Transversospinales

The transversospinales are a deep group of intrinsic muscles located in the posterior aspect of the spine. These muscles originate from the transverse processes of the vertebrae and insert onto the spinous processes of superior vertebrae. The group is typically divided into three distinct layers based on the length of their fibers: the semispinalis, multifidus, and rotatores. The semispinalis muscles are the longest, spanning multiple vertebral segments. The multifidus muscles are intermediate in length, typically crossing two to four segments. The rotatores muscles are the shortest, usually spanning only one or two segments.

The primary actions of the transversospinales muscles include extension, lateral flexion, and rotation of the vertebral column. Their deep location and arrangement allow for fine, controlled movements and contribute significantly to spinal stability. They work in conjunction with other back muscles to maintain posture and resist external forces acting on the spine. Dysfunction or weakness in these muscles can contribute to lower back pain and other spinal issues. These muscles are innervated by the posterior rami of spinal nerves.