Sensory nerve formations in the myodural bridge complex of adult humans

The myodural bridge complex (MDBC) consists of connective tissue bands connecting the spinal dura mater to the suboccipital muscles passing throughout the posterior atlanto-occipital and atlanto-axial spaces. It is a universal evolutionarily conserved anatomical structure present in most vertebrate species including humans. Its physiology is unknown, but it is thought that it may be related to cerebrospinal fluid circulation. On the other hand, there is no information about the possible innervation of MDBC in humans. In the present study, immunohistochemistry (S100 protein and neurofilament proteins) was used to study the innervation of MDBC in five specimens of adult human cadavers. In all cases, nerve profiles were observed forming isolated nerve fibers or small nerve bundles, sometimes associated with blood vessels. In one case (1/5), at the level of the junction of the MDBC with the posterior rectus capitis minor muscle, complex capsulated formations containing a variable number of sensory nerve formations were found. We consider that such formations may be related to the proprioceptor system of the suboccipital muscles, but further studies are needed to determine their frequency, density and possible function.