscles.
Superficial most - external oblique, front pockets muscle
middle - Internal oblique, back pockets muscle
deepest - transversus abdominus, runs horizontally
What is the linea alba?
The abdominal muscles are aponeurotic medially, and this contributes to the linea alba, found at the midline.
Where does the external oblique attach inferiorly?
To the anterior half of the iliac crest, to the ASIS, and to the pubic crest.
It has a free inferior edge, bordered by the inguinal ligament.
Where does the internal oblique attach inferiorly?
To the iliac crest, to the ASIS, and to the lateral two thirds of the inguinal ligament.
Free inferior edge turns inward, providing attachment of lowermost fibres to the inguinal ligament.
Do the lowermost fibres of the internal oblique contribute to the linea alba?
No, they arch upward and back down to attach to the pubic crest.
What is the relationship between the transversus abdominus muscle, and the diaphragm?
They are continuous with each other/on the same plane.
Where does the transversus abdominus muscle attach inferiorly?
To the iliac crest, to the ASIS, and to the lateral third of the inguinal ligament. Fibres also arch upward and down to the pubic crest as with internal oblique. The two form a conjoined tendon, which inserts to the pubic tubercle.
Where does the rectus abdominus muscle insert and attach?
It arises from the pubic crest, and inserts to the costal margin, overlapping it. It attaches to ribs 5, 6, & 7.
Describe the structure of rectus abdominus, and why its beneficial.
It has transverse aponeuroses, called tendinous inscriptions. There are typically 3:
One at the umbilicus
One between at the xiphisternum
One between umbilicus and xiphisternum
This makes the muscle much stronger.
What else is formed alongside the linea alba?
The rectus sheath. As the aponeuroses of the internal/external oblique and transversus abdominus travel medially, they travel anterior and posterior to the rectus abdominus, enveloping it in a thick sheath before forming the linea alba.
Describe the aponeurotic contributions to the rectus sheath.
The external oblique moves anteriorly, while transversus abdominus moves posteriorly. The internal oblique has both anterior and posterior sheaths, but is mostly edge-to-edge with the rectus abdominus.
Halfway between the umbilicus and the pubic crest, the posterior sheath disappears, and all abdominal muscle aponeuroses contribute entirely to the anterior sheath.
The border formed by the posterior sheath is called arcuate line.
What is the acruate line?
It is the border of the posterior rectus sheath.
Where do nerves run within the abdomen?
They run between the internal oblique, and the transversus abdominus. They are ventral rami segmental nerves.
What landmarks are found at T10 and L1?
T10 - umbilicus
L1 - groin
What is the arterial supply to the abdomen, and where do they originate?
Superior epigastric artery, comes from above via the internal thoracic/mammary artery.
Inferior epigastric artery, comes from below via the external iliac artery.
How does the internal thoracic/mammary artery contribute to abdominal arterial supply?
As it runs down the sternum, it branches into the musculophrenic artery and superior epigastric artery.
Musculophrenic artery continues along the costal margin, and gives off segmental arteries.
Superior epigastric artery travels downward to meet with the inferior epigastric artery.
What is the superficial epigastric artery?
Unrelated to abdominal blood supply, arising from the femoral artery, up towards the umbilicus.
Describe the veinous system of the abdomen.
It has a superior and inferior epigastric vein, which follow their respective arteries.
Note, they drain partly to the systemic circulation and partly to the hepatic circulation through the portal system, via the paraumbilical vein.
What is the inguinal ligament?
It is the free thickened border of the external oblique.
What is the lacunar and pectineal ligament?
The lacunar ligament is a crescent-shaped extenstion of the inguinal ligament inward.
The pectineal ligament is close to the lacunar ligament, which travels along the pectineal line.
Where do the testis develop? Why is this not ideal?
They develop very deep, just outside the perotineum, surrounded by extraperotineal fat. This is too warm to produce viable sperm, so it migrates downward to the scrotum.
Do ovaries descend as the testis does?
Yes, but they stop at the pelvis.
What is the inguinal canal?
It is the path taken by the testis through the anterior wall.
What is the deep/internal inguinal ring, and where is it found?
It is a deficiency found at fascia transversalis, the deepest fascia. It is found a finger's breadth above the inguinal ligament.