The fibula:
(a) Forms an important part of the knee joint
(b) Articulates with the femur
(c) Helps to bear the weight of the body
(d) Provides lateral stability to the ankle
(e) Does a and b
It is important because structures (anatomy) can change rapidly depending on the function (physiology) that must be performed.
It is important because how something functions (physiology) is directly dependent on its structure (anatomy).
It is important because understanding how something works (physiology) is more relevant to curing disease.
It is important because physiology exists to develop the correct anatomy.