Quadratus Lumborum: Action, Origin & Insertion

Instructor: Dan Washmuth

Dan has taught college Nutrition, Anatomy, Physiology, and Sports Nutrition courses and has a master's degree in Dietetics & Nutrition.

Have you ever sat for so long that your lower back started hurting? If so, there is a good chance that the pain was caused by the quadratus lumborum muscle, one of the many abdominal muscles. This lesson will teach about the origin, insertion, and action of this muscle.

Quadratus Lumborum

Is your quadratus lumborum muscle working properly? To find out, try this quick physical assessment test:

  1. Stand up straight, with your arms down at your sides
  2. Bend to your right side
  3. Bend to your left side
  4. Go into a slight back bend
  5. Forcefully exhale

If you were able to do all five of these steps, there is a good chance that your quadratus lumborum muscle is working just fine. The quadratus lumborum is a thick, square-shaped muscle located at the very back of the abdominal wall. In fact, this muscle is located so far back in the abdominal wall that it is often considered a back muscle.

The quadratus lumbroum muscle is a thick, square-shaped muscle located in the very back of the abdominal wall.

Quadratus Lumborum: Origin

The quadratus lumborum muscle originates from the iliac crest. The iliac crest is the top, outer part of the back hip bone. To feel your iliac crest, stand up and put your fingers on each side of your spine in your lower back. Now do a slight back bend and then feel around with your fingers. Do you feel the bone on each side of your lower back? That bone is your ilium and the top outer parts of the ilium is the iliac crest.

The quadratus lumborum muscle originates from the iliac crest of the ilium.
iliac crest

Quadratus Lumborum: Insertion

The quadratus lumborum muscle has several points of insertion. One of these points of insertion is the bottom part of the 12th rib on each side of the rib cage, which is the bottommost rib. Other parts of the quadratus lumborum insert or attach to the transverse processes of several lumbar vertebrae. The lumbar vertebrae are the vertebrae that are located in the lower back region of the spinal column. There are five total lumbar vertebrae (L1-L5) and the quadratus lumborum muscle attaches to the first four of these lumbar vertebrae (L1-L4)

Quadratus Lumborum: Action

Based on the physical assessment test you did at the beginning of the lesson, you probably already have a general idea of the actions of the quadratus lumborum muscle. To review, these actions include:

  • Side flexion of the spine/back: allows a person to bend to each side
  • Extension of the spine/back: allows a person to bend backwards
  • Assists with forceful exhalation: stabilizes the 12th rib when a person blows out forcefully

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