Functions:
Calf helps to support the knee joint and ankle joint and helps in leg movements. It is helpful in walking, running, jumping etc.
Diseases:
Calf pain or swelling is common in some conditions like varicose veins, tendon tear, deep vein thrombosis etc.
Interesting Facts:
Humans have exceptionally large calf muscles due to our upward stance, which requires the entire body weight to be supported on two limbs instead of four like most of animals.