Corpus: Erector spinae muscle

The erector spinae muscle is the back musculature lying on the spinal column which, unlike many other muscle groups, did not migrate in during embryonic development, but was created next to the spinal column and has not changed its location.

The autochthonous back muscles lie in an osteofibrous canal, which is formed by the fascia thoracolumbalis, the arcuate laminae as well as the spinous and transverse processes of the vertebrae and partly by the ribs.

The autochthonous back muscles are divided into a medial and a lateral tract. The exact division of the back muscles into the individual cord systems is not standardised in the anatomical literature, which is not surprising given the complexity of the back musculature.

Medial tract[Bearbeiten]

This tract includes

Interspinal and spinal system[Bearbeiten]

These muscles connect the spinous processes of neighbouring vertebrae.

• Musculi interspinales
• Musculi spinales
• Musculus rectus capitis posterior major
• Musculus rectus capitis posterior minor

Transversospinal system[Bearbeiten]

These muscles extend from the transverse process of a vertebra to the spinous process of a proximal vertebra or to the occiput and can skip some segments. They include:

• Musculi semispinales
• Musculi multifidi
• Musculi rotatores

Lateral tract[Bearbeiten]

This tract includes:

Intertransverse system[Bearbeiten]

These muscles connect the transverse processes of neighbouring vertebrae. They include:

• Musculi intertransversarii
• Musculus obliquus capitis superior

Sacrospinal system[Bearbeiten]

These muscles originate from the sacral bone, the spinous processes of the lumbar vertebrae, the iliac crest and the thoracolumbar fascia. They can skip segments and insert at the ribs and the spinal column.

• Musculi iliocostales
• Musculus longissimus

Spinotransvertebral system[Bearbeiten]

These muscles extend from the spinous processes to the transverse processes of proximal vertebrae. They include:

• Musculus splenius cervicis
• Musculus splenius capitis
• Musculus obliquus capitis inferior

Rippenhebemuskeln[Bearbeiten]

Contrary to their name, these muscles pull the vertebral bodies downwards. They cause lateral flexion when contracted on one side and dorsal extension when contracted on both sides:

• Musculi levatores costarum breves
• Musculi levatores costarum longi

The main function of the autochthonous back muscles is to straighten the spine and keep the head upright. When contracted unilaterally, particularly in the medial and lateral tracts, the muscle groups can also rotate the spine or tilt it to one side.

Innervation is provided by the dorsal branches of the spinal nerves, which are divided into a medial and lateral branch. The medial tract is innervated by the medial branch, the lateral tract by the lateral branch.

The autochthonous back muscles lie in the thoracic and lumbar region between the superficial and deep leaflets of the thoracolumbar fascia, which also serves as the point of origin for some muscles. In the cervical region, it is surrounded by the fascia nuchae, which separates the autochthonous musculature from the muscles that migrated in during embryonic development.

Tension in the autochthonous back muscles, e.g. caused by static problems or functional disorders of the spine, can lead to back pain.