An alternative didactic, functional and topographic systematization of the spinal muscles.

Back muscles are commonly described in a topographically-oriented manner without necessarily following morphological criteria. In this manner, non-standard terms may be employed which convey incorrect morphological concepts and demanding more time from both faculty and students to transmit knowledge. We propose a classification system for spinal muscles incorporating morphological concepts with the goal of facilitating knowledge transfer and suggest the term "spinal muscles". Those muscles were systematically divided and classified in seven strata from anterior to posterior: vertebro-appendicular (VA), transversarium (Tr), deep post-transversarium (DPT), middle post-transversarium (MPT), superficial post-transversarium (SPT), deep spino-appendicular (DSA) and superficial spino-appendicular (SSA). Besides topography and function, this system incorporates innervation and embryological origins of each muscle. The extrinsic (VA, DSA, SSA) or intrinsic (Tr, DPT, MPT, SPT) nature of these muscles in relation to the spine and also the topographic relationship to the transverse process is represented in this system. Specific areas of functional, nervous and developmental transition exist on Tr and DPT strata due to being adjacent to extrinsic strata. We believe this system represents a more modern and concise teaching strategy for back muscles which may be employed partially or fully within any program. We envision its full version may be particularly useful in postgraduate medical training for specialties dealing with the spinal column such as neurosurgery, orthopedic surgery and physical medicine and rehabilitation.