The Spinal Muscles: An Extensive Guide

The spinal muscles and ligaments work in conjunction to help support the spine, maintain an upright posture, and control movements during activity and rest. The muscles are named based on shape, location, or combination. Further categorization factors include muscle functions like flexion, extension, or rotation. Skeletal muscle is a form of striated muscle tissue that is voluntarily controlled by the somatic nervous system. Striated means it is striped in appearance. Most skeletal muscles are attached to bones by collagen fibers known as tendons.

Vertebral Muscle Types	Location
Forward flexors	Anterior
Lateral flexors	Lateral
Rotators	Lateral
Extensors	Posterior

It has the fastest contraction rate of all muscles. Before muscle/s contracts, a nerve impulse starts in the brain and runs through the spinal cord to the muscle. For the muscles to contract and work properly, they need energy/fuel. Mitochondria produce Adenosine triphosphate chemical cells that are needed for energy. Adenosine triphosphate is made as the mitochondria burn glucose or sugar. The blood vessels deliver the oxygen and nutrients the mitochondria need to maintain a steady supply of adenosine triphosphate.

The Posterior Cervical and Upper Thoracic Spinal Muscles

1. Semispinalis Capitus – controls the head rotation and backward pulls
2. Iliocostalis Cervicis – extends the cervical vertebrae
3. The Longissimus Cervicus – extends the cervical vertebrae
4. Longissimus Capitus – controls the head’s rotation and backward pulls
5. Longissimus Thoracis – controls the extension/lateral flexion of the vertebral column and rib rotation
6. Iliocostalis Thoracis – controls the extension/lateral flexion of the vertebral column and rib rotation
7. Semispinalis Thoracis – extends and rotates the vertebral column

Muscles of the Spinal Column

Cervical muscles

Cervical Muscles	Function	Nerve
Sternocleidomastoid	Extends rotates the head and flexes the vertebral column	C2, C3
Scalenus	Flexes and rotates the neck	Lower cervical
Spinalis Cervicis	Extends and rotates the head	Middle/lower cervical
Spinalis Capitus	Extends and rotates the head	Middle/lower cervical
Semispinalis Cervicis	Extends and rotates the vertebral column	Middle/lower cervical
Semispinalis Capitus	Rotates the head and pulls backward	C1-C5
Splenius Cervicis	Extends the vertebral column	Middle/lower cervical
Longus Colli Cervicis	Flexes the cervical vertebrae	C2-C7
Longus Capitus	Flexes the head	C1-C3
Rectus Capitus Anterior	Flexes the head	C2, C3
Rectus Capitus Lateralis	Bends the head laterally	C2, C3
Iliocostalis Cervicis	Extends the cervical vertebrae	Middle/lower cervical
Longissimus Cervicis	Extends the cervical vertebrae	Middle/lower cervical
Longissimus Capitus	Rotates the head and pulls backward	Middle/lower cervical
Rectus Capitus Posterior Major	Extends and rotates the head	Suboccipital
Rectus Capitus Posterior Minor	Extends the head	Suboccipital
Obliquus Capitus Inferior	Rotates the atlas	Suboccipital
Obliquus Capitus Superior	Extends and bends the head laterally	Suboccipital

Thoracic Muscles

Thoracic muscles	Function	Nerve
Longissimus Thoracis	Extension, lateral flexion of the vertebral column, and rib rotation	Dorsal primary divisions of the spinal nerves
Iliocostalis Thoracis	Extension, lateral flexion of the vertebral column, and rib rotation	Dorsal primary divisions of the spinal nerves
Spinalis Thoracis	Extends the vertebral column	Dorsal primary divisions of the spinal nerves
Semispinalis Thoracis	Extends and rotates the vertebral column	Dorsal primary divisions of the spinal nerves
Rotatores Thoracis	Extends and rotates the vertebral column	Dorsal primary divisions of the spinal nerves

Lumbar muscles

Lumbar muscles	Function	Nerve
Psoas Major	Flexes the thigh at the hip joint and the vertebral column	L2, L3, sometimes L1 or L4
Intertransversarii Lateralis	Lateral flexion of the vertebral column	The ventral primary division of the spinal nerves
Quadratus Lumborum	Lateral flexion of the vertebral column	T12, L1
Interspinales	Extends the vertebral column	Dorsal primary divisions of the spinal nerves
Intertransversarii Mediales	Lateral flexion of the vertebral column	Dorsal primary divisions of the spinal nerves
Multifidus	Extends and rotates the vertebral column	Dorsal primary divisions of the spinal nerves
Longissimus Lumborum	Extends and rotates the vertebral column	Dorsal primary divisions of the spinal nerves
Iliocostalis Lumborum	Extension, lateral flexion of the vertebral column, and rib rotation	Dorsal primary divisions of the spinal nerves

Muscle Fascia Fibrous Tissue

• Fascia is the thickened connective tissue that surrounds a muscle or muscle group. Superficial fascia is directly under the skin.
• Epimysium surrounds the skeletal muscle.
• Perimysium is the sheath that groups the muscle fibers into bundles.
• Endomysium is another type of connective tissue that sheaths each muscle fiber.

The cause of back pain and spinal muscle spasm/s can be caused by overuse, automobile accident, personal, work, or sports injury. The root cause of muscle spasm/s is usually a consequence of an injury to a structure within the lumbar spine. If there have been one or more episodes of muscle spasm in the low back, chances are it will re-occur. The muscles in the low back work together with the abdominal muscles. The spinal muscles add stability by maintaining an erect spine and maintaining balance.

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Back Pain Specialist