Erector spinae

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Erector spinæ
The relations of the kidneys from behind. (Sacrospinalis visible at bottom left.)
Deep muscles of the back. (Sacrospinalis visible at bottom right.)
Latin m. erector spinæ
Gray's subject #115 397
Origin: on the spines of the last four thoracic vertebræ
Insertion: both the spines of the most cranial thoracic vertebrae and the cervical vertebrae
Artery: lateral sacral artery
Nerve: posterior branch of spinal nerve
Action: extends the vertebral column
Antagonist: Rectus abdominis muscle
Dorlands/Elsevier m_22/12550616

The Erector spinæ (or Sacrospinalis in older texts), a bundle of muscles and tendons, and its prolongations in the thoracic and cervical regions, lie in the groove on the side of the vertebral column.

They are covered in the lumbar and thoracic regions by the lumbodorsal fascia, and in the cervical region by the nuchal fascia.

This large muscular and tendinous mass varies in size and structure at different parts of the vertebral column. In the sacral region it is narrow and pointed, and at its origin chiefly tendinous in structure.

In the lumbar region it is larger, and forms a thick fleshy mass which, on being followed upward, is subdivided into three columns; these gradually diminish in size as they ascend to be inserted into the vertebræ and ribs.

The erector spinae arises from the anterior surface of a broad and thick tendon, which is attached to the medial crest of the sacrum, to the spinous processes of the lumbar and the eleventh and twelfth thoracic vertebræ, and the supraspinal ligament, to the back part of the inner lip of the iliac crests and to the lateral crests of the sacrum, where it blends with the sacrotuberous and posterior sacroiliac ligaments.

Some of its fibers are continuous with the fibers of origin of the Glutæus maximus.

The muscular fibers form a large fleshy mass which splits, in the upper lumbar region into three columns, viz., a lateral, the Iliocostalis, an intermediate, the Longissimus, and a medial, the Spinalis.

Each of these consists from below upward, of three parts, as follows:

Lateral Column Intermediate Column Medial Column
Iliocostalis Longissimus Spinalis
I. lumborum L. dorsi S. dorsi
I. dorsi L. cervicis S. cervicis
I. cervicis L. capitis S. capitis

A useful mnemonic for remembering the erector spinae muscles is "I Love Sex" (lateral to medial).

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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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