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Erector spinæ
	The relations of the kidneys from behind. (Sacrospinalis visible at bottom left.)
	Deep muscles of the back. (Erector spinae 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
Actions	extends the vertebral column
Antagonist	Rectus abdominis muscle

The Erector spinæ is a muscle of the back in humans and other animals. It is also known as sacrospinalis in older texts. A more modern term is extensor spinae,^[1] though this is not in widespread use. The name of the muscle is pronounced e-rec-tor speen-aye, or e-rec-tor spinae-ee.

It is really not just one muscle, but a bundle of muscles and tendons. It is paired and runs more or less vertically. It extends throughout the lumbar, thoracic and cervical regions, and lies in the groove to the side of the vertebral column.

Erector spinae is covered in the lumbar and thoracic regions by the lumbodorsal fascia, and in the cervical region by the nuchal ligament.

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

[edit] Training

The erector spinae can be strengthened for therapeutic or athletic purposes by the following exercises:

[edit] Additional images

Right hip bone. Internal surface.	Diagram of a transverse section of the posterior abdominal wall, to show the disposition of the lumbodorsal fascia.	The posterior divisions of the sacral nerves.	Transverse section, showing the relations of the capsule of the kidney.
Surface anatomy of the back.	Photograph of the surface of a human back.	Lumbar triangle

[edit] References

^ Terminologia Anatomica, 1999.

[edit] External links

-596967347 at GPnotebook
SUNY Figs 01:05-03 - "Intermediate layer of the extrinsic muscles of the back, deep muscles."
erector+spinae+muscles at eMedicine Dictionary
ithaca.edu

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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 within it may be outdated.

[0] Terminologia Anatomica, 1999.

[1]

Contents

[edit] Training

[edit] Additional images

[edit] References

[edit] External links