What structures contribute to forming the posterior wall of the abdomine?
- Bone: Lumbar Vertabrae, Sacrum, Wings of Ilium, and ribs
- Muscles: Psoas major and minor, quadratus lumborum, iliacus
What is another name for the pelvis? What bones fuse to form it? What structures form the pelvic girdle, how do they connect?
- The os coxa,
- the ilium, ischium, and pubis.
- Girdle: Sacrum, 2 os coxa, articular surface of the os coxa articulate with the sacrum and the pubic
What are the muscles of the posterior abdominal wall?
- Psoas major
- Psoas Minor
- Quadratus lumborum
Psoas Major OINA
- O: transverse processes, bodies, and intervertebral discs of T12-L5
- I: Lesser trochanter with iliacus
- N: ventral primary rami of L2-L4
- A: Flx thigh, lateral flexion of trunk and flexion of trunk (only true flexion of trunk when lying prone) otherwise it is a eccentric conctraction of the posterior muscles.
Psoas Minor OINA
- O: bodies of T12 and L1 and the disc in between
- I: Pubic bonde
- N: Ventral rami of L1
- A: Flx pelvis and vertebral column
- O: Iliac Fossa
- I: lesser trochanter with the psoas major
- N: Femoral n.
- A: Flexion of the thigh
Quadratus Lumborum OINA
- O: Iliac crest, iliolumbar ligament, xverse process of lover lumbar vertebrae
- I: Rib 12, xverse process of upper lumbar vertebrae
- N: subcostal (T12) upper lumbar ventral primary rami
- A: Lat flx of trunk, extend vertebral column, elevate hip, stabilize 12 rib against inspiration. (primarily just stabilization of lumbar spine)
What is the lumbosacral plexus?
It's the collective name given to the lumbar (L1,2,3, and part of L4) and sacral plexus (L4-S4).
What are the roots and nerves of the lumbar plexus?
- Roots: L1,2,3 and part of 4
- Iliohypogastric - L1
- Ilioinguinal - L1
- Genitofemoralo - L1, L2
- Lateral femoral cutaneous - L2, L3
- Femoral - L2,3,4
- Obturator - L2, L3, L4
What are the roots and nerves of the sacral plexus?
- Superior gluteal - L4, L5, S1
- Inferior gluteal - L5, S1, S2
- Sciatic - L4, L5, S1, S2, S3
- Pudendal - S2, S3, S4
- Twigs of the piriformis - S1, S2, S3, S4
- Nerve to the obturator internus - L5, S1, S2
- Nerve to the quadratus femoris - L4, L5, S1
What is the arterial supply for the posterior wall?
- Abdominal Aorta (descending aorta becomes the abdominal aorta when it passes through the diaphragm and becomes the abdominal aorta)
- It divides at the level of L4 vertebra into right and left common iliac ateries.
- The common iliac arteries divide into the internal (supplies the viscera of the pelvic cavity) and external (passes under the inguinal ligament and enters the anterior compartment of the thigh, it changes names to the femoral artery when crossing under the ligament ) iliac arteries.
- The femoral travels below the sartorius in the subsartorius or hunters canal.
- The inferior epigastric artery arises from the external iliac artery before it enters tje anterior thigh compartment. It supplies the inferior aspect of the anterior abdominal wall.
What is the venous supply of the abdominal cavity?
- Inferior vena cava. returns blood from lower extremity, ant. abdominal wall and adbom pelvic viscera.
- Arises at L5 vertebra from the union of the common iliac veins.
- Ascends through the vena cava foramen in the diaphragm and continues to the heart.
What is the diaphragm?
It is a musculotendinous partition separating the thoracic and abdominal cavities. It is also the major muscle of respiration.
What are the parts of the diaphragm?
- Central tendon (boomerang shape)
- Peripheral muscular portion:
- Sternal portion: fibers from xiphoid to tendon
- Costal portion: from internal surface of lower six ribs and costal cartilage and lateral and medial arcuate ligamnets to ligament
- Lumbar portion: Fomr lumbar vertabra in for of right and left crus. Right cru from L1-3 and IVD, Left from L12 nad IVD.
What are the openings in the diaphragm?
- Sternocostal hiatus: passage of the superior eopigastric vessels and some lymphatics
- Foramen for the inferior vena cava: passage for the inferior vena cava and right phrenic nerve
- Esophageal hiatus: Pasage for the esophagus and vagal trunks
- Aortic Hiatus: passage for the aorta and thoracic ducts
- Sympathetic trunk passes posterior to the medial arcuate ligament