Erector Spinae Muscle Anatomy

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Origin	Spinalis Spinalis capitis: spinous processes of C6-T2 and the nuchal ligament Spinalis cervicis: spinous processes of C7-T1 and the nuchal ligament Spinalis thoracis: spinous processes of T11-L2 vertebrae Longissimus Longissimus capitis: transverse processes of C4-T4 Longissimus cervicis: transverse processes of T1-T4 Longissimus thoracis: dorsal surface of the sacrum and median sacral crest, medial surface of the posterior superior iliac spine, and transverse processes of L1-L5 Iliocostalis Iliocostalis cervicis: angles of ribs 3-6 Iliocostalis thoracis: angles of ribs 7-12 Iliocostalis lumborum: medial end of the iliac crest, lateral crest of the sacrum, and thoracolumbar fascia
Insertion	Spinalis Spinalis capitis: the occiput Spinalis cervicis: spinous processes of C2 or C3 vertebrae Spinalis thoracis: spinous processes of T2-T8 Longissimus Longissimus capitis: posterior edge of the mastoid process Longissimus cervicis: posterior tubercle of C2-C6 transverse processes Longissimus thoracis: transverse processes of vertebrae T1-T12 and the dorsal aspect of ribs 3-12 (between the rib’s angle and tubercle) Iliocostalis Iliocostalis cervicis: posterior tubercles of the transverse processes of C4-C6 Iliocostalis thoracis: transverse process of C7 and angles of ribs 1-6 Iliocostalis lumborum: transverse processes of L1-L4 and angles of ribs 4-12
Action	Bilateral contraction: extension of the trunk, neck, and vertebral column Unilateral contraction: lateral flexion of the trunk, neck, and vertebral column
Innervation	Posterior rami of corresponding spinal nerves
Blood Supply	Spinalis Dorsal branches of posterior intercostal arteries, deep cervical artery, vertebral artery, and dorsal branches of lumbar arteries Longissimus Vertebral artery, deep cervical artery, occipital artery, deep branch of the transverse cervical artery, supreme intercostal artery, posterior intercostal arteries, subcostal arteries, lumbar arteries, and lateral sacral arteries Iliocostalis Dorsal branches of segmental arteries, including posterior intercostal, subcostal, lumbar, and lateral sacral arteries

Last updated: 8 June 2026 Estimated Reading Time: 22 min

Location & Overview

The erector spinae is a large, long group of muscles located at the posterior aspect of the body. The erector spinae group consists of the spinalis, longissimus, and iliocostalis. These three muscles run parallel to the spine, from the sacrum to the neck. The erector spinae muscles are responsible for extension and lateral flexion movements, as well as spinal stabilisation.^[1]

The spinalis muscle is located in the middle and upper back, as well as the neck.^[2,3,4] It is the most medial of the erector spinae muscles, blending laterally with the longissimus. The spinalis muscle is composed of three sections: the capitis, cervicis, and thoracis. The capitis is the most superior of these three sections, the cervicis is in the middle, and the thoracis is the most inferior.^[2]

The longissimus is the largest and longest muscle of the erector spinae group. It is located between the spinalis and iliocostalis. The longissimus is divided into three sections: the longissimus capitis, longissimus cervicis, and longissimus thoracis. This muscle extends from the sacrum to the edge of the mastoid process.^[5,4,2]

The iliocostalis muscle is the most lateral muscle in this group. It is divided into three sections based on their points of origin: iliocostalis cervicis, iliocostalis thoracis, and iliocostalis lumborum. These sections span from the lumbar region to the cervical region of the spine.^[2,4,6]

erector spinae muscle — Here, we can see all three of the erector spinae muscles together.

erector spinae individual muscles highlighted — Here, we can see each of the erector spinae muscles highlighted in different colours for clarity. The spinalis is highlighted in yellow, the longissimus in purple, and the iliocostalis in green.

spinalis muscle — Here, we can see the spinalis muscle by itself.

spinalis sections highlighted — Here, we can see the spinalis sections highlighted in different colours. The capitis is highlighted in yellow, the cervicis in purple, and the thoracis in green.

longissimus muscle — Here, we can see the longissimus muscle by itself.

longissimus sections highlighted — Here, we can see the longissimus sections highlighted in different colours. The capitis is highlighted in yellow, the cervicis in purple, and the thoracis in green.

iliocostalis muscle — Here, we can see the iliocostalis muscle by itself.

iliocostalis sections highlighted — Here, we can see the iliocostalis sections highlighted in different colours. The cervicis is highlighted in yellow, the thoracis in purple, and the lumborum in green.

Origin & Insertion

The erector spinae muscles each have their own distinct origins and insertions, varying across their respective sections and among individuals. The erector spinae group of muscles includes the spinalis, longissimus, and iliocostalis muscles.

