Muscles of The Spine

Keith Bridwell, MD Orthopaedic Surgeon Washington University School of Medicine St. Louis, MO, USA

Muscles are named according to their shape, location, or a combination. They are further categorized according function such as flexion, extension, or rotation. Muscles and ligaments work together to support the spine, hold it upright, and control movement during rest and activity.

Types of Vertebral Muscles	General Location
Forward flexors	Anterior
Lateral flexors	Lateral
Rotators	Lateral
Extensors	Posterior

Skeletal muscle is striated (striped) in appearance. It is innervated, under voluntary control, and has the fastest contraction rate of all muscle. Prior to a muscle contracting, a nerve impulse originates in the brain and travels through the spinal cord to the muscle.

Energy is needed for the muscle to contract (work). Mitochondria (cellular level) produce ATP (adenosine triphosphate), a chemical cells need for energy. ATP is produced as the mitochondria burn glucose (sugar). Blood vessels deliver the oxygen and nutrients the mitochondria needs to provide a steady supply of ATP.

Muscles of the Posterior Cervical and Upper Thoracic Spine 1. Semispinalis Capitus (head rotation/pulls backward) 2. Iliocostalis Cervicis (extends cervical vertebrae) 3. Longissimus Cervicus (extends cervical vertebrae) 4. Longissimus Capitus (head rotation/pulls backward) 5. Longissimus Thoracis (extension/lateral flexion vertebral column, rib rotation) 6. Iliocostalis Thoracis (extension/lateral flexion vertebral column, rib rotation) 7. Semispinalis Thoracis (extends/rotates vertebral column)

Muscles of the Spinal Column

Muscle Fascia
Fascia is thickened connective tissue that envelops a muscle or a group of muscles. Superficial fascia is found directly under the skin. Epimysium is the fascia closest to the muscle. Perimysium divides the muscle into facicles – muscle fibers. Endomysium is another type of connective tissue that covers each muscle fiber.