Definition

The spine is a column of vertebrae in the back part of the upper body. It is also called the backbone or vertebral column. There is a canal that runs through the length of the spine. Inside this canal is the spinal cord. Animals that have a spine are called vertebrates, and animals that don’t have one are called invertebrates. Humans have a spine, so we are vertebrates. There are three natural curves in the spine that give it an “S” shape when viewed from the side. These curves help the spine with stand great amounts of stress by providing a more even distribution of body weight.

The spine is made up of a series of bones that are stacked like blocks on top of each other with cushions called discs in between to help absorb shock/load.

Functions

» Permits movement of the body, although limited movement between individual vertebrae.
» Encloses and protects the spinal cord.
» Provides points of attachment for the bones and muscles of the torso, especially muscles of the back.

Why There Are Curvres In Spine

Curves are structurally important shapes because they can be extremely efficient in terms of strength and load-carrying capacity (though, of course, the particular curve must be appropriate for its situation and the weight and other forces it must support or withstand).

In the case of the human vertebral column or spine, the curves that form the sections of a normal healthy adult spine enable the person to balance comfortably in an upright position. They also help the body to absorb jolts and other shocks from the usual motions expected in day-to-day life. For example, the shape (including the curves) of the human vertebral column helps to protect it from injuries such as fractures

Spine Categories

The spine is divided into three regions

» Cervical Spine – The cervical spine (or neck) is the uppermost part of the spine. There are seven vertebrae within the cervical spine, numbered C1 to C7 from top to bottom. The first two vertebrae of the cervical spine are specialized to allow for neck movement. C1 sits between the skull and the rest of the spine. C2 has a bony projection that fits within a hole in the atlas to allow rotation of the neck. The first spinal curve is located at the cervical spine. It bends slightly inward, resembling a “C.”

» Thoracic spine – There are 12 vertebrae (T1 to T12) in the chest section, called the thoracic spine. The ribs attach to the spine on the thoracic vertebrae. The curve of the thoracic spine bends outward like a backward S

» Lumbar spine – The lumbar spine (or lower back) usually consists of five vertebrae numbered L1 to L5. The lumbar spine, which connects the thoracic spine and the pelvis, bears the bulk of the body’s weight and are the largest vertebrae. The curve of the lumbar spine also bends inward (lord tic curve).

What Is Sacrum

Below the lumbar spine is a large bone called the sacrum? This bone is shaped like a triangle that fits between the two halves of the pelvis, connecting the spine to the lower half of the body.

The sacrum actually consists of several vertebrae that fuse together during a baby’s development in the womb. The sacrum forms the base of the spine and the back of the pelvis.

The spine is sometimes discussed by parts: bones (and joints) and soft tissues.

Vertebrae (Bone) / Joints

Vertebrae are the 33 individual bones that interlock with each other to form the spinal column, the upper twenty-four are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx or tailbone (which is another specialized bone created by the fusion of several smaller bones during development and it is below sacrum).

» Body – The body is the front portion and the main weight-bearing structure of the vertebra.
» Spinous process – The spinous process is the posterior, or rear, portion of the vertebra. It is the bony ridge you can feel down your back.
» Laminae – These are two small plates of bone that join in the back of the vertebra.
» Pedicles – Pedicles are short, thick bumps that project backward from the upper part of the vertebral body.
» Transverse processes – These are the bony projections on either side of the vertebra where the lamiae join the pedicles. Muscles and ligaments attach to the spine on the transverse processes.
» Facet joints – These are the spinal joints, the areas on the spine where one vertebra comes into contact with another.

In the center of each vertebra is a large opening, called the spinal canal, through which the spinal cord and nerves pass. The vertebrae are held together by groups of ligaments, fibrous tissues that connect bone to bone.

Intervertebral Discs

Intervertebral discs are flat, round cushioning pads that sit between the vertebrae (inter means “between” or “within”) and act as shock absorbers. Each intervertebral disc is made of very strong tissue, with a soft, gel-like center — called the nucleus pulpous — surrounded by a tough outer layer called the annulus. When a disc breaks or herniates (bulges), some of the soft nucleus pulpous seeps out through a tear in the annulus. This can result in pain when the nucleus pulpous puts pressure on nerves.

Nerves

The spinal cord, the column of nerve fibers responsible for sending and receiving messages from the brain, runs through the spinal canal. It is through the spinal cord and its branching nerves that the brain influences the rest of the body, controlling movement and organ function.

