Posterior Inferior Serratus, Posterior View

Description

Centered in the lower thoracic to upper lumbar back, the serratus posterior inferior is isolated as a paired, thin quadrilateral sheet deep to latissimus dorsi and superficial to the erector spinae mass. Its medial attachments track along the spinous processes and supraspinous ligaments around T11 to L2 via the thoracolumbar fascia, then the fibers run superolaterally to the inferior borders of ribs 9 through 12 near their angles. Inferiorly it blends with the posterior layer of the thoracolumbar fascia, while laterally it approaches the posterolateral thoracic wall where the rib cage begins to curve anteriorly. Small muscle, clear landmark. A posterior view like this matters because the serratus posterior inferior is routinely confused with neighboring layers during dissection and when teaching fascial planes of the thoracolumbar region. Palpation and dry needling discussions often cite its trigger points along the lower rib angles, where patients describe flank or posterolateral thoracic pain that can mimic costovertebral irritation or referred discomfort from lower rib dysfunction. For surgeons and radiologists, it also helps orient the relationship between the lower ribs, thoracolumbar fascia, and the muscle planes traversed in posterior or flank approaches to the retroperitoneum. Use this artwork in gross anatomy and kinesiology modules on thoracic wall musculature, accessory respiratory mechanics, and posterior trunk layering, or in atlas plates that differentiate latissimus dorsi, erector spinae, and the serratus posterior group. It also fits well in physiotherapy texts, pain medicine handouts, and surgical education materials discussing posterior incision planning along the 9th to 12th ribs and the lumbar fascial compartments. Anatomical accuracy verified by SciePro's Medical Advisory Board.