knee
The flex
Flexor
A flexor muscle.
The flexor is a muscle that bends part of your body.
neck
The crystalline lens is the part of the eye that bends/refracts the light rays as it passes through it.
Spine. Bone, not muscle.
Delta is a body part and also a name for a landform where a river flows into an ocean or a larger body of water.
The knee is a body part that has "ee" in its name.
The Bends
eyes
The cornea is the part of the human eye that bends light rays the most when focused on a distant object.