Soft Tissues

Tendons connect muscles to bone and assist in concentrating the pull of muscle on bones. Ligaments link bones together, adding strength to joints. They also limit movements in certain directions. Muscles provide movements of the body and help maintain position of the body against forces such as gravity.

How Spine Is Damaged

» Infections
» Injuries
» Tumors
» Bone changes that come with age, such as spinal stenosis and herniated disks

Spinal diseases often cause pain when bone changes put pressure on the spinal cord or nerves. They can also limit movement.

As you grow older, the years of tension and stress that your spine endures can take a toll on the intervertebral discs and ultimately lead to degenerative spine disorders. Age-related changes can also cause the discs to become drier and weaker, making them more prone to damage.

Common types of degenerative spine diseases

» Spinal osteoarthritis. Also referred to as degenerative spinal arthritis, this condition involves the breakdown of cartilage located on the spinal facet joints. When osteoarthritis occurs, cartilage wears away, allowing bone-on-bone contact to occur within the joint. This can cause inflammation, the formation of bone spurs and nerve irritation.

» Degenerative disc disease. This condition describes the breakdown of intervertebral discs. When we grow older, the intervertebral discs dehydrate and the proteins that keep them healthy break down. As the discs deteriorate, they become less effective at supporting the vertebrae. This can cause the vertebrae to become slightly displaced and put pressure on the nerve roots that travel in between the vertebrae, or press on the spinal cord itself.

» Bulging discs. A bulging disc refers to an intervertebral disc that has sssswelled beyond its normal parameters between adjacent vertebral bodies. The enlarged disc remains structurally intact but due to increased pressure, has expanded into the spinal column. A bulging disc is not inherently symptomatic, but when the disc wall comes in contact with the spinal cord or any nearby nerve infrastructure, painful symptoms can develop.

» Herniated discs. A herniated disc refers to an intervertebral disc that has ruptured, allowing the inner gel-like disc material to seep into the spinal canal through a tear in the disc wall. This condition can be painful if the nerves that innervate the disc become irritated as a result of the rupture or if the extruded disc material irritates the spinal nerves. Herniated discs might develop as a result of an injury, but can also be caused by disc weakening that comes with age.

» Spondylolisthesis. Spondylolisthesis is a condition indicated by the presence of vertebral misalignment. In an otherwise healthy spine, the spinal column has a natural “S”-curve that evenly distributes weight along its length. With spondylolisthesis, one of the vertebral bodies in the spinal column slides out of its normal position. This condition is described in degrees of severity, with Grade 1 spondylolisthesis representing 0 to 25 percent slippage and Grade 4 spondylolisthesis indicating 75 to 100 percent vertebral slippage.

» Degenerative scoliosis. While most people equate scoliosis with adolescence, degenerative scoliosis is a spine condition that can develop later in life. When scoliosis occurs, it causes a side-to-side curvature of the spine, which can result in symptoms including a hunched posture or a change in gait.

» Bone spurs. Bone spurs are smooth protrusions of excess bone that frequently accompany arthritic deterioration. While these growths of bone are asymptomatic in and of themselves, the excess material can become problematic if it comes in contact with a nearby nerve. Bone spurs also often form in the aftermath of an injury.

» Spinal stenosis. Spinal stenosis describes the narrowing of the spinal canal. This isn’t necessarily problematic by itself, but when the canal space becomes constricted, the spinal cord and other nerve structures can be irritated. Common causes of spinal stenosis include the presence of herniated disc material, bone spurs and other tissue.

» Foraminal stenosis. Foraminal stenosis describes the narrowing of the passageways through which nerve roots enter and exit the spinal canal. Like spinal stenosis, this condition isn’t symptomatic by itself, but if the space becomes so narrowed that the nerves are irritated, a variety of painful symptoms may develop. Often, this condition causes discomfort to travel the length of the affected nerve, potentially causing pain to develop in areas seemingly unrelated to the spine.

» Pinched nerves. A pinched spinal nerve is a common condition that most people will experience on occasion, as they grow older. When the symptoms of a pinched nerve don’t go away on their own over several days, they could be the byproduct of one of the aforementioned degenerative spine conditions. Alleviating the symptoms is contingent on identifying and addressing the cause of the nerve constriction.

» Sciatica. Sciatica is a term that is frequently used as a catchall to describe the symptoms that arise from the inflammation and irritation of the sciatic nerve. This nerve originates at the base of the spinal cord and extends downward through the lower body before ending near the feet. Most commonly, sciatica is associated with chronic lower back and leg pain.