Longissimus Thoracis Muscle

Description

Running longitudinally along the posterior thoracolumbar spine, the longissimus thoracis forms the intermediate column of the erector spinae, positioned lateral to spinalis and medial to iliocostalis. Its muscle belly and segmental fascicles lie deep to trapezius and latissimus dorsi, with attachments spanning the lumbar transverse processes and thoracolumbar fascia inferiorly toward the thoracic transverse processes and adjacent ribs superiorly. In this posterior view of a female figure, the paraspinal mass creates a paired ridge on either side of the spinous processes, continuing inferiorly toward the sacral region and blending with the posterior abdominal wall aponeuroses. Clear layering. Longissimus thoracis is a primary extensor and ipsilateral lateral flexor of the thoracic and lumbar vertebral column, so its orientation and depth matter when teaching how the erector spinae stabilize the spine during gait and lifting. Clinically, this muscle is commonly involved in paraspinal strain and myofascial pain patterns that refer along the thoracolumbar junction, and its hypertrophy or spasm can obscure palpation landmarks for lumbar facet joint injections or medial branch blocks. Surgeons approaching the posterior elements of the thoracolumbar spine also consider the longissimus plane during muscle-splitting exposure to reduce denervation and postoperative atrophy. Use this artwork in gross anatomy and kinesiology modules that cover posterior trunk musculature, erector spinae compartment anatomy, and thoracolumbar fascia mechanics, or in spine-focused chapters discussing extension-based low back pain and rehabilitation programming. It also fits patient education handouts that need a clean posterior map of superficial back muscles with the deeper paraspinals differentiated by color. Anatomical accuracy verified by SciePro's Medical Advisory Board.