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Iliocostalis Lumborum Muscle

(Sample Lesson)

Muscle Description

The iliocostalis lumborum muscle lies lateral to the longissiumus muscle group and deep to the serratus posterior muscle. It s a part of the erector spinae muscles that function to straighten and laterally flex the vertebrae column.

Iliocostalis Lumborum Muscle - superficial view
Iliocostalis Lumborum Muscle - deep view

Muscle Attachments

Origin: medial and lateral sacral crests; medial iliac crest.

Insertion: angles of ribs 6 or 7 – 12.

Iliocostalis Lumborum Muscle - attachments (origin and insertion)

Muscle Actions

Bilaterally (both) muscle contraction:
Extend the vertebral column.

Flexion of the vertebral column

Unilateral (one) muscle contraction:
Laterally flex the vertebral column
to the same side.

Lateral flexion of the vertebral column

Muscle Nerve Supply

Dorsal primary rami of thoracic and lumbar spinal nerves (T7 to L3).