- O: lateral condyle & proximal ½of lateral aspect shaft of tibia,interosseous membrane
- I: medial & inferior aspect of medial cuneiform, base of 1stmetatarsal
- N: deep peroneal n. L4,L5
- A: inverts and dorsiflexes foot
*Reversed O-I action: When standing, the foot is fixed and becomes the origin. Action causes forward body lean antagonistic to the plantar flexion of the soleus and gastrocnemius. Active in the balance mechanism of anterior and posterior sway.