if(num_muscles<max_muscles-1&&attach1<num_joints&&attach1>=0&&attach2<num_joints&&attach2>=0&&attach1!=attach2){
muscles[num_muscles].parent1=&joints[attach1];
muscles[num_muscles].parent2=&joints[attach2];
if(num_muscles<max_muscles-1&&attach1<num_joints&&attach1>=0&&attach2<num_joints&&attach2>=0&&attach1!=attach2){
muscles[num_muscles].parent1=&joints[attach1];
muscles[num_muscles].parent2=&joints[attach2];