The Erector Spinae muscle actually consists of three columns of muscles, the Iliocostalis, Longissimus, and Spinalis, each running parallel on either outer side of the Thoracic Vertebra and extending from the lower back of the skull all the way down to the Pelvis. The Erector Spinae provides resistance that assists in the control action of bending forward at the waist as well as acting as powerful extensors to promote the return of the back to the erect position. During full flexion (i.e., when touching fingertips to floor), the Erector Spinae Muscles are relaxed and strain is borne entirely by ligaments of back, however on the reversal of the movement, the Erector Spinae in conjunction with the Hamstring muscles and Gluteus Maximus muscles (buttocks) is primarily responsible for the extension of the back (straighten the spine) as well as more specific movements such as the extension of the neck Vertebrae and sidewards movement of the head.
Muscles that make up the Erector Spinae
The furthest from the thoracic Vertebra of all the Erector Spinae muscles the Iliocostalis muscle is chiefly responsible with assisting extension and laterally flex of the vertebral column, maintaining erect posture as well as bending the vertebral column to the same side. The Iliocostalis Muscles origin attachment point is the Lumbosacral Fascia, the inferior 6 ribs (thoracis) and ribs 3 to 6 (cervicis). The insertion attachment points are the angles of ribs 7 to 12 (lumborum and thoracis); transverse processes of cervical vertebrae C6–C4 (cervicis).
THE LONGISSIMUS DORSI MUSCLES
The Longissimus Dorsi Muscle the longest of the back and is made up of 3 distinct parts, the Capitis, the Cervicis and the Thoracis.
- The Capitis Muscles are used to hold the head erect as well as rotating toward the same side of the muscle that is contracting. The origin attachment points are from the lateral of the top four thoracic vertebrae and it’s insertion point is mastoid process of the skull.
- The Cervicis Muscles are responsible for bending the top of the neck and assist in keeping the cervical spine erect. The origin point from narrow tendons from the lateral of the top four thoracic vertebrae and it’s insertion points are from the lateral of the cervical vertebra 2 through till 6.
- The Thoracis Muscles assists in the motion of backward and sidewards bending, keeping the spine erect and pulling the ribs downward to help with breathing. It’s origin attachment point is from the Lumbosacral Fascia and it’s two insertion points are medially the transverse processes of the vertebrae, and laterally the lower nine or ten ribs, just where they begin to curve away from the spine.
THE SPINALIS MUSCLES
The Spinalis muscles are the closest to the thoracic Vertebra of all the Erector Spinae muscles and consists of two muscles, the Cervicis and the Thoracis.
- The Spinalis Cervicis origin points are from the lower ligamentum nuchae: spinous processes of C6 or C7 and the insertion point of attachment is the spinous process of the axis. The Spinalis Cervicis Muscles work closely with the Spinalis Thoracis muscle to extend and laterally flex vertebral column such as when you try to stand tall to increase your height by extending the gap between your vertebrae.
- The Spinalis Thoracis origin points are from the inner portion of the Lumbosacral Fascia as well as from the spinous processes of T11 to L2. It’s insertion points are most if not all of the spinous processes of the upper thoracic vertebrae from T2 to T8. The Spinalis Thoracis muscle work closely with the Spinalis Cervicis muscles to extend and laterally flex vertebral column such as when you try to stand tall to increase your height by extending the gap between your vertebrae.