Abdominal Aorta And Ivc

GREAT VESELS OF THE ABDOMEN

Abdominal Aorta The thoracic aorta passes through the aortic hiatus to become the abdominal aorta and extends between the T12 – L4 vertebra levels Abdominal aorta terminates at the aortic bifurcation by giving its two terminal branches, right and left common iliac arteries Branches of the aorta are classified as unpaired and paired branches

Abdominal aorta  Can

be compressed against vertebral column in children and thin adults at L4 level.

Unpaired branches • Celiac trunk – Left gastric artery • Esophageal branches

– Splenic (lienal artery) • • • •

Short gastric aa Posterior gastric Pancreatic branches Left gastroepiploic artery

– Common hepatic artery • Gastroduodenal artery – Superior pancreaticoduodenal artery – Right gastroepiploic artery

• Proper hepatic artery – Right gastric artery – Right and left hepatic aa

• Middle sacral artery

• Superior mesenteric artery – Inferior pancreaticoduodenal artery – Jejunal branches – Ileal branches – Ileocolic artery • Anterior and posterior caecal aa • Appendicular artery

– Right colic artery – Middle colic artery

• Inferior mesenteric artery – Left colic artery – Sigmoid aa – Superior rectal artery

(abdominal)Aortic aneurysm

• This angiogram picture shows a typical aortic aneurysm. As the aneurysm gets larger, the risk of rupture increases greatly.

Clinical note   As

aorta lies posterior to the pancreas and stomach, tumors of these organs may transmit the pulsations of the aorta, mimicking an aneurysm

INFERIOR VENA CAVA •The two common iliac veins join at L5 to form IVC. •IVC pierces(passes through) the diaphragm at T8 level •Receives all the systemic veins from the abdomen except left gonadal and left supra renal veins

Tributaries  The

two common iliac veins  Right gonadal vein  Both renal veins  Right suprarenal vein  Inferior phrenic veins  Hepatic veins

•In some instances the vena cava crosses anterior to (instead of posterior to) the ureter.It is called •pre-ureteric vena cava and may cause • ureteric obstruction

Extensive anastomoses among the caval, azygos, and vertebral systems provide multiple routes for the return of blood to the heart. In effect, the azygos and vertebral systems bypass the caval system.

POSTERIOR ABDOMINAL WALL Bears the following structures 

Five lumbar vertebrae and intervertebral discs between them



Posterior abdominal wall muscles; psoas, quadratus lumborum, iliacus, transverse and oblique abdominal muscles



Part of diaphragm



Fascia, including the thoracolumbar fascia



Lumbar plexus and its branches



Fat, lumbar sympathetic trunks, vessels (i.e. aorta, IVC)

Posterior abdominal wall

 The

psoas sheath, attached to the lumbar transverse processes and bodies, allows the spread of infection (e.g., a tuberculous abscess from a vertebral body) into the thigh (psoas abscess).

 L1

Lumbar plexus

 L2  L3  L4  L5  L1

gives rise to the iliohypogastric and ilioinguinal nerves.  L1 + L2 gives rise to the genitofemoral nerve  L2 + L3 gives rise to the lateral femoral cutaneous  L2 + L3 + L4 give rise to the femoral and obturator nerves  L4 + L5 give rise to the lumbosacral trunk which joins sacral nerves to form the sacral plexus.

DIAPHRAGM (dia = in between, phragma = partition)  Formed

of skeletal muscles

 Muscle

fibers converge at the center to form the central tendon

 Lies

between the thoracic and abdominal cavities

 The

chief muscle of inspiration

DIAPHRAGM (continued)

Parts of the diaphragm  Central  Right

tendon (has no bony attachments)

and left domes

 Strenal  Costal

part (attaches to the xiphoid process)

part (attaches to the inferior six ribs)

 Lumbar

part (forms the and right and left crura, lateral attachments are through the medial and lateral arcuate ligaments)

DIAPHRAGM (continued)

Arteries - Pericardiophrenic and musculophrenic arteries (from the internal thoracic artery) - Superior phrenic arteries (branches of the thoracic aorta) - Inferior phrenic arteries (first branches of the abdominal aorta)

Veins - Follow the arteries of same name

DIAPHRAGM (continued)

Lymphatics - Drain into the parasternal, posterior mediastinal and phrenic lymph nodes

Nerves - Phrenic nerves (from the cervical plexus)

DIAPHRAGM (continued)

Diaphragmatic apertures Caval opening -

Transmits the IVC and right phrenic nerve

Esophageal hiatus -

Transmits the esophagus, anterior and posterior vagal trunks, esophageal branches of the left gastric vessels and some lymph vessels

Aortic hiatus - Transmits the aorta, thoracic duct, and the azygos and hemiazygos veins

POSTERIOR ABDOMINAL WALL (continued)

Fascia of the posterior abdominal wall - Lies between the parietal peritoneum and the muscles -

Continuous with the transversalis fascia laterally

Parts of the fascia of the posterior abdominal wall -

Psoas fascia (covers the psoas muscle) -

-

Quadratus lumborum fascia (covers quadratus lumborum muscle) -

-

Forms the medial arcuate ligaments on each side

Forms the lateral arcuate ligaments on each side

Thoracolumbar fascia (medially splits into two and encloses the deep back muscles -

Laterally attaches to the internal oblique and transverse abdominal muscles

POSTERIOR ABDOMINAL WALL (continued)

Lymphatics of the posterior abdominal wall  Common

iliac lymph nodes  Lumbar (aortic) lymph nodes  Preaortic lymph nodes (celiac, superior mesenteric and inferior mesenteric lymph nodes)  Efferent vessels from the preaortic lymph nodes form the intestinal lymphatic trunk and drain into the cisterna chyle (the begining of the

thoracic duct)