The vastis medialis oblique—VMO for short, because vastis medialis oblique is a mouthful.
The VMO is the most bottom portion of the vastis medialis, which is on the most inner of the quadriceps muscle, just above the kneecap. The quadriceps are in the front of the thigh.
The VMO is responsible for the full extension of the knee which is essential for walking. Inflammation, acute or chronic, will cause the VMO to not contract properly.
An improperly activating VMO will cause the kneecap to not move in the correct path during knee bending which can lead to knee dysfunction and pain.
VMO strengthening can be challenging. Ask Mike, Chip, or Sharon if you want to know how to strengthen your VMO.