From which structures does iliocostalis lumborum originate?

From which structures does iliocostalis lumborum originate?

• A. Angles of the lower ribs (7-12)
• B. Transverse processes of lumbar vertebrae
• C. Spinous processes of lumbar vertebrae
• D. Iliac crest, sacrum, and thoracolumbar fascia

Answer: (D)

The iliocostalis lumborum starts from a broad posterior anchor: the iliac crest, sacrum, and the thoracolumbar fascia. This sturdy origin gives the muscle a stable base to reach upward to its insertion on the lower ribs and upper lumbar transverse processes, allowing it to extend the spine and bend it laterally. The angles of the lower ribs and the transverse processes of the lumbar vertebrae are locations of its attachment (insertion), not where it originates, and the spinous processes of the lumbar vertebrae are not the origin for this muscle.

The iliocostalis lumborum starts from a broad posterior anchor: the iliac crest, sacrum, and the thoracolumbar fascia. This sturdy origin gives the muscle a stable base to reach upward to its insertion on the lower ribs and upper lumbar transverse processes, allowing it to extend the spine and bend it laterally. The angles of the lower ribs and the transverse processes of the lumbar vertebrae are locations of its attachment (insertion), not where it originates, and the spinous processes of the lumbar vertebrae are not the origin for this muscle.