METHODS: Seventy-five cadavers (27 females and 48 males) were surveyed. When the rectus capitis posterior minor was revealed, its superior attachment was detached and the muscle was reflected inferiorly to determine if it was attached to the underlying posterior atlanto-occipital membrane. If a soft-tissue bridge was identified, the fibers found within the bridge were classified by visual inspection into three categories: tendon-like, muscle-like, and fascia-like. A fourth category, no attachment, was also noted.
RESULTS: The rectus capitis posterior minor was present bilaterally in 93% of all cadavers surveyed (89% of the female cadavers and 96% of the male cadavers). On the right side, a soft- tissue bridge was present 67% in males and 78% in females. On the left side, the soft-tissue bridge was present 69% in males and 82% in females. The number of male cadavers possessing tendon fibers in a soft-tissue bridge was 56% on the right side and 55% on the left side. In females, the number of cadavers possessing tendon fibers in a soft-tissue bridge was 44% on the right side and 64% on the left side. In males, muscle fibers were present in the soft-tissue bridge 34% on the right side and 36% on the left. In females, muscle fibers were found in the soft-tissue bridge 43% on the right and 36% on the left.
DISCUSSION: There were no significant associations of sex and the presence of the soft-tissue bridge and a fiber-type within a soft-tissue bridge. This project provided evidence for a soft-tissue connection between the posterior atlanto-occipital membrane and rectus capitis posterior minor being present more often than absent and reflective of normal anatomy. These results provide the doctor of chiropractic a strong anatomical basis for headaches caused by soft-tissue spasm and cervical joint dysfunction at the attachment sites for the rectus capitus posterior minor.
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