In between the vertebrae of the spine are round, flat discs that function as cushions. These discs absorb shock as well as the stress of body weight and they ensure the spine maintains its flexibility. Should they deteriorate or if the stress becomes too much, they may begin to swell or they may even rupture, causing the gel inside of the disc to leak potentially irritating spinal nerves. These herniated discs can occur anywhere in the spine but tend to occur most commonly in the neck and lower back. Being unable to lift the foot up is a symptom as well as pain, weakness, or numbness in the neck, shoulders, or limbs.