Deep Back Muscles Beneath the Skin, Posterior View

Description

Visible beneath the reflected skin of the posterior trunk, the transversospinalis group occupies the groove immediately adjacent to the spinous processes from the upper thoracic region into the cervical spine, with semispinalis capitis forming a paired column that runs superiorly and slightly laterally to insert between the superior and inferior nuchal lines of the occipital bone. Deep to the trapezius and latissimus dorsi, the erector spinae (iliocostalis, longissimus, spinalis) lies lateral to the spinous processes and superficial to the deeper short rotators, creating a clear medial to lateral layering from multifidus and rotatores toward the costal angles. Cervical fibers approach the midline under the splenius region, while thoracolumbar fibers broaden inferiorly over the posterior elements of the vertebrae. Short segmental architecture dominates. Semispinalis and multifidus matter because they are primary stabilizers of the vertebral column during extension and controlled rotation, and their segmental attachments explain why focal injury can produce pain that feels diffuse. In lumbar spine surgery, splitting the multifidus from the spinous process or detaching it from the mamillary processes risks postoperative atrophy and persistent axial back pain, so surgeons increasingly plan muscle-sparing posterior approaches with these layers in mind. This posterior dissection also supports teaching of medial branch blocks and radiofrequency ablation for facet-mediated pain, where the target nerves course at predictable depths relative to multifidus and the zygapophysial joints. Ideal for gross anatomy lab guides, spine biomechanics lectures, and neurosurgery or orthopaedic texts that need a clean posterior reference for deep paraspinal layers. Pain medicine and physical therapy materials can also pair this plate with palpation landmarks and segmental stabilization concepts. Anatomical accuracy verified by SciePro's Medical Advisory Board.