Posterior Superior Serratus

Description

Positioned in the upper thorax, the serratus posterior superior lies deep to the rhomboid minor and rhomboid major, with its thin muscular slips running inferolaterally from the lower cervical and upper thoracic spinous processes toward the posterior aspects of ribs 2 to 5. Medially, its origins align with the midline over the vertebral column, while laterally the slips approach the rib angles where the ribs begin to curve anteriorly. The scapulae sit superficial and lateral to the vertebral column, and the medial borders of the scapulae provide the attachment line for the rhomboids that overlie the target muscle. Bony landmarks remain clear: cervical vertebrae superiorly, upper thoracic vertebrae inferiorly, and the posterior rib cage framing the field. Teaching this muscle benefits from a posterior dissection-style view because serratus posterior superior is often misidentified as an intercostal layer or dismissed as part of the rhomboid plane; seeing it explicitly deep to the rhomboids clarifies the true layering of the posterior thoracic wall. Clinically, that distinction matters when localizing upper thoracic myofascial pain near the medial scapular border and when planning regional anesthesia or trigger-point injection, where a too-superficial approach lands in rhomboid and a deeper trajectory risks pleura near the rib angles. Small muscle, high stakes. Use this artwork in gross anatomy lab manuals to teach the superficial-to-deep sequence after trapezius reflection, in rehabilitation and sports medicine texts discussing scapulothoracic pain patterns, and in surgical or pain medicine references that map safe needle paths relative to ribs and posterior thoracic musculature. Anatomical accuracy verified by SciePro's Medical Advisory Board.