Muscle:Thoracolumbar Paraspinal/Deep

The deep thoracolumbar paraspinal muscles — the Semispinalis Thoracis, Multifidi, and Rotatores — form the transversospinal group and lie deep to the erector spinae. Their trigger points (TrPs) produce a characteristically severe, persistent aching "bone" pain that is worrisome and disabling and is felt deep in the spine. These muscles are primarily stabilisers and fine-movement regulators of the vertebral column rather than prime movers. They are the deepest paraspinal layer and therefore the most technically demanding to examine and inject. They are covered by the superficial erector spinae, which must frequently be treated first to allow access to the deep layer.

Contents

• Anatomy
• Referred Pain Patterns
  • Semispinalis Thoracis
  • Multifidi
  • Rotatores
• Activation and Perpetuating Factors
• Clinical Examination
• Differential Diagnosis
• Treatment
• Satellite Trigger Points
• Related Pages
• References

Anatomy

All paraspinal muscles are innervated by branches of the dorsal primary divisions of the spinal nerves. The medial branch of each dorsal primary division innervates the deepest muscles at the level of the nerve exit — in the lower thoracic and lumbar regions, the nerve, the rotator muscle, and the tip of the spinous process with the same number are all at the same level. The lumbar multifidi are arranged so that the fibres moving a particular segment are innervated by the nerve of that same segment (unisegmental innervation of each lumbar segmental band).

Semispinalis Thoracis

• Attachments: Medially and above near the base of vertebral spinous processes; laterally and below to transverse processes; fibres cross at least five vertebrae; extends caudally to T10
• Position: Outermost (most superficial) of the deep paraspinal group; overlies the multifidi; lies deep to longissimus thoracis

Multifidi

• Attachments: Medially and above near the base of spinous processes; laterally and below to transverse processes; fibres cross 2–4 segments throughout the thoracic and lumbar spine; sometimes extend to S4
• Lumbar multifidi: Divided by distinct cleavage planes into five segmental bands; each band arises from a lumbar spinous process and is innervated unisegmentally
• Function: Principal action is posterior sagittal rotation (extension without posterior translation — no translatory action); EMG evidence supports a role as stabilisers rather than prime movers; the deep transversospinal muscles act as dynamic ligaments adjusting small movements between individual vertebrae
• Extent: Fills the multifidus triangle of the sacrum; covered by tendinous extensions of the more superficial longissimus and iliocostalis

Rotatores

• Attachments: Short rotatores — adjacent vertebrae; long rotatores — span one segment throughout the spine; rotatores ordinarily do not include sacral segments (only multifidi extend across sacral segments)
• Position: Deepest layer of the paraspinal muscles; lie against the laminae of the vertebrae; attach at the base of each spinous process
• Function: Act as dynamic ligaments adjusting small movements between individual vertebrae; when acting unilaterally, the deep group rotates vertebrae to the contralateral side

Referred Pain Patterns

Semispinalis Thoracis Pain

The pain patterns of the semispinalis thoracis correspond closely to those of the longissimus fibres at the same segmental level — see Muscle:Thoracolumbar_Paraspinal/Superficial for the segmental pain maps.

The severe aching "bone" pain from TrPs in the deep group generally is persistent, worrisome, and disabling — the quality of pain from any of the three deep muscles is similar.

Multifidi Pain

Midthoracic TrPs (around T4–5):

• Pain centred on the spinous process region adjacent to the TrP — essentially midline or immediately paramedian

Lumbar TrPs (L1–L5):

• Pain centred around the adjacent spinous process
• May also refer pain anteriorly to the abdomen — readily misjudged as visceral in origin
• The pain is usually a unilateral, extremely disagreeable, steady ache deep in the spine; becomes bilateral as muscles on both sides become involved
• The patient is often convinced the pain originates in the bony spine, not in the muscles — a characteristic subjective feature
• Patient may point to a one-sided bulging of the long muscles of the low back
• Finds little relief by changing position (distinguishing feature from mechanical disc pain, which typically has a position of relief)

S1-level TrPs:

• Project pain downward to the coccyx
• Render the coccyx hypersensitive to pressure (referred tenderness)
• The condition is often diagnosed as coccygodynia — multifidus TrPs at S1 are the myofascial explanation

Rotatores Pain

• Pain felt essentially in the midline throughout the length of the thoracolumbar spine, at the spinous process adjacent to the TrP
• Referred tenderness to tapping on the spinous process adjacent to a TrP — this is the osteopathic sign of articular dysfunction at that vertebra
• Only deep palpation of the muscles can determine from which side the midline pain arises

Important clinical note: T&S report that Kellgren's experimental deep paraspinal injections showed that deep muscles were more likely than the superficial group to refer pain anteriorly to the abdomen. At the L5 level, deep muscle stimulation referred pain down the posterolateral aspect of the thigh and leg — a pattern that mimics lumbar radiculopathy.

