The two oblique grooves of the lateral surface of the calcaneus are separated by an elevated ridge, or tubercle, the trochlear process ( peroneal trochlea, or peroneal tubercle, or fibular trochlea of calcaneus), which varies much in size in different bones.

Its chief anatomical significance is as a point of divergence of the previously common pathway shared by the distal tendons of peroneus longus and peroneus brevis en route to their distinct respective attachment sites.

Reference:
The Lower Limb, Last's Regional and Applied Anatomy, 9th edition