• Origin

Common tendon of origin from the sacrum

Iliac crest.

Spinous processes of lumbar vertebrae.

Transverse processes of lower thoracic vertebrae (T11–L2).

• Insertion

Transverse processes of all thoracic vertebrae.

Lower 9 to 10 ribs between the tubercles and angles.

• Agonist(s)

- Iliocostalis thoracis,

- Spinalis thoracis,

- Multifidus (synergist in spinal extension),

- Quadratus lumborum (in lateral flexion).

• Antagonist(s)

- Rectus abdominis,

- External and internal obliques,

- Psoas major (during spinal flexion).

• Function

Extends the vertebral column in the thoracic and lumbar regions.

Laterally flexes the spine to the same side.

Assists in maintaining erect posture.

Plays a role in spinal stability during lifting and movement.

TRIGGER POINT(S)

• Location

Commonly found along the length of the muscle near the lateral border of the thoracic vertebrae.

Particularly active between the lower thoracic and upper lumbar spine (T8–L3 region).

Trigger points often lie beneath or deep to the latissimus dorsi and erector spinae aponeurosis.

• Pain Referral Pattern

Pain may refer deep into the thoracic spine or radiate vertically along the back.

Discomfort may also be felt laterally into the flank or lower ribs.

Can mimic deep muscular back pain or discomfort after standing or walking for extended periods.

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Potential Causes

• Poor posture, especially prolonged seated or forward-bent positions.

• Repetitive lifting or twisting activities.

• Weak abdominal muscles leading to overuse of spinal extensors.

• Sudden or unguarded spinal extension movements.

• Chronic stress or tension held in the mid-back

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Prevention Tips

• Incorporate core strengthening to balance spinal load.

• Practice proper lifting mechanics and spinal alignment.

• Take breaks from prolonged sitting or static postures.

• Include gentle spinal extension and mobility exercises in routines.

• Address ergonomic factors contributing to poor posture or repetitive strain.