Posterior Abdominal Wall Flashcards
Thwart are the walks of the abdominal period”v8c cavity?
The abdominal and pelvic cavities are continuous
Upper boundary- thoraco-abdominal diaphragm
Lower boundary- pelvic diaphragm
Pelvic inlet- the division between the abdominal and pelvic cavities
Parietal peritoneum- Lines the abdominal wall and the pelvic organs serving as an additional separation
What is the diaphragm?
Muscular and tendinous separation between the thorax and abdomen
-Lined with peritoneum (inferiorly), except for the area superior to the bare area of the liver
Diaphragm as a muscle changes size of the thoracic cavity to facilitate airflow of the lungs during breathing
What are the three large openings of the diaphragm ?
Inferior vena cava T8 vertebral level
Esophagus T10 vertebra level
Aorta T12 vertebral level
What is the blood supply of the diaphragm?
- superior and inferior phrenic arteries
- musculophrenic arteries
- pericardioohrenic arteries
What is the innervation of the diaphragm?
Phrenic nerves (C3,4,5)
Where does the inferior vena cava enter the diaphragm?
Caval hiatus(T8)
Where does the esophagus enter the diaphragm?
Esophageal hiatus (T10)
Along with esophagus, anterior and posterior vagal trunks
What enters the diaphragm: through the median articulate ligament?
At T12
Aorta and thoracic duct
What is the function of the psoas major?
Action: flexes hip
What is the innervation of the psoas major?
Innervated by ventral rami of L1-3
O/I vertebral bodies & transverse processes T12-L5 to lesser trochanter
What is the function of the Quadratus lumborum?
Depresses & stabilizes rib 12, lateral bending (lateral flexion)
What is the innervation of the Quadratus lumborum?
Innervated by ventral rami of T12-L4
O/I transverse process of L5, iliac crest and iliolumbar ligament to transverse processes of L1-4 and rib 12
What is the action of the iliac?
Action: flexion of hip
What is the innervation of the iliacus?
Innervated by femoral nerve
O/I iliac fossa and upper portion of lateral sacrum to lesser trochanter
What is the location and function of the lumbar plexus?
The nerve supply of the posterior abdominal wall, pelvic walls and floor and lower limb are closely related
The lumbar plexus serves the abdomen, anterior and medial thigh
The sacral plexus receives a contribution from the lumbar plexus- lumbosacral trunk
-The sacral plexus supplies the pelvic muscles, gluteal region and posterior lower limb
What nerves are applied to the lumbar plexus?
Iliohypogastric nerve
Ilioinguinal
Genitofemoral
Lateral femoral cutaneous
Femoral
Obturator
What is the function of the iliohypogastric nerve of the lumbar plexus?
T12-L1: iliohypogastric: internal oblique transversus muscles, skin above pubis (suprapubic) and gluteal region
What is the function of the ilioinguinal nerve of the lumbar plexus?
L1: ilioinguinal:Internal oblique- transversus muscles, skin over upper medial thigh, anterior scrotum and labia majora
What is the function of the genitofemoral nerve of the lumbar plexus?
L1-L2
Genital branch: supply cremaster and scrotum
Femoral branch: skin of the femoral triangle
What is the function of the lateral femoral cutaneous nerve of the lumbar plexus?
L2-3: lateral femoral cutaneous: skin of anterior and lateral thigh
What Is the function of the femoral nerve of the lumbar plexus?
L2-L4: femoral nerve: skin of the anterior thigh, medial part of thigh, hip and knee joints. Quadriceps femoris, pectineus, sartorius muscles. (Anterior muscle compartment of thigh)
What is the function of the obturator nerve of the lumbar plexus ?
L2-4: obturator: skin on medial side of thigh, adductor muscles (medial muscle compartment on thigh)
Describe the cremaster Reflex
Genital branch of the genitofemoral nerve supplies the cremaster muscle-this is the efferent limb of the cremaster reflex arc
Ilioinguinal nerve supplies the upper medial portion of the thigh -this is the afferent limb of the cremaster reflex arc
Femoral branch of the genitofemoral nerve supplies the area over the femoral triangle
Lightly touching the skin over the medial side of the upper thigh invokes the cremaster reflex-testis is pulled upward
Strong in infants
What are the afferent and efferent pathways of the cremaster reflex?
