calcaneal tendon; his triceps surae
A heavyset middle-aged insurance salesman who doesn't exercise often accepts his friend's invitation to a pickup basketball game. When attempting a jump shot, he falls to the ground in pain, grasping at the calf of his leg. There is an enormous bulge in his leg immediately below the knee, and he is unable to plantarflex that foot. Most likely he has injured his ___ and the bulge is ___.