The spinalis muscle is the most medial muscle of the erector spinae and consists of three distinct sections: spinalis capitis, spinalis cervicis, and spinalis thoracis. The spinalis capitis originates from the spinous processes of C6 to T2 and the associated nuchal ligament and inserts onto the medial and inferior aspect of the occiput.^[3] The occiput is a section of bone located at the back of the skull, and the nuchal ligament is a ligament on the back of the neck that runs from the occiput to C7. The spinalis cervicis begins at the nuchal ligament and the spinous processes of the lower cervical to upper thoracic vertebrae (C7 and T1) and inserts onto the spinous processes of the second or third cervical vertebra (C2 or C3).^[3] Lastly, the spinalis thoracis originates on the spinous processes of T11-L2 and inserts onto the spinous processes of the upper thoracic vertebrae T2-T8.^[2]

spinalis capitis origins and insertions — Displayed here are the origin and insertion points of the spinalis capitis muscle. It originates on the spinous processes of C6 to T2 and the associated nuchal ligament and inserts onto the occiput. The muscle’s origins are marked in red, and its insertions are marked in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

spinalis cervicis origins and insertions — This image shows the origin and insertion sites of the spinalis cervicis section. The origin is the nuchal ligament and the spinous processes of C7 and T1, and the insertion is the spinous processes of C2 and C3. The red markings indicate the muscle’s origins, while the blue markings represent its insertions.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

spinalis thoracis origins and insertions — Here, we can observe the origin and insertion points of the spinalis thoracis muscle. The origin is the spinous processes of T11-L2, and the insertion is T2-T8. The origins are highlighted in red, while the insertions are coloured blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

nuchal ligament — Here, we can see the nuchal ligament. The nuchal ligament is also known as the ‘ligamentum nuchae’ in Latin. This ligament is a point of origin for the spinalis cervicis and spinalis capitis sections. The nuchal ligament is located at the back of the neck and extends from the external occipital protuberance to the seventh cervical vertebra.

spinalis origins and insertions — Here, we can see all of the spinalis sections’ origins and insertions together. The capitis has a yellow highlight around it, the cervicis has a purple highlight, and the thoracis has a green highlight.

The longissimus muscle, the intermediate column of the erector spinae, also has three sections: longissimus capitis, longissimus cervicis, and longissimus thoracis. The longissimus capitis originates from the transverse processes of C4 to T4 vertebrae and inserts at the posterior edge of the mastoid process. The mastoid process is a bony projection on the temporal bone, at the posterior base of the skull. You can feel the bump of the mastoid process on the skull close to the area behind your earlobe. The longissimus cervicis originates from the transverse processes of T1 to T4 vertebrae and inserts at the posterior tubercle of C2 to C6 transverse processes.^[2] The longissimus thoracis originates from the dorsal surface of the sacrum and its median sacral crest, the medial surface of the posterior superior iliac spine, and the transverse processes of L1 to L5 vertebrae. The insertion is on the transverse processes of T1 to T12 vertebrae and the dorsal aspect of ribs 3 to 12, between the rib angle and tubercle.^[4]

longissimus capitis origins and insertions — This image shows the points of origin and insertion of the longissimus capitis segment. The origin is on the transverse processes of C4 to T4 vertebrae, and it inserts at the posterior edge of the mastoid process. The origin points are marked in red, and the insertion points are highlighted in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

longissimus cervicis origins and insertions — The points of origin and insertion of the longissimus cervicis are displayed in this picture. The origin is on the transverse processes of T1 to T4, and it inserts on the transverse processes of C2 to C6. The origin points are marked in red, and the insertion points are marked in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

longissimus thoracis origins and insertions — This image shows the origins and insertions of the longissimus thoracis section. It originates on the dorsal surface of the sacrum and its median sacral crest, the medial surface of the posterior superior iliac spine, and the transverse processes of L1 to L5 vertebrae. It inserts at the transverse processes of T1 to T12 vertebrae and the dorsal aspect of ribs 3 to 12, between the rib angle and tubercle. The origins are highlighted in red, and the insertions are highlighted in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

longissimus origins and insertions — Here, we can see all of the longissimus sections’ origins and insertions together. The capitis has a yellow highlight around it, the cervicis has a purple highlight, and the thoracis has a green highlight.

