Forward bending of the back is known as flexion. Backward bending is known as extension. Back extensor muscles make this backward motion possible. In anatomical terms, they are known as the erector spinae or spinal erectors. They start at the base of the skull and run all the way down to the tailbone.

Pinched nerves are caused by excessive pressure being placed on a nerve by surrounding tissues. Pinched nerves can happen anywhere in the body, including the upper back, and they can cause pain, weakness and loss of mobility.

A rounded upper back, sometimes called a slouch, is correctly called hyperkyphosis. Hyperkyphosis can be caused by a number of factors including tight chest muscles, weak upper back muscles, an imbalanced exercise program with too much emphasis on pecs development or spending too much time sitting at a desk or driving.

Pull-ups and lat pulldowns share a number of similarities, including how the joints in the upper body move while doing them and the muscles they work. However, depending on your current strength levels, one exercise may be more ideal than the other.

Your back is made up of two major muscles. That includes the trapezius muscle, a large muscle that spans across the back of the neck and shoulders, down to the top of the lower latissimus dorsi muscle.

Strengthening and stretching the chest, core and back are necessary for proper posture. To lengthen the spine you must correct bad posture habits, such as slumping, slouching and swaying. To correct these habits you must be aware of how you sit, stand and walk, and strengthen and stretch the opposing muscles.

The midriff area is located below the chest and above the pelvis. When it comes to this area and the lower back, fat has a tendency to accumulate on both men and women over the years. These areas are no different than any other area when it comes to toning them.

There are two main types of curved spine: kyphosis and lordosis. From a side view, kyphosis is the excessive curvature of the thoracic spine, causing a "C" shape instead of an "S" shape of a normal spine.

Flexing your spine uses your rectus abdominus muscles at the front of your body and also stretches the erector spinea muscles of your back. Spinal flexion, in which you lean forward and round your back, can be active, such as when performing sit ups or crunches, or passive, as when leaning down to tie your shoe laces.

Located in your upper back and between your shoulder blades, the rhomboids are responsible for shoulder retraction, or the drawing of your shoulder blades together. If the rhomboids are weak or tight due to disuse, your shoulders will drift forward -- a common problem for people with sedentary lifestyles.

While you can't actually strengthen your spine, you can strengthen the muscles that surround it, and this thick group of muscles is called the erector spinea. They extend from the base of your head all the way down to the bottom of your back, and are essential for even the simplest of daily tasks.

Scoliosis affects about 2 percent of the United States population and is more common in young girls, although boys and adults may have scoliosis too, according to SpineUniverse.com. Approximately 80 percent of scoliosis cases are called "idiopathic" scoliosis, which means that the cause of the condition is unknown.