Deep (autochthonous) back musculature

by Denise Müller, Grad. Sports Scientist

Back musculature means the skeletal muscles in the back area (dorsum). From an evolutionary standpoint, we can distinguish between two types of muscles. Firstly, the muscles located directly along the spinal column, and secondly muscle groups that have branched out in a secondary system across the back. The autochthonous musculature is therefore also referred to as eutopic (locally resident), primary, or genuine back musculature, which is subdivided in a medial (centrally located) and lateral tract. These are found to the left and right of the spinal column, reaching from the hip along the ribcage right up to the head. The medial tract is located between the spinal process and transverse processes of the vertebrae. The lateral tract consists of a system of long muscles. It is closer to the surface than the medial tract, and acts more laterally. That is why this muscle group is referred to as the “straightener” or “stabiliser” of the spinal column, in medical terms it is referred to as “musculus erector spinae”. The autochthonous back musculature differs from all other skeletal muscles in the human body as it is innervated by the branches of the spinal nerves - the rami posteriores and dorsales. Another key difference that sets other autochthonous muscles (e.g. the costal muscles between the ribs, and the abdominal muscles) apart from the autochthonous back musculature is the fact that they are enclosed in the fascia thoracolumbalis from the hip to the chest. The fascia forms a capsule affixed to the spinal column, which encloses the various muscle parts. In the neck area, the fascia nuchae replicates that same capsular form. The autochthonous back musculature is essential for the stabilization and movement of the spine. Bilateral contractions result in a stretching of the body (dorsal extension). Unilateral contractions would result in a stretching to the side (lateral flexion). A rotary movement of the upper body can only be achieved in conjunction with the oblique abdominal muscles. The deep neck muscles support movement in the head joint, and most importantly assist fine motion adjustment. They have an extraordinary number of muscle spindles and are therefore critical for deep sensibility.