The iliocostalis muscle, the lateral column of the erector spinae, includes the iliocostalis cervicis, iliocostalis thoracis, and iliocostalis lumborum. The iliocostalis cervicis has its origin at the angles of ribs 3 to 6 and inserts at the posterior tubercle of the transverse processes of vertebrae C4 to C6. The iliocostalis thoracis originates at the angles of the bottom six ribs and inserts at the transverse process of vertebra C7 and the angles of the top six ribs.^[2] The iliocostalis lumborum originates at the medial end and dorsal segment of the iliac crest and the lateral crest of the sacrum, inserting at the lumbar transverse processes of L1 to L4, the angles of ribs 4 to 12, and the thoracolumbar fascia. The thoracolumbar fascia is a large, diamond-shaped connective tissue structure located in the lower back, spanning from the lower thoracic to the upper lumbar spine. It encases the muscles of the lower back.^[4]

iliocostalis cervicis origins and insertions — This image shows the origins and insertions of the iliocostalis cervicis section. The origin is on the angles of ribs 3 to 6, and it inserts on the transverse processes of C4 to C6. The origins are highlighted in red, and the insertions are highlighted in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

iliocostalis thoracis origins and insertions — This image displays the origins and insertions of the iliocostalis thoracis section. The origin is the angles of the bottom six ribs, and it inserts on the transverse process of C7 and the angles of the top six ribs. The origins are highlighted in red, and the insertions are highlighted in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

iliocostalis lumborum origins and insertions — This image shows the origins and insertions of the iliocostalis lumborum section. The origin is on the medial end and dorsal segment of the iliac crest and the lateral crest of the sacrum. It inserts onto the lumbar transverse processes of L1 to L4, the angles of ribs 4 to 12, and the thoracolumbar fascia. The origins are highlighted in red, and the insertions are highlighted in blue.
Note: For the sake of simplicity, only the left side of the muscle is displayed here. However, the origins and insertions are duplicated on the right-hand side.

thoracolumbar fascia — Highlighted in green, we can see the thoracolumbar fascia, an insertion point of the iliocostalis lumborum section. The thoracolumbar fascia is a large, diamond-shaped complex of connective tissue situated in the lower back region.

iliocostalis origins and insertions — Here, we can see all of the iliocostalis sections’ origins and insertions together. The cervicis has a yellow highlight around it, the thoracis has a purple highlight, and the lumborum has a green highlight.

Action & Function

The erector spinae, consisting of the spinalis, longissimus, and iliocostalis muscles, plays an important role in various actions of the spine, neck, and trunk. The effects of these muscles depend on whether unilateral or bilateral contractions occur, with unilateral referring to a single side contracting and bilateral involving simultaneous contractions on both sides.^[1,4,2]

The spinalis muscle is divided into thoracis, cervicis, and capitis sections, and each section influences its corresponding vertebral region. For the thoracis segment, unilateral contraction results in lateral flexion of the trunk, while bilateral contraction leads to trunk extension.^[1,2] The cervicis and capitis sections of the spinalis primarily affect neck movement, with bilateral contractions extending the neck and unilateral contractions causing ipsilateral lateral flexion.^[1,4]

The longissimus muscle, with its capitis, cervicis, and thoracis segments, also influences both trunk and neck movements. Bilateral contractions lead to extension of the trunk and neck, whereas unilateral contractions result in lateral flexion. The longissimus capitis affects movements of the neck and upper thoracic vertebrae, whereas the longissimus thoracis influences trunk movements.^[1,5,2]

The iliocostalis muscle, with its cervicis, thoracis, and lumborum sections, contributes to movements of the trunk and vertebral column, with unilateral contractions causing lateral flexion and bilateral contractions leading to extension. The cervicis segment of the iliocostalis also provides weak support for lateral flexion at the base of the neck during unilateral contractions and weak extension at the base of the neck during bilateral contractions.^[1,2,6]

Image of a person demonstrating trunk extension. — This image shows an example of trunk extension, which involves extending the torso backward. The opposite of trunk extension is trunk flexion. Bilateral contraction of the relevant parts of the erector spinae will result in this action. However, only the parts of the erector spinae that cross the trunk will be able to extend it.

Image of a person demonstrating neck extension. — This image demonstrates neck extension, which involves extending the neck backward. The opposite of neck extension is neck flexion. Bilateral contraction of the relevant parts of the erector spinae will result in this action. However, only the parts of the erector spinae that cross the neck will be able to extend it.

Image of a person demonstrating the movement of trunk lateral flexion. — This image demonstrates trunk lateral flexion, which involves bending the torso to the side. Unilateral contraction will result in lateral flexion. However, only the parts of the erector spinae that cross the trunk will be able to laterally flex it.

Image of a person demonstrating the movement of neck lateral flexion. — This image demonstrates neck lateral flexion, which involves bending the neck to the side. Unilateral contraction will result in this action. However, only the parts of the erector spinae that cross the neck will be able to laterally flex it.

