Spinal Muscles

All About Spinal Muscles

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 Spinal Column

CERVICAL MUSCLES	FUNCTION	NERVE
Sternocleidomastoid	Extends & rotates head, flexes vertebral column	C2, C3
Scalenus	Flexes & rotates neck	Lower cervical
Spinalis Cervicis	Extends & rotates head	Middle/lower cervical
Spinalis Capitus	Extends & rotates head	Middle/lower cervical
Semispinalis Cervicis	Extends & rotates vertebral column	Middle/lower cervical
Semispinalis Capitus	Rotates head & pulls backward	C1 – C5
Splenius Cervicis	Extends vertebral column	Middle/lower cervical
Longus Colli Cervicis	Flexes cervical vertebrae	C2 – C7
Longus Capitus	Flexes head	C1 – C3
Rectus Capitus Anterior	Flexes head	C2, C3
Rectus Capitus Lateralis	Bends head laterally	C2, C3
Iliocostalis Cervicis	Extends cervical vertebrae	Middle/lower cervical
Longissimus Cervicis	Extends cervical vertebrae	Middle/lower cervical
Longissimus Capitus	Rotates head & pulls backward	Middle/lower cervical
Rectus Capitus Posterior Major	Extends & rotates head	Suboccipital
Rectus Capitus Posterior Minor	Extends head	Suboccipital
Obliquus Capitus Inferior	Rotates atlas	Suboccipital
Obliquus Capitus Superior	Extends & bends head laterally	Suboccipital

THORACIC MUSCLES	FUNCTION	NERVE
Longissimus Thoracis	Extension, lateral flexion of vertebral column, rib rotation	Dorsal primary divisions of spinal nerves
Iliocostalis Thoracis	Extension, lateral flexion of vertebral column, rib rotation	Dorsal primary divisions of spinal nerves
Spinalis Thoracis	Extends vertebral column	Dorsal primary divisions of spinal nerves
Semispinalis Thoracis	Extends & rotates vertebral column	Dorsal primary divisions of spinal nerves
Rotatores Thoracis	Extends & rotates vertebral column	Dorsal primary divisions of spinal nerves

LUMBAR MUSCLES	FUNCTION	NERVE
Psoas Major	Flexes thigh at hip joint & vertebral column	L2, L3, sometimes L1 or L4
Intertransversarii Lateralis	Lateral flexion of vertebral column	Ventral primary division of spinal nerves
Quadratus Lumborum	Lateral flexion of vertebral column	T12, L1
Interspinales	Extends vertebral column	Dorsal primary divisions of spinal nerves
Intertransversarii Mediales	Lateral flexion of vertebral column	Dorsal primary divisions of spinal nerves
Multifidus	Extends & rotates vertebral column	Dorsal primary divisions of spinal nerves
Longissimus Lumborum	Extends & rotates vertebral column	Dorsal primary divisions of spinal nerves
Iliocostalis Lumborum	Extension, lateral flexion of vertebral column, rib rotation	Dorsal primary divisions of spinal nerves

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.

Extensive information regarding the muscles and their function can be found {muscles} here.

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