Erector spinae muscles
The erector spinae muscle group
|Origin||Spinous processes of T9-T12 thoracic vertebrae, medial slope of the dorsal segment of illiac crest|
|Insertion||spinous processes of T1 and T2 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|
|Latin||Musculus erector spinae|
|Anatomical terms of muscle|
||This section may be too technical for most readers to understand. (March 2016) (Learn how and when to remove this template message)|
The erector spinae is 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. The erector spinae is covered in the lumbar and thoracic regions by the thoracolumbar 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. Further up, it is subdivided into three columns. They gradually diminish in size as they ascend to be inserted into the vertebrae and ribs.
The erector spinae arises from the anterior surface of a broad and thick tendon. It is attached to the medial crest of the sacrum, to the spinous processes of the lumbar and the eleventh and twelfth thoracic vertebrae and the supraspinous 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 gluteus maximus.
The muscular fibers form a large fleshy mass that splits, in the upper lumbar region, into three columns, viz., a lateral (Iliocostalis), an intermediate (Longissimus), and a medial (Spinalis). Each of these consists of three parts, inferior to superior, as follows:
- iliocostalis lumborum has the lumbar part (where its insertion is in the 12th to 7th ribs)
- iliocostalis thoracis where its insertion runs from the last 6 ribs to the first 6 ribs.
- iliocostalis cervicis which runs from the first 6 ribs to the posterior tubercle of the transverse process of C6-C4.
The longissimus muscle is the intermediate and the largest of the three columns, it has three parts with different origin and insertion:
- longissimus thoracis originates from the sacrum, spinous processes of the lumbar vertebrae and transverse process of the last thoracic vertebra and inserts in the transverse processes of the lumbar vertebrae, erector spinae aponeurosis, ribs and costal processes of the thoracic vertebrae.
- longissimus cervicis originates from the transverse processes of T6-T1 and inserts in the transverse processes of C7-C2.
- longissimus capitis originates from the transverse processes of T3-T1 runs through C7-C3 and inserts in the mastoid process of the temporal bone.
The spinalis muscle is the most medial and the smallest column. It has three parts:
- spinalis thoracis which originates from the spinous process of L3-T10 and inserts in the spinous process of T8-T2.
- spinalis cervicis originates from the spinous process of T2-C6 and inserts in the spinous process of C4-C2.
- spinalis capitis is an inconstant muscles fibres that runs from the cervical and upper thoracic that then inserts in the external occipital protuberance.
|Lower thoracic vertebrae and ribs||I. lumborum|
|Upper thoracic vertebrae and ribs||I. thoracis||L. thoracis||S. thoracis|
|Cervical vertebrae||I. cervicis||L. cervicis||S. cervicis|
|Skull||L. capitis||S. capitis|
Examples of exercises by which the erector spinae can be strengthened for therapeutic or athletic purposes include, but are not limited to:
- Bent-over row
- Pull-up (exercise)
- Bridge (exercise)