Innervation

The erector spinae muscles are innervated segmentally by branches of the posterior rami of the corresponding spinal nerves. This means that each region of the muscle group receives its nerve supply from spinal nerves close to that part of the vertebral column, rather than from one single named peripheral nerve. This pattern is typical of the intrinsic, or deep, muscles of the back.^[7,8]

The spinalis muscle receives a regional nerve supply from posterior rami across the cervical, thoracic, and upper lumbar regions. The spinalis thoracis is supplied mainly by posterior rami from thoracic and upper lumbar spinal nerves, while the spinalis cervicis and spinalis capitis are supplied by posterior rami from cervical and upper thoracic spinal nerves.^[7,8]

The longissimus muscle is also innervated by posterior rami of the corresponding spinal nerves. The longissimus capitis and longissimus cervicis are supplied by branches from cervical spinal nerves, while the longissimus thoracis is supplied segmentally by posterior rami in the thoracic and lumbar regions. In the lumbar region, the longissimus is supplied by intermediate branches of the posterior rami, while the iliocostalis is supplied by lateral branches.^[9,10]

The iliocostalis muscle is innervated by the lateral branches of the posterior rami of the spinal nerves. Like the other erector spinae muscles, its nerve supply follows a segmental pattern, with each vertebral level contributing to the part of the muscle located in that region.^[6,4]

spinal nerves anatomy — Pictured here is a cross-section of a lumbar vertebra. One of the labelled parts is the ‘dorsal ramus’, which is also known as the ‘posterior ramus’. Each segment of the erector spinae muscles receives innervation from the posterior ramus of the corresponding spinal nerve. In other words, the part of the muscle aligned with a specific spinal segment is innervated by that specific spinal nerve’s posterior ramus.

Blood Supply

The blood supply to the erector spinae muscles is regional and segmental because the group extends from the sacral and lumbar regions to the thoracic, cervical, and cranial regions. The upper parts of the group receive contributions from arteries in the neck, including the vertebral artery, deep cervical artery, occipital artery, and deep branch of the transverse cervical artery. More inferiorly, the thoracic, lumbar, and sacral regions receive blood from dorsal branches of nearby segmental arteries.^[8,9]

The spinalis muscle receives blood from vessels near the regions it crosses. In the cervical region, muscular branches from the vertebral and deep cervical arteries contribute to its supply, with possible contribution from descending branches of the occipital artery. In the thoracic region, the spinalis thoracis is supplied mainly by dorsal branches of the posterior intercostal arteries. In the lower thoracic and upper lumbar region, dorsal branches of the lumbar arteries can also contribute.^[8]

The longissimus receives blood from several arteries along its length. In the neck, its arterial supply comes from branches of the vertebral artery, deep cervical artery, occipital artery, and deep branch of the transverse cervical artery. In the thoracic region, it receives blood from dorsal branches of the posterior intercostal arteries, with the upper thoracic region also receiving contribution from the supreme intercostal artery. The lower thoracic region is supplied by dorsal branches of the posterior intercostal and subcostal arteries, while the lumbar and sacral regions receive blood from dorsal branches of the lumbar arteries, the arteria lumbalis ima when present, and dorsal branches of the lateral sacral arteries.^[10]

The iliocostalis receives blood mainly through dorsal branches of segmental arteries that supply the deep muscles of the back. In the thoracic region, dorsal branches of the posterior intercostal arteries divide into medial and lateral musculocutaneous branches, with the lateral branches supplying the iliocostalis and nearby tissues. More inferiorly, the iliocostalis receives blood from dorsal branches of the posterior intercostal, subcostal, lumbar, and lateral sacral arteries. This arrangement reflects the long vertical course of the muscle and its position as the most lateral part of the erector spinae group.^[11,9]

References

[1] Standring S. (2015). Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 41st Edn. Amsterdam: Elsevier.
[2] Henson B, Kadiyala B, Edens MA. Anatomy, Back, Muscles. (Updated 2022 Aug 25). In: StatPearls (Internet). Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537074/
[3] Greiner TM, Bedford ME, Walker RA. Variability in the human m. spinalis capitis and cervicis: frequencies and definitions. Ann Anat. 2004 Apr;186(2):185-91. doi: 10.1016/S0940-9602(04)80039-6. PMID: 15125051.
[4] Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincott Williams & Wilkins; 2017.
[5] Cramer, G. D., & Darby, S. A. (2014). Clinical anatomy of the spine, spinal cord, and ANS (3rd ed.). St. Louis: Elsevier. ISBN 9780323079549.
[6] Chaitow, Leon, and DeLany, Judith (2011), Clinical Application of Neuromuscular Techniques, Volume 2 (Second Edition), Oxford: Churchill Livingstone, ISBN 978-0-443-06815-7
[7] Dalley AF, Agur AMR. Moore’s Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
[8] Standring S. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 42nd ed. Amsterdam: Elsevier; 2021.
[9] Dalley AF II, Agur AMR. Moore’s Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
[10] Standring S, editor. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 42nd ed. London: Elsevier; 2021.
[11] Standring S, editor. Gray’s anatomy: the anatomical basis of clinical practice. 42nd ed. Amsterdam: Elsevier; 2021.

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