Anatomy of the Back - Muscles

Spine Anatomy: Muscles of The Back

The major muscles on the back are Psoas Major, Quadratus Lumborum and the Erector Spinae group.

The Psoas Major is located deep in the back and attaches directly to the front side of the vertebral bodies and deep on the inner side of the thigh bone on each side of body. It acts as a primary flexor muscle of the hip joint, helping to raise the lower limb at the hip joint towards the trunk.

The Quadratus lumborum lies next to the Psoas Major and attaches on the side of the vertebrae, on the transverse processes of the vertebraes, and along the top ridge of the pelvis bones located at the lower sides of the trunk. TheQuadratus Lumborum acts to side bend the trunk.

The erector Spinae group is made up of the Interspinales, Intertransversarii Mediales, Multifidi, Longissimus and Iliocostalis. The spinal extensor muscles lie behind the vertebral column, attach directly to the vertebrae, and stretch its entire length segment to segment. Each layer of muscles has specific subdivisions in the neck, midback, and lower back regions. They work as a group to help the back extend or bend backwards. The erector spinae muscles secondarily contribute to lateral bending and rotation of the spine.

We will look at the muscles that help stabilize the back on the anterior side of the body, or the abdominal muscle group on Friday.