Anatomy, Structure and Function of the Spine and Related Injuries
Vertebral/Spinal Column
The vertebral column consists of 33 vertebrae separated by inter-vertebral discs. It serves to protect the spinal cord within the spinal canal.
| Type of Vertebrae | No. of Vertebrae |
| Cervical | 7 (C1-C7) |
| Thoracic | 12(T1-T12) |
| Lumbar | 5(L1-L5) |
| Sacral | 5(S1-S5) Fused |
| Coccygeal | 4 Fused – Tailbone |
Each vertebra is composed of a front segment (vertebral body) and a back segment (vertebral neural arch).
Functions of the Vertebral/Spinal Column
| Function | Description |
| Protection | Protects the spinal cord, which it encloses |
| Movement | Permits movement of the trunk: forward, backward, and left and right bending |
| Support | Supports the head |
| Production | Produces red blood cells |
| Attachment | Provides structural attachment for the ribs |
Inter-vertebral Disc
Discs are located between the vertebrae. Each disc has two function:
- It forms a fibro-cartilaginous joint which permits slight movement of the vertebrae
- and it works like a ligament by holding the vertebrae together.
The discs are composed of an outer part called the annulus, which surrounds the inner part, called the nucleus. The nucleus contains a gel substance with the consistency of jelly. It is the nucleus of the disc that acts as the body’s shock absorber between the vertebral bodies.
This jelly or nucleus may be forced out of the disc completely (herniated disc), causing pain as it exerts pressure on the nerve lying near the disc.
Functions of the Disc
- Resists compression and shearing stresses on the spine;
- Acts as a shock absorber;
- Separates Vertebrae.
Because the discs have little in the way of direct blood supply they rely on a supply of nutrients through the blood vessels and tissues. Without an adequate supply of nutrients the cells of the nucleus will die.
Injury to Discs
| Types of Disk | Characteristics |
| Normal Disc | A normal disk is perfectly formed and cushions the vertebrae above and below it. |
| Degenerative Disc | The natural degeneration of a disc through age. |
| Bulging Disc | Can occur when the disc moves out from its normal position |
| Herniated Disc | Can occur from a sudden injury sustained when lifting without bending the knees and keeping the back straight (i.e. bending at the waist) |
| Thinning Disc | Can be indicative of degenerative disc |
| Degenerating Disc | Can occur as a result the thinning of the discs it will result with the bones of vertebrae rubbing together |
| Osteophyte Formation | Can occur as a result of the friction of the two vertebrae rubbing together. It may encourage the growth of bone spurs (osteophytes) which can encroach on the nerves and cause severe pain. |
Back & Neck Pain
Posture
Learning and maintaining good posture is one of the best ways to prevent back and neck pain. Remember the spine is not naturally straight – it has natural curves both slightly forward in the lumbar region and backward in the thoracic region. The best posture to adopt is a neutral one. This can be achieved when the ears, shoulder and hips are aligned, whether you are sitting or standing.
Note: Holding your head in a forward posture can put additional and abnormal leverage on the cervical spine, thus pulling the entire spine out of its normal alignment. In addition forward head posture may cause reduced vital lung capacity due to loss of the cervical curve.
Back Pain
Back pain may occur as a consequence of:
- excessive wear and tear
- incorrect posture
- incorrect lifting techniques
- prolonged heavy physical work
- being overweight
- lack of fitness
- or underlying medical conditions.
Types of Back Pain
Mechanical Problems
- Herniated Disc
- Bulging disc
Cause
Weakness or tear in the outer ring of the disc: the nucleus moves outside and soaks up copious amounts of water. The nucleus then swells rapidly making it impossible for it to move back into the disc.
Effect
The herniated disc may exert pressure on the nerves resulting in pain, numbness, and a reduction of strength and ability to move.
Arthritis of Facet Joint
The facet joints are covered by smooth cartilage and surrounded by ligaments, and they are lubricated with a fluid called synovial fluid. The facet joints may develop arthritis and become painful.
Cause
The affected joints develop bone spurs ( a bony growth formed on normal bone). These bone spurs will restrict the space available for the nerve roots as they leave the spinal canal. Therefore the nerve roots become pinched causing pain, numbness and weakness.
Effect
Arthritis of the facet joints may cause back pain that worsens with twisting or bending backward movements.
Strained Muscles
Cause
Muscle fibres may become strained or abnormally stretched or torn as a consequence of overloading or sudden movement.
Internal Problems
Back pain may also be caused by presence of underlying medical condition.