Acting via the<unk> , the gastrocnemius and soleus muscles cause plantar flexion of the foot at the ankle. This action brings the sole of the foot closer to the back of the leg. The gastrocnemius also flexes the leg at the knee. Both muscles are innervated by the tibial nerve. Because the fibres of the<unk>  spiral about 90 degrees, fibres from the gastrocnemius tend to attach to the outer part of the bone, whereas fibres from the soleus tend to attach closer to the midline. Vibration of the<unk>  without vision has a major impact on postural orientation. Vibration of the<unk>  causes movement backwards and the illusion of a forward body tilt in standing subjects. This is because vibrations stimulate muscle spindles in the calf muscles. The muscle spindles alert the brain that the body is moving forward, so the central nervous system compensates by moving the body backwards.
Achilles tendon
Deltoid muscle
Nerve fascicle
Mesna
Axon hillock
Pivot joint
Pectus
Ulnar claw