📖 Static demo — read-only snapshot
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Erector Spinae Group
Group of muscles (iliocostalis, longissimus, spinalis) running along the vertebral column. Primary trunk extensors. Thoracic fibers contribute 50% of total extensor moment at L4-L5; at upper lumbar levels, thoracic fibers contribute 70-86%.
Draft95%
Anatomy
- Origin
- Iliocostalis lumborum: ilium, erector spinae aponeurosis, L1-4 transverse/accessory processes; Longissimus thoracis: ilium, lumbar intermuscular aponeurosis, erector spinae aponeurosis
- Insertion
- Iliocostalis: costal elements of L1-4, lower ribs; Longissimus: accessory and transverse processes of lumbar vertebrae, lower thoracic vertebrae and ribs
- Action
- Bilateral: trunk extension, maintains upright posture; Unilateral: lateral flexion; portions have appreciable potential to generate torque about all three orthopedic axes
- Innervation
- Iliocostalis: lateral branches of lumbar dorsal rami; Longissimus: intermediate branches of lumbar dorsal rami
- Blood Supply
- Lumbar arteries, posterior intercostal arteries
Movements (9)
| Movement | Joint | Role | Notes |
|---|---|---|---|
| Lumbar Lateral Flexion | Lumbar Intervertebral Joints | Primary | Ipsilateral; iliocostalis force direction ~±90° from sagittal |
| Thoracic Extension | Thoracic Intervertebral Joints | Primary | Thoracic portions: 64.9 ± 27.1% MVC in prone extension [De Ridder 2013] |
| Thoracic Lateral Flexion | Thoracic Intervertebral Joints | Primary | Ipsilateral |
| Lumbar Extension | Lumbar Intervertebral Joints | Primary | Thoracic fibers: 50% of L4-L5 moment, 70-86% at upper lumbar levels |
| Cervical Extension | Cervical Intervertebral Joints (C2-C7) | Secondary | Cervical portion (longissimus cervicis) |
| Lumbar Rotation | Lumbar Intervertebral Joints | Secondary | Portions have appreciable rotational torque potential |
| Hip Extension | Hip Joint (Coxofemoral) | Stabilizer | Maintains trunk extension |
| Hip Flexion | Hip Joint (Coxofemoral) | Stabilizer | Eccentric control of trunk |
| Knee Extension | Tibiofemoral Joint | Stabilizer | Trunk stability during squatting |
Exercises (94)
Sources
- Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation — Anatomy of Erector Spinae Group — origin, insertion, action, innervation
- Muscles: Testing and Function with Posture and Pain — Manual muscle testing for Erector Spinae Group