The Spinal Column
Because of complex interactions between the spinal column and the nervous system, disk injuries may cause arm and hand pain. The spinal column is composed of 33 bones known as vertebrae. Each vertebra is stacked on top of the other and divided into four regions, which include the sacrum and coccyx at the base of the spine, the lumbar region in the lower back, the thoracic region in the middle back and the cervical spine in the neck. The vertebrae has many important functions. It serves as a point of attachment for the muscles, ligaments and tendons. The spinal column is also responsible for multi-directional movement of the pelvis, trunk and neck. Movements originating from one point of the spinal column often affect movements or alignment in other parts of the spine.
Intevertebral Disks
The spinal vertebrae are separated by donut-shaped, fluid-filled disks, which serve as shock absorbers. The fluid inside the disk is called the nucleus pulposus, and the fibrous ring that surrounds the fluid is called the annulus fibrosus. The seven cervical disks enable flexion and extension movements of the neck. They can be injured in a number of ways. Chronic misalignment of the neck is one of the most common overuse injuries, but the disks can also be damaged by trauma. Age is also a factor. Over time, the nucleus pulposus may lose its elasticity, or the annulus fibrous may weaken and tear. A tear may cause the fluid to leak. If this happens, the fluid will put pressure on the nerve root or the spinal cord.
The Spinal Cord
The spinal column and disks are also responsible for the protection of the spinal cord, which is located behind the cervical disks. The spinal cord is the primary information pathway between the brain and the peripheral nervous system. The peripheral nervous system connects the central nervous system to the limbs of the body.
Cervical Nerve Roots
Cervical nerve roots are located on each side of the spinal cord. These roots contain sensory and motor fibers that travel to the neck, shoulders arms and hands. Disk damage may cause nerve root impingement, which will in turn send an impulse that travels out of the neck and through the brachial plexus. The brachial plexus is an arrangement of nerve fibers that begin in the neck and radiate to the arm and hand.
Pinched Nerves
The location of the pinched nerve will influence the site of the pain. For example, a pinched nerve in the sixth cervical vertebra or C6 may cause bicep and wrist extensors as well as pain and numbness that runs down the arm and radiates to the thumb. A pinched nerve at C7 will cause pain that radiates down the arm to the middle finger, and a pinched nerve at C8 can cause hand dysfunction.
