The spinal column is the center for control of our posture and provides our stability when we stand. It also allows for flexibility, so that we can do different things such as stand or sit, stretch backward or bend forward. We can even twist our backs or necks one way or another. Because of its many functions, the spine is very vulnerable to injury¡ª injuries can occur to the bones themselves, the ligaments that connect the bones, discs that separate each vertebral bone from one another, or muscles that give movement to our spinal skeleton.

The human skeleton

The skeleton is the part of the body that consists of both the rigid and semi-rigid structures that support the soft tissues, such as the muscles, in our bodies (Figure 2). Tough fibrous bands called ligaments connect the bones and joints of our skeletons. Finally, the bones are connected to muscles by tendons. The muscles are controlled voluntarily by our nervous system and they give purposeful motion to our skeleton

Figure 2: Human Skeleton

The spine

The spinal column (also called the vertebral column) consists of

• 7 cervical (neck) vertebrae,
• 12 thoracic (chest) vertebrae,
• 5 lumbar (back) vertebrae, and
• 5 fused vertebra that make up the sacrum and coccyx, the very bottom of our vertebral column.

Figure 3: The Vertebral Column

See Figure 3. The vertebral column has four curves in it. The anterior sacral convex curve curves toward the belly or pelvic region. The lumbar lordosis curves toward the back. The thoracic kyphosis curves toward the front of the chest, and the cervical lordosis curves toward the back of the neck. Figure 4 shows a drawing of a motion segment of the spine.

Figure 4: A) A view of a lumbar vertebra looking from the back to the front of the spine (that is anterior to posterior). B) A view of a lumbar vertebra looking from side to side.

Ligaments

The ligaments of the spine are fibrous tissues that keep the bones and joints in alignment (Figure 5). Under stress ¡ª for example if you are injured ¡ª these ligaments can stretch or break, causing pain. A partial or complete tear of a ligament is called a sprain.

Figure 5: The bones of the spine are connected by many fibrous ligaments. These ligaments can stretch or tear, causing back pain.

Discs

Discs are located between the vertebrae and act as the shock absorbers of the spine. The discs are made up of fibrous layers ¡ª called the annulus ¡ª surrounding a gel-like substance called the nucleus pulposus or nucleus (Figures 6 and 7).

Figure 6: Discs