Activation and Perpetuating Factors

Deep paraspinal TrPs tend to occur in patients with either:

• Excessive lumbar lordosis (hyperlordosis) — deep lumbar paraspinal TrPs
• Absent lumbar lordosis — deep lumbar paraspinal TrPs
• Marked thoracic kyphosis — deep thoracic paraspinal TrPs

The same general activation factors as the superficial group apply — see Superficial Paraspinal: Activation and Perpetuating Factors. Additionally:

• An L4–L5 lateral disc herniation produces tightness of the left L4–L5 multifidus muscle, causing a segmental motion block

Clinical Examination

Patient Presentation

Active TrPs in the deep paraspinal muscles:

• Cause guarded movements
• Restrict side-bending, rotation, and hyperextension of the trunk
• The pain is felt deep in the spine and the patient is often convinced the bony spine is the source — this subjective conviction of "bony origin" is characteristic of deep muscle TrPs

Spinous Process Flattening

The hallmark examination finding of deep paraspinal involvement is a flat area or slight hollow spanning one to three vertebrae in the normal smooth spinous process curve, visible and palpable during forward flexion.

The flattening indicates restricted segmental movement at that level. Its extent correlates roughly with the depth and extent of muscle involved:

• Single-level flattening → rotatores TrP (single-level articular dysfunction)
• Two to three vertebrae → multifidus TrPs (two to three adjacent levels of articular dysfunction)
• Four to six vertebrae → semispinalis TrPs (four to six segmental levels of dysfunction); the apex segment is exquisitely tender to palpation

Trigger Point Examination

Positioning: Patient recumbent in the semiprone position (as for superficial muscles) or seated leaning slightly forward to flex the spine.

Step 1 — Spinous process survey:

• Tap or press on the tips of successive spinous processes to elicit tenderness
• Locate the flat area in the spinous process curve during flexion — this indicates the probable TrP level
• If two or three spinous processes are tender, expect TrPs on at least one side at each level of tenderness

Step 2 — Deep palpation:

• When a spinous process in the flat area is hypersensitive, palpate deep musculature on each side
• Apply firm pressure in the groove between the spinous process and the longissimus muscle on each side
• For the rotatores (deepest layer): direct deep finger pressure along the side of the spinous process toward the underlying laminae — locate a spot of maximum tenderness

Note: A taut band will not be palpable through the overlying superficial paraspinals. Identification depends on focal deep tenderness and reproduction of the referred pain pattern.

Articular Dysfunction Extent

Use the depth of the flat area and spinous process tenderness pattern to estimate depth of involvement and number of articular levels involved. Single-level midline tenderness over one spinous process after clearing the overlying muscles suggests rotator involvement; multi-level tenderness with a smooth curve flattening over several processes suggests multifidus or semispinalis involvement.

Differential Diagnosis

The deep paraspinal TrPs are the primary myofascial mimic of:

Condition	Key distinguishing features
Lumbar facet (zygapophysial) joint pain	Schneider emphasised that multifidus TrPs closely mimic lumbar facet and sacroiliac syndromes, and that L4–L5 lateral disc herniation produces tightness of the L4–L5 multifidus causing a segmental motion block; referred pain from lumbar zygapophysial joints overlaps with multifidus pain patterns; distinguish by articular provocation and diagnostic blocks
Coccygodynia	Multifidus TrPs at S1 render the coccyx hypersensitive to pressure via referred tenderness — this is the mechanism for many cases diagnosed as coccygodynia; the coccyx tenderness disappears after TrP inactivation
Visceral disease (abdominal)	Lumbar multifidus TrPs (L1–L5) may refer pain anteriorly to the abdomen — readily misjudged as visceral; deep paraspinal muscles are more likely than superficial to refer anteriorly
Lumbar radiculopathy	Deep paraspinal stimulation at L5 can refer pain down the posterolateral thigh and leg mimicking L5/S1 radiculopathy; distinguish by objective neurological deficit (reflex, sensory, motor)
Primary scoliosis	Compensatory S-curve from structural asymmetry (leg length, hemipelvis) with group paraspinal dysfunction may be misinterpreted as primary scoliosis; correct the structural asymmetry and reassess — see Paraspinal Corrective Actions

