Everything You Need to Know about C1 and C2 Vertebrae
While all spinal cord injuries (SCIs) can be dangerous and life-altering to the people who suffer them, there is one variety of spinal cord injury, in particular, that is considered the worst: an injury that falls within the cervical spinal cord — specifically at the C1 and C2 spinal cord injury level.
Injuries to the cervical spine at the C1 and C2 vertebrae make up just 2% of all spinal cord injuries. While they are considered the most severe of all spinal cord injuries, the effects of these injuries can vary depending on the completeness of the damage.
For identification purposes, the spinal cord is divided into multiple sections that correspond with the vertebral section of the spine in that area. Read on for more information on the fundamentals of these injuries, expected prognosis, and the latest treatments available.
What Are Vertebrae?
The spine is made up of 33 stacked bones called vertebrae. Medical professionals group these individual levels into five sections called:
The vertebrae of the spinal column are responsible for protecting the spinal cord, which is a bundle of nerves that relays messages between the brain and the rest of the body. Together, the spine and spinal cord are covered by a protective membrane, forming the spinal column. Spanning from the bottom of the skull to above the hips, the backbone supports all forms of movement — getting up, turning over in bed, standing, running, and crouching.
The first 24 vertebrae (working down from the skull) are distinct and mobile, but the remainder toward the bottom of the spine are fused and remain stable. Made of bone, and held in place with muscle and ligaments, the neck has the largest range of motion in comparison to other vertebrae.
What is a C1 Vertebra?
The seven vertebrae in the cervical region of the spine all work toward the same cause — moving the neck and holding the skull in place. On average, the human head can weigh between 10 and 13 pounds, yet the bones in the cervical spine are the smallest of all the spine's vertebrae. However, the very first two vertebrae, C1 and C2, have the most specialized jobs; allowing a unique set of movements for the skull.
The cervical vertebrae C1 is attached directly to the skull, which allows for any nodding lateral motions. The top foremost of the vertebrae, C1, allows for a greater range of motion than normal vertebrae.
What is a C2 Vertebra?
The C2 vertebra is the axis which the C1 vertebra pivots around and lets us move our skulls from side to side in a horizontal motion. Like the C1 vertebra, a C2 vertebra has a greater degree of motion than other vertebrae that are lower on the spinal column. Since the brain stem extends through the C1 and C2, it is extremely important to the neurological system.
C1 vs C2: Anatomy and Spinal Location
The cervical vertebrae known as C1 and C2 form the top of the spine (neck) at the base of the skull. These vertebrae are uniquely shaped and have vertebral foramen (spaces within the bone) which allow the vertebral arteries to reach through to the brain and supply it with blood. This vertebral formation is only seen in the cervical region.
C1 and C2 Vertebrae Names
The C1 vertebra is referred to as atlas—so named for the Greek myth in which the titan Atlas held up the sky. The second vertebra, C2, is called the axis in reference to its purpose — enabling motion. When together, atlas C1 and axis C2 allow for rotation and swiveling of the head since the C1 vertebrae is attached directly into the skull and pivots from its C2 axis.
How Many Cervical Vertebrae Are There?
The cervical spine is located at the very top of the spinal column. Besides the atlas C1 and axis C2 cervical vertebrae , there are five additional vertebral levels within this region (for a total of seven) which are classified as C1-C7 from the top down, forming the human neck. There is an additional cervical-level injury classification site known as a C8 injury which relates to damage to the spinal cord root that exits the spinal column between the C7 and T1 vertebrae.
What Are the Functions of the Cervical Spinal Cord?
The cervical spinal cord is the uppermost section of the nerves that are inside of the neck vertebrae. This region of the spinal cord, which is referred to by vertebral levels as C1-C7, is also the most sensitive in the sense that injuries at this level are the most life-threatening. The vertebrae in this region, atlas C1 and axis C2 , support your skull, allow you to turn and move your head, and protect your spinal cord.
To put it simply, higher the injury on the spinal cord, the more damage and loss of function the individual will experience. Since the cervical spinal cord is the highest part of the spinal column, SCIs in this section of the spinal column tend to have the gravest effects.
C1 and C2 Spinal Cord Injury Symptoms
Because the cervical spine is closer to the brain, and therefore affects a larger amount of the human body, spinal cord injuries that affect the atlas C1 and axis C2 sections of the spinal cord frequently result in death. For those who survive, these injuries often involve the loss of function to the neck and everything below it — which may result in full paralysis.
