1 Chemically, ATP is an adenine nucleotide bound to three phosphates. 2  There is a lot of energy stored in the bond between the second and third phosphate groups that can be used to fuel chemical reactions. 3  When a cell needs energy, it breaks this bond to form adenosine diphosphate (ADP) and a free phosphate molecule.
calf muscle pump. calf muscle pump. an action of the calf (soleus) muscles in which the muscles contract and squeeze the popliteal and tibial veins, forcing the blood in those veins to move upward toward the heart. Also called soleus pump.
Motor Functions. The musculocutaneous nerve innervates the muscles in the anterior compartment of the arm â the biceps brachii, brachialis and coracobrachialis. These muscles flex the upper arm at the shoulder and the elbow. In addition, the biceps brachii also performs supination of the forearm.