Understand and Visualizing Atlas Transverse Contact

The NUCCA procedure for doctors is predicated on the precise and scientific analysis of the cervical spine and skull and how it influences the balance and health of the body. This scientific understanding is critical for the doctor to properly correct the Atlas Vertebral Subluxation Complex (ASC). NUCCA continually teaches doctors to understand the sophisticated biomechanics involved in the cervical spine.

This article is written for the purpose of properly understanding and visualizing the surrounding anatomy of the atlas vertebral transverse process (Atlas TP). This information is necessary if the doctor is to properly contact and correct the ASC. Article s have been written that teach the use of artifacts on the earlobe to stand out on x-ray to help the doctor in contacting the atlas TP. It is this writer's belief that the doctor first needs a precise understanding of the related anatomy for proper visualization. Any use of artifacts on the x-ray film cannot replace correct knowledge of this region of the spine. Distortion of anatomical structures on x-ray is given as the reason for relying on artifacts, but it is my belief that distortion is not as great a problem as it is conjectured to be. It appears that when one relies on the use of artifacts for location of atlas TP, the practitioner will not properly visualize the surrounding area. I feel the doctor needs to be familiar with the surrounding anatomy to be able to apply the proper contact for the atlas TP.

The proper procedure for identification of the atlas TP is to relate all three radiographs used for analysis of the ASC. Each radiograph is important for correct structure identification. The doctor needs to stand back and look at the radiographs and visu alize how the atlas structurally relates to the occiput bone, temporal bone, mandible and axis vertebra.

The doctor should first identify structures on the Nasium radiograph, in order to identify the structures on the Lateral radiograph. The structures to be properly identified are the inferior mastoid process, occipital condyles and atlas TP on the side of laterality. These structures must be properly related to each other for correct relationship on the lateral film. The inferior mastoid process is visualized in relation to the inferior occipital condyles. It is important to note whether the inferior masto id is superior, at the same level or inferior to the occipital condyles. This information is then taken to the lateral film for proper location of the mastoid process.

The lateral radiograph is next analyzed for structure identification. Doctors should be well acquainted with the anatomical architecture of the temporal bone(1), how it forms the mastoid process, how it helps form the external auditor y meatus and the mandibular fossa for proper articulation of the mandible bone (fig. 1). It is important to know how C-1 articulates with the occipital condyles and how the atlas TP is anatomically located in relation to the mastoid process, the external auditory meatus, the mandible, the occipital condyles and the lateral mass of the atlas. This knowledge of the related structures is most important if one is to properly correct the ASC.

To secure the correct location of the atlas TP, measurements are first made on the Nasium radiograph on the side of atlas laterality. A horizontal line (line A) is drawn across the film connecting the inferior apexes of the mastoid processes of the skull. A line (line B) is also drawn horizontally across the film connecting the inferior medial apexes of the occipital condyles of the skull. Another horizontal line (line C) is also drawn across the film on the superior atlas transverse process tubercle on the side of laterality. Two measurements are made at this time; the first between line A and line B for the distance between the mastoid process and the occipital condyle on the side of atlas laterality. The second measurement is made between line B and l ine C for the distance between the occipital condyle and the superior atlas transverse process on the side of atlas laterality. In the majority of cases the superior border of the transverse tubercle is on the same plane as the inferior occipital condyles . This measurement is then transferred to the Lateral film for the correct distance and relationship between the mastoid process, occipital condyle and atlas transverse process. I believe distortion is minimal on the Nasium film because of the close proxi mity of the structures to the x-ray film. Accurate measurements can be made on this film. See fig. 2.

On the Lateral film it is important to draw the outline of the mastoid process, its anterior-superior border and outline its formation of the external auditory meatus. This is important for correct measurement and relationship of its location to the atlas TP. Structures are larger on the Lateral film due to their greater distance from the x-ray film thus creating increased distortion. Correct measurements can be taken from the Nasium film, but must be adapted from the Vertex film. See fig. 3.

Continuing on the Lateral film, once the mastoid process and external auditory meatus have been outlined, outline the occipital condyle. The distance between the occipital condyle and the mastoid process is the measurement between line A and line B. The distance between the occipital condyle and the atlas TP is the distance between lines B and C. The atlas TP is most often found in the center of the lateral mass of the atlas on the lateral film and at the level of the occipital condyle. To correctly find its A-P location, measure on the Vertex film its distance posterior to the atlas anterior tubercle. On the Vertex film structures are close to the film where the distortion is minimal. Berti(2) noted on the Vertex film the atlas vert ebra is four and one-half inches from the film and on the lateral film it is eight and one-half inches from the film, causing three-sixteenths of an inch of distortion in the A-P length of the atlas vertebra. This correction is subtracted in our calculati on. On the Vertex film draw a horizontal line at the anterior border of the anterior atlas tubercle (line D) and horizontal lines at the anterior border of the atlas TP (line E) and the posterior border of the atlas TP (line F). See fig. 4. Measure the distance between lines D and E for the distance of the atlas TP from the anterior tubercle. Transfer this measurement to the Lateral film for correct distance of the atlas TP from the anterior tubercle. Subtract three-sixteenths of an inch for distortion. Also measure the A-P distance of the atlas TP on the Vertex film (line E and F) for correct A-P distance of the transverse tubercle. The superior-inferior size of the atlas TP can be measured from the Nasium film.

These measurements will help the doctor to more accurately measure the correct location of the atlas TP for proper contact. The doctor should take his/her time in these measurements and reason that these measurements make sense. Knowledge of the anatomic al structures are the basis of the specific and correct adjustments.

References:
1. Grays's Anatomy, 35th British edition, Philadelphia, W.B. Sanders Co., 1973.

2. Berti, A. "Identifying and Locating the Transverse Process of C1," Upper Cerv. Mono. Aug., 1990 4(10) 1-2.