Blood Supply and Nerve Attachments

Blood Supply and Nerve Attachments

Generally, each muscle is served by one nerve, one artery, and one or more veins. Each of these struc-tures enters or exits near the center of the muscle. They then have multiple branches through the con-nective tissue sheaths (perimysium) of the muscle. While cardiac and smooth muscle cells can contract without any nerve stimulation, skeletal muscle fibers are controlled by nerve endings. A rich blood supply is found in skeletal muscle. This is because contract-ing muscle fibers require large amounts of energy. They need nearly continual delivery of oxygen and nutrients through their arteries. Large amounts of metabolic wastes are given off by muscle cells. These wastes must be removed through the veins in order for muscle contraction to continue to be effective. The smallest blood vessels in the body are the capil-laries of the muscles. They have many cross- links that allow for changes in muscle length. When a muscle stretches, the capillaries straighten, and when it con-tracts, they shorten. The majority of skeletal muscles spans joints and attach to structures, such as bones, in two or more places.