Cardiac muscle the walls of a house contain electrical wires and plumbing, cardiac muscle also contains specialised cells for conducting electrical signals rapidly (the cardiac conduction system), and blood vessels to bring nutrients to the muscle cells and take away waste products (the coronary arteries, veins and capillary network). Cardiac muscle cells or cardiomyocytes are the contracting cells which allow the heart to pump. Each cardiomyocyte needs to contract in coordination with its neighbouring cells to efficiently pump blood from the heart, and if this coordination breaks down then – despite individual cells contracting – the heart may not pump at all,
Lumbar veins Lumbar veins The lumbar veins are veins running along the inside of the posterior abdominal wall. They are the lumbar equivalent of the posterior intercostal veins. They are four in number and accompany the four lumbar arteries, with the vein lying superior to the artery (the same arrangement as in the intercostal neurovascular bundles). The first and second lumbar veins usually join the ascending lumbar vein rather than the inferior vena cava, which then joins the subcostal vein of the same side to form the azygous vein on the right or hemiazygous vein on the left. The third and fourth