The general differential (radiculopathy, visceral disease, osteoarthritis, fibromyalgia, fat lobules, sacroiliac dysfunction) is shared with the superficial group — see Superficial Paraspinal: Differential Diagnosis for the full table.

Treatment

Trigger Point Release — Deep Group

Spray and stretch (multifidi and rotatores):

1. Patient seated; spine flexed and simultaneously rotated, turning the chest toward the side of the involved muscle
2. Operator applies sweeps of vapocoolant spray in a diagonal pattern over the deep muscles (Fig. 48.7 in T&S)
3. Operator takes up the slack that develops and repeats several times to achieve full normal range of motion

Postisometric relaxation (PIR):

1. Patient looks first toward the contralateral side while the examiner resists any attempt to turn the torso
2. Patient then relaxes and turns toward the affected side
3. Reciprocal inhibition is added if the patient gently voluntarily assists rotation toward the affected side

Key requirement: A tight contralateral iliocostalis thoracis may need to be released first (by adding sweeps of spray over that muscle as in the erector spinae technique) before full release of the deeper muscles can be achieved.

Manual release for articular dysfunction: Many manual release techniques directed toward spinal articular dysfunctions are as effective for releasing tense deep spinal muscles as they are for releasing restricted joint movement — the two effects are inseparable at the deep paraspinal level.

Trigger Point Injection — Deep Group

See Concept:Trigger_Point_Injection.

Injection of deep paraspinal TrPs is technically demanding and is indicated when the more accessible stretch and spray, PIR, and TrP pressure release have failed.

Technique:

• Needle directed caudally (not upward) and slightly medially — aimed toward the base of the spinous process, not between the spinous processes
• For the rotatores (deepest layer): needle at least 5 cm (2 in) long; directed somewhat caudally and medially, nearly parallel to the long axis of the spine; aimed toward the base of the spinous process but not between the spinous processes
• The caudal slant is required because of the shingle-like overlap of the laminae
• Penetration to a depth greater than the laminae is unnecessary and undesirable
• This angle eliminates the possibility of introducing the needle between the ribs into the pleural cavity, or between the vertebrae into the epidural space
• TrP injection is followed immediately by repetition of stretch and spray, moist heat, and active range of motion

When to inject vs. spray and stretch

• Multiple TrPs spread throughout the paraspinal musculature → start with stretch and spray
• Few refractory TrPs remaining, or TrPs lying deep in the paraspinal musculature → injection is best

Satellite Trigger Points

The deep paraspinal group is more likely than the superficial group to show isolated muscle involvement. The superficial paraspinals more commonly accumulate associated TrPs in functionally related muscles.

The same satellite relationships and thoracolumbar junction triad (erector spinae, psoas, quadratus lumborum) described for the superficial group apply — see Superficial Paraspinal: Satellite Trigger Points.

Related Pages

• Muscle:Thoracolumbar_Paraspinal/Superficial — Iliocostalis thoracis, iliocostalis lumborum, longissimus thoracis; referred pain patterns, activation, structural assessment, corrective actions
• Concept:Paraspinal_Corrective_Actions — Full corrective actions programme for all paraspinal TrPs
• Muscle:Quadratus_Lumborum — Thoracolumbar junction triad; assists spinal extension
• Muscle:Psoas — Thoracolumbar junction triad
• Muscle:Serratus_Posterior — Assists spinal extension; associated TrPs
• Concept:Trigger_Point_Injection — Deep paraspinal injection technique; epidural and pneumothorax precautions
• Concept:Perpetuating_Factors — Structural asymmetry, lordosis/kyphosis

References

• Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1: The Upper Half of Body. 2nd ed. Baltimore: Williams & Wilkins; 1999. Chapter 48.