Other related effects include the loss of ability to:
- Clear saliva from the mouth;
- Speak clearly; and
- Control bladder and bowel functions.
When someone experiences complete or partial paralysis from the neck down — their trunk and all four limbs — it is commonly referred to as tetraplegia or quadriplegia. An injury to the cervical vertebrae C1 and a C2 spinal cord injury are both considered highly rare injuries to sustain. More common cervical spinal cord injuries affect the C4 and C5 levels of the spinal column.
Types of C1 and C2 Cervical Spinal Cord Injuries
Although injuries can occur at this level, they are not very common. Medical professionals see more injuries to the C4 and C5 area. The most frequent cause of a C1 fracture is diving, followed by vehicular accidents, and then falls that impact the head.
C1 and C2 Vertebrae Breaks, Fractures, and Misalignments
Atlas C1 and axis C2 injuries are the most severe because damage to the spinal cord at any level has potential to remove communication to the rest of the body below that point. Due to the high level and placing of these vertebrae at the top of the neck, having a C2 or C1 vertebrae out of place or suffering sustained damage is most often fatal (or leaves the individual fully paralyzed).
In addition to the initial vertebral injury, the interference at the C1 and/or C2 level can cause the vertebral arteries to inflict neurological damage; leaving the brain without a vital source of blood.
Symptoms following an injury to the cervical vertebrae C1 and C2 may include:
- Complete paralysis of arms and legs
- Muscle atrophy
- Limited head and neck movement
- Compromised continence control
- Trouble breathing without apparatus and assistance
- Ability to speak reduced or impaired
Treatment for C1 and C2
Immediate treatment is crucial in the case of a cervical vertebrae C1 or C2 injury, and the head must be securely stabilized to prevent any further damage. It is likely that the person may have suffered a concussion, and so may be unable to accurately report pain.
Keeping the head and neck in a constant position is one method of encouraging healing; one that is still in use today through various immobilization apparatuses, such as hard-collars or halo vests. Depending on the injury, an individual may have to wear these medical devices for a number of months. The halo vest has been used for many years. However, more recently, it has been shown to be effective at preventing any further neurological injury in people with cervical spine injuries.
Direct lateral mass screws are used to ensure no further movement of the vertebrae while preserving the upper cervical motion segments for the future. This surgical method has been extensively used, and studies have proven to be safe, with minimal complications and low rate of morbidity for cervical myelopathy treatment.
C1 and C2 Spinal Cord Injury Recovery
A person’s ability to heal and recover some function after a cervical spinal cord injury will vary from person to person depending on a variety of factors, including:
- Their health at the time of their injury (body type, existing medical conditions, etc.);
- How soon they received treatment and their injury was stabilized;
- The completeness of the injury;
- Whether anti-inflammatory and steroid medications were used after the injury to relieve swelling and pressure on the spinal cord;
- Whether the SCI survivor went through therapies and treatments at a rehabilitation facility that specializes in spinal cord injuries; and
- Whether the patient, their friends, family, or caregivers stick with a consistent care plan to aid their recovery.
People with these injuries also can get around with the help of power wheelchairs that are equipped with special assistive technologies that allow them to control the chair’s movement through unconventional means. However, they will require 24-hour care and assistance from family, friends, and/or a professional caregiver.
Incomplete vs Complete Injuries
Spinal cord injuries are considered either incomplete or complete, meaning that the communication between the spinal cord and the brain is either partially impeded or fully impeded. This could be due to tissue inflammation that is pressing against the spinal cord nerves, foreign objects, or partial or complete severance of the cord itself. This can result in the partial or full loss of motor and sensory functions below the injury site.
When someone experiences complete or partial paralysis from the neck down — their trunk and all four limbs — it is commonly referred to as tetraplegia or quadriplegia. An injury to the cervical vertebrae C1 and C2 spinal cord injury are both considered highly rare injuries to sustain. More common cervical spinal cord injuries affect the C4 and C5 levels.
- Complete injuries refer to instances in which a person retains no sensation or movement below the level of injury
- Incomplete injuries are not this finite. They may allow for some feeling, movement on one side of the body, or even movement in some limbs.
The American Spinal Injury Association (ASIA) devised a scale, the ASIA Impairment Scale, to classify injuries based upon a combination of criteria to assess whether an injury is complete or incomplete. Further information about completeness can be found by reviewing that scale.
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Spinal Cord Team