The vacuole i believe is the answer
The triceps brachii muscle is the large muscle on the back of the upper limb of many vertebrates. It is the muscle principally responsible for extension of the elbow joint.
blood flows at a high pressure, so if the arteries are thin and less muscular, the arteries can explode due to the pressure. so it needs thick and muscular properties so that it can withstand the increasing pressure of the flow of blood.
im not sure why it needs to be elastic. Hope it helped :)
<em><u>ANSWER:</u></em><em><u> </u></em>
<em><u>The </u></em><em><u>ans </u></em><em><u>is </u></em><em><u>true!</u></em>