Afferent pathway: ilioinguinal nerve (L1)
Efferent pathway: Genital branch of the genitofemoral nerve(L1,L2)
Describe the significance of the abdominal aorta
Continuation of thoracic aorta
Passes through the diaphragm at T12 vertebral level
Gives paired and unpaired branches to both the abdominal viscera and abdominal wall
Bifurcate at L4 into the common iliac arteries
Common iliac arteries divide into internal and external iliac arteries
What is the significance of internal and external iliac arteries ?
Internal iliac artery supplies the pelvis and gluteal region
-umbilical (partially oblitered), superior vesicle, middle rectal, superior gluteal, inferior gluteal, internal pudendal, lateral sacral, obturator, iliolumbar
External iliac becomes the femoral artery as it passes deep to the inguinal ligament and supplies the lower limb
Describe the common iliac veins
Junction of the external and internal iliac veins at the pelvic inlet
The internal iliac vein receives blood from the pelvic organs, pelvic wall and gluteal region
The external iliac vein receives blood from the lower anterior abdominal wall and lower limb
Where is the inferior vena cava?
Starts at L5 vertebra with the junction of the two common iliac veins
The tributaries to the IVC do not correspond exactly to the branches of the aorta
Where does the inferior vena cava DIRECTLY get blood from?
- lumbar
- right inferior phrenic
- renal
- right suprarenal
- right gonadal
- hepatic
- common iliac vein
Where does the inferior vena cava INDIRECTLY receive blood?
It receives blood indirectly from the:
-left inferior phrenic (via renal veins)
- femoral and lower limb veins(via external iliac)
- anterior abdominal wall (via external iliac)
- pelvic organs(via internal iliac)
- left gonadal (via left renal)
- left suprarenal (via renal)
Where do the azygos veins receive blood from?
Receives blood from the posterior walls of the thorax and abdomen into the superior vena cava
What is the azygos system of veins formed by?
Formed by the union of the ascending lumbar veins with the right subcostal veins at the level of the 12th thoracic vertebra, ascending in the posterior mediastinum , and arching over the right main bronchus posteriorly at the root of the right lung to join the superior vena cava
What is the sosignificance of the azygos veins?
A major tributary of the azygos system is the hemizygos vein, a similar structure on the opposite of the vertebral column.
It also creates a cavo-caval anastomosis by offering an alternative, collateral blood flow from the lower half of the body to the superior vena cava, bypassing the inferior vena cava
Summarize azygos system of veins
Ascending lumbar veins receive blood from lumbar veins and drain into azygos or hemiazygos veins on to superior vena cava
Summarize internal thoracic veins
Continuous with superior and inferior epigastric veins and thus connects external iliac vein with Subclavian vein on to right atrium eventually
Summarize the Axillary vein
Superficial epigastric veins which drain into the axillary vein which becomes Subclavian, brachiocephalic to form superior vena cava it’s brachiocephalic vein from contralateral vein
Summarize the obstructed blood flow of IVC
Veinous drainage from the abdominal and pelvic walls and pelvic organs is via the inferior vena cava.
Pathologies can result in obstruction of the IVC
Several alternative drainage pathways are available. The alternative pathways may increase the size of the vessels. If these are superficial vessels they may become visible under the skin
Summarize abdominal and lymphatics
Lymphatics from the posterior abdominal wall drain into the lumbar (lateral aortic) nodes
These eventually drain into the cisterna chyli, a large fluid filled sac which collects lymph of the entire lower part of the body
What are cisterna chyli?
A retro-peritoneal structure. In humans, it is located posterior to the abdominal aorta on the anterior aspect of the bodies of the first and second lumbar vertebrae(L1 and 2)
How does abdominal lymphatics & cisterna chyli?
It forms the beginning of the primary lymph vessel, the thoracic duct, which transports lymph and chyle from the abdomen cavity via the aortic opening of the diaphragm to the junction of left Subclavian vein and left internal jugular vein
-It receives lymph from the intestinal trunk and the lumbar lymphatic trunks
Where does lymph posterior abdominal wall drain to?
Lymph from the posterior abdominal wall drains into the lumbar (lateral para aortic) lymph nodes which eventually drains into the cisterna chyli and continues as the thoracic duct
