Spine (Back and Neck) Injuries and Conditions

Spine anatomy

The spine, or backbone, is the center of support for the upper body. This column of bones and cartilage extends from the base of our skull to the pelvis, enclosing and protecting the spinal cord. Ligaments and tendons and large muscles connect to the spine, while highly sensitive nerves extend outward from the spinal cord. The spinal cord extends from the base of the brain and enters the spinal canal, a protective space within our bony spine, to carry signals to and from the brain throughout the body.

A healthy spine is both highly flexible and very strong. Its strength holds up our head and shoulders and supports our upper body. It allows us to stand up straight. The flexibility of the spine enables us to bend and twist.

Vertebrae

The spine is not one long rigid bone. It consists of 24 small bones called vertebrae that are stacked in a column from the pelvis to the base of our skull. These bones connect to create a canal that protects the spinal cord.

The vertebrae are divided into four regions. From top to bottom, these are:

The curves of the spine

The spine is not perfectly straight; it has natural curves. If you were looking at the spine from the side, you would see that it is curved like an elongated 'S'. These natural curves are very important. When properly maintained, they give the spine full mobility and provide stability for the backbone and surrounding trunk. Good posture is important to maintain the health of our spine.

Spinal cord and nerves

The spinal cord is a cylinder of nerve tissue. Roughly the thickness of a finger, it extends from the skull to the lower back, traveling through the middle part of each stacked vertebra, called the central canal. Nerves branch out from the spinal cord through openings in the vertebrae and carry messages between the brain and the muscles.

Spinal discs

Structures called intervertebral discs are located between each vertebrae. They are flat and round, and about half an inch thick. Their main purpose is to provide shock absorption and allow mobility between the vertebrae. The structure of a spinal disc can be likened to that of a jelly doughnut. It has an outer ring of firm, spongy, malleable material and an inner core composed of a jelly-like substance.

A herniated disc is a common condition that affects these soft tissues. A disc herniation (sometimes called a "slipped disc") occurs when a portion of a disc's inner core bulges or ruptures through the outer ring, putting pressure on a spinal nerve. This may cause low back pain and/or leg pain – such as that associated with sciatica – leg weakness, leg numbness, cauda equina syndrome and other problems.

Illustrations of the axial (overhead) view of a healthy disc and a herniated disc putting pressure on a spinal nerve.

Spinal musculature

The spine is supported and controlled by several layers of muscles that perform different actions, yet work together in a harmonious fashion to support the spine, hold the body upright and allow the trunk to move, twist and bend.

Long and thick muscles span much of the back and function like guide wires, protecting the spine from excessive and sudden movement.

Deep and thinner muscles connect from the rib cage to the pelvis and hips. Together, these muscle groups act as a natural corset to provide stability and a foundation from which the hips and pelvis can derive power. This is known as core musculature.

Spine animations library

Watch videos that illustrate and explain various spinal conditions and injuries, including surgical treatments. (Each surgical animation provides only a general overview of a particular orthopedic procedure. HSS surgeons tailor each operation to the individual patient.)