EN | DE | PT Contact How to study Login Register

Intrinsic back muscles - want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 852,397 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Intrinsic back muscles

The intrinsic back muscles are part of the trunk musculature. They comprise a system of well-developed,  deep muscles, which collectively extend along the length of the vertebral column. They are located in an osteofibrous canal, bounded by the vertebrae, ribs and thoracolumbar fascia. These muscles are most deeply located muscles of the back, and are differentiated from the extrinsic muscles by the fact that they actually develop in the back during embryogenesis.

The intrinsic muscles of the back are extremely important in maintaining posture and movements of the vertebral column

Key Facts
Function Stabilization and movements of the vertebral column
Divisions Medial tract: spinalis and transversospinalis muscles
Lateral tract: sacrospinal, intertransverse, spinotransverse muscles
Deep neck muscles: rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis superior, obliquus capitis inferior muscles
Innervation Medial branches of the posterior rami of the spinal nerves

This article will describe all of the important anatomical facts about the intrinsic back muscles.

Overview

All intrinsic back muscles are innervated by the posterior branches of the spinal nerves.

Embryologically they derive from the dorsal part of the myotomes (epimere) which reside locally during the entire development for which reason they are also referred to as true or autochthonous back muscles.

In contrast, the extrinsic back muscles which are derived from the ventral part of the myotomes (hypomere), e.g. latissimus dorsi muscle and trapezius muscle, migrate into the trunk musculature subsequently (secondary back muscles).

The intrinsic back musculature is subdivided into a medial and lateral tract and the deep neck muscles.

Recommended video: Intrinsic muscles of the back: medial tract
Origins, insertions, innervation and functions of the medial tract of the intrinsic muscles of the back.

Medial tract

The medial tract extends between the spinal and transverse processes of the vertebrae. It is innervated by the medial branches of the posterior rami of the spinal nerves.

The medial tract can be further subdivided into the spinal, and transversospinal groups.

  • The spinalis muscles (spinalis thoracicis, spinalis cervicis, and spinalis capitis) and the interspinales muscles belong to the spinal group of medial intrinsic muscles. They connect the spinal processes of neighboring vertebrae. The spinalis muscle originates slightly laterally from the interspinales muscles.
  • The transversospinal groups comprises the short and long rotatores muscles, multifidus muscle and the semispinalis muscles. They all run diagonally from the transverse to spinal processes. The short rotatores muscles insert at the next higher vertebrae, the long rotatores muscles at the second higher vertebrae. The multifidus muscle skips 2-4 vertebrae, the semispinalis muscle even 4-7 vertebrae. Furthermore the semispinalis muscle has a robust insertion at the occipital bone.

Lateral tract

The lateral tract is a collection of long longitudinal muscles. It lies more superficially than the medial tract and inserts more laterally. It is innervated by the lateral branches of the posterior rami of the spinal nerves. The lateral tract can be further subdivided into sacrospinal, intertransverse and spinotransverse muscular groups.

  • The sacrospinal group consists of the longissimus muscle and iliocostalis muscle. Both share an origin tendon at the thoracolumbar fascia. They have numerous origins and insertions at the ribs and transverse processes. In addition the longissimus capitis muscle inserts at the mastoid process of the temporal bone.
  • The splenius muscles build the spinotransverse system. They originate at the spinal processes of the upper thoracic and cervical vertebrae and runs laterocranially.
  • The intertransverse group comprises the intertransversarii muscles and levatores costarum muscles. They extend between two neighboring transverse processes. The levatores costarum muscles are innervated by both the anterior and posterior branches of the spinal nerves (double innervation). Part of the intertransversarii muscles are even innervated only by anterior rami of the spinal nerves for which reason they do not count as intrinsic back muscles.
Recommended video: Intrinsic muscles of the back: lateral tract
Origins, insertions, innervation and functions of the lateral tract of the intrinsic muscles of the back.

Deep neck muscles

The deep neck muscles (suboccipital muscles) are innervated by the posterior branch of the first spinal nerve (C1), the suboccipital nerve, and are therefore considered as intrinsic back muscles. They consist of four paired muscles:

  • Rectus capitis posterior major muscle (spinal process of axisinferior nuchal line)
  • Rectus capitis posterior minor muscle (posterior tubercle of atlas → inferior nuchal line)
  • Obliquus capitis superior muscle (transverse process of atlas → inferior nuchal line)
  • Obliquus capitis inferior muscle (spinal process of axis → transverse process of atlas)

Function

The intrinsic back musculature is essential for the stabilization and movement of the vertebral column. Bilateral contraction stretches the body (dorsal extension), unilateral contraction bends the body to one side (lateral flexion). Rotation of the trunk is effected with the assistance of the oblique abdominal muscles.

The deep neck muscles support the movement of the atlanto-occipital joint. They have particularly many muscle spindles contributing to the proprioception of the head.

Intrinsic back muscles - want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 852,397 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1.Auflage, Urban & Fischer Verlag/Elsevier (2008), S.136-140
  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2.Auflage, Thieme Verlag (2007), S.142-149
  • K. Zilles/B.Tillmann: Anatomie, 1.Auflage, Springer Medizin Verlag (2010), S.168-178

Author & Layout:

  • Achudhan Karunaharamoorthy
  • Christopher A. Becker

Illustrators:

  • First Illustration Gallery - Yousun Koh
  • Second Illustration Gallery - Rebecca Betts, Yousun Koh
  • Third Illustration Gallery - Yousun Koh
  • Fourth Illustration Gallery - Yousun Koh
  • Fifth Illustration Gallery - Paul Kim
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

Related Atlas Images

Intrinsic muscles of the back

Superficial muscles of the back

Cervical spine

Continue your learning

Article (You are here)
Other articles
Well done!

Register now and grab your free ultimate anatomy study guide!

Create your free account.
Start learning anatomy in less than 60 seconds.