In the original Latin, "cervix" means "neck." C4 is a term used to refer to the fourth cervical nerve, meaning the nerve that emerges from the spinal cord between the third and fourth vertebrae of the neck. The C4 nerve is part of the cervical plexus, a network composed of the first four cervical nerves. These nerves supply the skin of the neck and the back of the head as well as the diaphragm muscle. In certain circumstances, the C4 nerve can become pinched, and pain and dysfunction can result.
Intervertebral Disc Herniation
Cartilaginous discs serve as shock absorbers between the vertebrae of the cervical spine. Sometimes these discs can become damaged, and the spongy material at their core, known as the nucleus pulposus, can break through the outer ring, known as the annulus. This is known as a disc herniation.
Dr. Phillip S. Chua, chairman of cardiovascular surgery of the Cebu Cardiovascular Center in the Philippines, explains that the proximity of the nerves to these discs makes them vulnerable to impingement by cartilage that bulges out from the nucleus or annulus of the disc and into the areas that hold the nerves.
Osteophytes
Sometimes the C4 nerve is impinged not by cartilage from the intervertebral discs, but by bone from the vertebrae themselves. With advanced age, some degree of vertebral erosion is normal, due to the natural effects of wear and tear on these highly mobile units of bone. When bone tissue erodes, the body attempts to heal it by generating new bone cells around the affected area. This can lead to overgrowth of the bone tissue known as bone spurs, or osteophytes. The University of Maryland Medical Center explains that bone spurs cause symptoms identical to those of herniated discs.
Space-Taking Lesions
Though disc herniation and osteophytes are the most common causes of cervical nerve root impingement, any space-taking lesion within the neck can also be a source of cervical radiculopathy, or lesions of the cervical nerves. The "Journal of Orthopaedic & Sports Physical Therapy" lists a number of potential space-taking lesions that can impinge on cervical nerves, such as tumors and arterial inflammation.
Trauma
In some cases, injury can cause damage to the structures of the neck and lead to nerve root impingement. When the soft tissues are injured, the inflammation of the soft tissues can cause nerve compression and subsequent radiculopathy. The San José State University Kinesiology Department lists whiplash, torticollis, strain and stretching injuries among the potential causes of nerve root compression that are commonly experienced by athletes.
References
- CEBU Cardiovascular Center: Neck and Arm Pains
- University of Maryland Medical Center: A Patient's Guide to Cervical Radiculopathy
- San José University: Cervical Spine and Associated Injuries in Athletics
- "Journal of Orthopaedic & Sports Physical Therapy"; Diagnosis and Nonoperative Management of Cervical Radiculopathy; Maj. Robert S. Wainner, Ph.D., and Lt. Col. Howard Fill, M.D.; December 2000
