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Erector Spinae — Spinalis

Muscles

The spinalis is the smallest and most medial column of the erector spinae group, running between spinous processes and representing the spinal extension force closest to the axis of rotation. It is the least clinically significant of the three erector columns in isolation but contributes to the overall erector spinae function in trunk extension and lower crossed syndrome.

Origin, Insertion, Action, Innervation

  • Origin: Spinous processes of L1–L2 and T11–T12 (spinalis thoracis), spinous process of C7 and sometimes T1 (spinalis cervicis), with a variable spinalis capitis that may blend with semispinalis capitis
  • Insertion:
  • Spinalis thoracis: Spinous processes of T1–T8 (upper thoracic)
  • Spinalis cervicis: Spinous process of C2 (axis) — variable and often poorly developed
  • Spinalis capitis: Blends with semispinalis capitis (between the superior and inferior nuchal lines)
  • Action:
  • Primary: Extension of the vertebral column (bilateral contraction)
  • Lateral flexion (minor — its proximity to the midline limits its moment arm for lateral flexion)
  • Innervation: Dorsal rami of the spinal nerves (segmental)

Palpation Guide

  • Client position: Prone with arms at the sides.
  • Landmark sequence:
  1. Spinalis is the most medial erector column, lying immediately lateral to the spinous processes.
  2. In the thoracic region, palpate along the "gutter" between the spinous processes and the longissimus column — spinalis occupies this narrow space approximately 1–2 cm lateral to the spinous processes.
  3. The muscle is thin and blends with longissimus laterally and the transversospinalis muscles (multifidus, rotatores) deeply.
  4. Spinalis is not reliably distinguishable from the surrounding muscles by palpation alone in most individuals.
  • Tissue feel: Thin and difficult to isolate. In the thoracic gutter close to the spinous processes, you are palpating a blend of spinalis, multifidus, and rotatores. The tissue feels moderately firm, and individual muscle identification is not clinically necessary.
  • Confirmation test: Ask the client to extend the spine. The entire medial erector column contracts. There is no way to selectively activate spinalis independent of the other erector columns.
  • Common errors:
  • Attempting to isolate spinalis from multifidus or rotatores — these deep muscles overlap with spinalis in the paravertebral gutter and cannot be distinguished by palpation.
  • Treating spinalis as clinically distinct from the erector group — for practical purposes, the erector spinae are treated as a functional unit in the lumbar and thoracic regions.

Trigger Point Referral

  • Common TrP locations: TrPs in the medial paravertebral gutter at the thoracic level are attributed to the combined spinalis/multifidus/rotatores layer rather than spinalis alone.
  • Referral pattern: TrPs near the thoracic spinous processes refer locally to the midline back and may radiate laterally along the ribs.
  • Clinical significance: Midline thoracic back pain with localized tenderness at the spinous process level that does not reproduce with facet loading tests (extension) or rib spring tests suggests paravertebral soft tissue TrPs — including the spinalis layer.

Trigger point referral diagram — coming soon

Image coming soon. For visual reference, see [Spinalis at TriggerPoints.net](http://www.triggerpoints.net/muscle/spinalis).

Clinical Notes

Common conditions:
  • Contributes to the erector spinae group's role in conditions/lower-crossed-syndrome and conditions/low-back-pain as part of the "tight" posterior group.
  • Spinalis thoracis hypertonicity contributes to reduced thoracic mobility — when shortened bilaterally, it restricts thoracic flexion and contributes to a rigid, hypokyphotic thoracic spine. This is the opposite of the expected thoracic hyperkyphosis and is sometimes seen in clients with exaggerated lumbar lordosis compensating for a flat thoracic spine.
  • Spinalis cervicis (when well-developed) contributes to cervical extension and is part of the deep cervical extensor group that maintains cervical lordosis.
What you'll typically find:
  • The medial paravertebral gutter in the thoracic region is a common area of tenderness that students attribute broadly to "the erectors." Spinalis is part of this picture but is not individually identifiable or treatable.
  • In practice, treatment of the medial paravertebral gutter addresses spinalis, multifidus, and rotatores simultaneously — this is appropriate because they function together.
Treatment effects:
  • The medial paravertebral gutter responds to sustained compression and gentle cross-fiber techniques applied perpendicular to the spine. Use the thumb or fingertips to work in the narrow space between the spinous processes and the longissimus column.
  • Post-treatment, segmental spinal mobility often improves — the client may feel that individual vertebral segments "unlock."
Cautions:
  • Avoid heavy direct pressure on the spinous processes themselves — work in the gutter lateral to the spinous processes, not on them.
  • In the cervical region, deep medial paravertebral work requires awareness of the vertebral artery and the greater occipital nerve.
Clinical pearl:
  • The medial paravertebral gutter (where spinalis lives) is the transition zone between the global extensors (erector spinae) and the local stabilizers (multifidus, rotatores). When you treat this zone with specific segmental techniques (compression on each level, moving superiorly), you are addressing both systems simultaneously. This is more effective than broad stripping of the erector mass alone.

Assessment

Manual muscle testing:
  • Tested as part of the erector spinae group — trunk extension. Isolation of spinalis is not clinically feasible.
Stretch test:
  • Trunk flexion: Same as the other erector columns. Seated forward flexion assesses overall erector extensibility.
Related special orthopedic tests:
  • Posteroanterior spring test on spinous processes — pain may indicate underlying facet pathology or paravertebral soft tissue involvement

Muscle Groups

Erector spinae group (anatomical — three columns): Medial paravertebral muscles (anatomical — deep to erector group):

Related Muscles

Synergists for trunk extension: Antagonists:

Key Takeaways

  • Spinalis is the smallest and most medial erector column — not individually palpable or treatable in isolation, but contributes to the erector group's function.
  • Treatment of the medial paravertebral gutter addresses spinalis, multifidus, and rotatores simultaneously — specific segmental techniques here are more effective than broad erector stripping.
  • Functionally inseparable from the erector group in clinical practice — assess and treat as part of the three-column system.

Related

Sources

  • Travell, J. G., & Simons, D. G. (1999). Myofascial pain and dysfunction: The trigger point manual (Vol. 2, 2nd ed.). Williams & Wilkins.
  • Biel, A. (2014). Trail guide to the body (5th ed.). Books of Discovery.
  • Vizniak, N. A. (2010). Muscle manual. Professional Health Systems.
  • Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2023). Clinically oriented anatomy (9th ed.). Wolters Kluwer.
  • Magee, D. J., & Manske, R. C. (2021). Orthopedic physical assessment (7th ed.). Elsevier.
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