overview

Primary Stabilizers: Multifidus, Quadratus Lumborum

Multifidus

• Origin: Sacrum, posterior superior iliac spine (PSIS), transverse processes

• Insertion: Spinous processes (2–4 vertebrae above)

• Function: Stabilizes spine; assists rotation

Quadratus Lumborum

• Origin: Iliac crest

• Insertion: 12th rib, transverse processes (L1–L4)

• Function: Lateral flexion; stabilizes pelvis; assists breathing

Main Extensors: Erector Spinae Group

Iliocostalis Lumborum

• Origin: Iliac crest, sacrum

• Insertion: Lower ribs, transverse processes

• Function: Extends and laterally flexes spine

Longissimus Thoracis

• Origin: Sacrum, lumbar transverse processes

• Insertion: Ribs, thoracic vertebrae

• Function: Extends and laterally flexes spine

Spinalis

• Origin: Spinous processes (lumbar/thoracic)

• Insertion: Upper thoracic/cervical spinous processes

• Function: Assists spinal extension

Core/Lumbar Connection: Psoas Major

Psoas Major

• Origin: Vertebral bodies and transverse processes (T12–L5)

• Insertion: Lesser trochanter of femur

• Function: Hip flexion; stabilizes lumbar spine

Functional Role

• Posture: Maintains upright alignment

• Spinal Protection: Stabilizes and supports vertebrae

• Movement Control: Allows controlled flexion, extension, and rotation