Motor function refers to the ability to move a joint in a particular direction.  A reduction or loss of motor function is simply the inability to move a particular joint in a particular direction, in comparison to the normal function of the joint.  (Loss of motor function is different than a reduction in the range of motion of a joint, which is usually limited by pain rather than an inability to move the joint at all.)

A full physical examination can reveal a reduction/loss of motor function.  The physician tests the patient’s ability to move each joint in every possible direction, usually by resisting the patient’s motion and determining how much resistance (if any) the patient can overcome.  The specific kind of examination depends on the joint and particular muscle being explored.  

Some varieties of loss of motor function have specific names, such as drop foot (the inability to dorsiflex the foot).

• Degenerated disc


• Vertebral fracture


• Spinal hematoma


• Hematoma