Back Muscles: Core Form & Function

Erector Spinae (Spinal Erectors)

Erector Spinae (Spinal Erectors
This uniquely excellent image is from

This uniquely excellent image is from

  • The erectors consist of three groups of muscles running the length of either side of the spine.
  • The spinalis group is most medial (closest to spine); the longissimus is the next group; the iliocostalis is the most lateral group.
  • The erectors are deep, located beneath two other layers of muscles and covered by fascia. (Core Walking)
  • The erectors help to maintain erect posture; stabilize the spine during flexion; and assist in side bending and spinal rotation.
  • The erectors together act as “powerful extensors to promote the return of the back to the erect position… primarily responsible for the extension of the back (straighten the spine) as well as more specific movements such as extension of the neck and sideward movements of the head.” (

Multifidus Muscles

Multifidus Muscles
  • The multifidus muscles are a series of deep muscles that run the length of the spine.
  • They stabilize vertebrae as well as assist in spinal rotation and extension.
  • With those who have experienced back pain, knowledge of the multifidus muscles can be key to learning to recruit the core for stabilization.
  • See here for more information.

Weak Multifidus Activity Correlated with Back Pain

[Study] results showed that low back pain subjects, especially those with chronic pain, displayed significantly smaller multifidus muscle activity as compared to healthy subjects during the coordination exercises, indicating that over the long term, back pain patients have a reduced ability to voluntarily recruit the multifidus muscles in order to maintain a neutral spine position…. When multifidus function is poor, one will be more susceptible to back injuries. – Core Concepts

Unique Design

The Multifidus… has a unique design that provides support as well as keeps us upright by providing scaffolding for the vertebral column. Unlike most muscles, when the multifidus is on stretch (when we bend forward) it gets stronger. Generally, if a muscle is lengthened it has a tendency to lose strength. Obviously this Multifidus is operating under different rules. – USA Synchro