Chapter 125 discusses US examination of the calf, ankle, and foot, which is frequently performed to evaluate for muscle, tendon, and ligamentous injuries; joint effusions and synovitis; bursitis; plantar fasciitis; and Morton neuroma. US measurements of Achilles tendon ruptures in different ankle positions may help in guiding treatment selection. Dynamic US evaluation is the imaging study of choice to evaluate for peroneal tendon dislocation and intrasheath subluxation. The posterior tibial tendon (PTT) is the most commonly injured tendon at the medial aspect of the ankle which can be readily evaluated with US. US scanning may be comprehensive or focused to the region of interest.