You will find the muscle spindles here attached to two different points along the perimysial sheath. The spindle is subjected to an average of the activity of all the muscles fibers operating within the enclosed fascicle. A single lymph ductule attaches to the spindle sac. These bypass ducts have thicker muscle walls at the arteriolar end than the arterioles they branch off of, and serve two purposes. When you are asleep and at your basal metabolic level, so few capillaries are open that they would not pass enough blood to maintain the minimum venous return volume needed to keep the heart from losing its prime as a pump.
More blood passes through the bypass shunts to maintain that critical volume.
This action is partly due to the muscle venous pumping system being inactive at basal level. The shunts also allow blood to remain in motion so that as the capillaries open and close, the blood needs only be diverted and not accelerated or braked to a stop. The only structures that penetrate the perimysial fascia to run through the corridors provided by adjacent endomysial fascia are motor nerve fibers and capillary beds. The motor nerves then penetrate the endomysial fascia to form an end plate on the enclosed muscle fiber. Remember that the alpha motor nerve is called the final common pathway indicating that there are numerous synapses on the dendrites of the cell body in the spinal cord.