Functional Anatomy Part 7-Intrinsic Back Muscles

In Parts 1, 2 and 5 of this mini-series I discussed the importance of developing glute, hamstring and calf  strength.  What do the glutes, hams and calves have in common with the muscles we will discuss today?  They are all part of the posterior chain.  A strong posterior chain is important in the maintenance of proper alignment, injury prevention, and athletic performance.  This article, along with parts 1, 2 and 5 will provide you with the resources necessary to make the posterior chain your strongest link.

The table below outlines origin, insertion and function of the intrinsic back muscles.  It looks daunting, I know, but don’t let it intimidate you, we’ll simplify it in the paragraphs that follow…

Overwhelmed?  Fear not, here’s the simplified version:

All of the muscles included in the chart, with the exception of quadtratus lumborum, combine to form the erector spinae.  The erector spinae runs the length of the back, from the sacrum to the base of the skull.  When working unilterally, the erectors laterally flex the spine and head (think side bending or bringing your ear to your shoulder).  When working bilaterally, they extend the spine and head (i.e., leaning backwards or arching your back).

Each portion of the erector spinae originates on a large tendon that attaches to the posterior sacrum, iliac crest, sacro-iliac ligaments, and lumbo-sacral spinous processes.  The erector spinae can be broken down into three different groups based on their insertion point:

  • The iliocostalis muscles (most lateral) insert on the ribs.
  • The spinalis muscles (most medial) insert on the spinous processes
  • The longissimus muscles (between the iliocostalis and spinalis muscles) insert on the transverse processes.

Each of these groups are further sub-divided depending on which area of the spine they act upon:

Considerations For Training:

How do you develop a strong and healthy back?  First, understand how the erectors function…When the erector spinae muscles all fire in unison, their net action is to extend the entire vertebral column. To work this function of the erector spinae there should be some variation of back extension in your programming. To isolate one side of the erector spinae, trunk extension must be combined with trunk rotation, so be sure to include exercises with this important combination as well.  The erector spinae also serves to stabilize the vertebral column, isometric back extensions will work this function.  Examples of each of these types of exercises are listed below.

Now that you know what exercises will train your back extensors, let me outline a few important points.  Bottom line, to develop strength and hypertrophy of the erectors, you have to deadlift!  Deadlifts allow you to move a greater load than any other back extension variation.  Also, when performing any of the exercises listed above, make sure that you avoid round back variations by MAINTAINING A NEUTRAL SPINE throughout your sets (unless you want a herniated disc).

Quadratus Lumborum

The primary function of the quadratus lumborum (QL) is lateral flexion of the trunk (along with the internal and external obliques).  It is also a major contributor to trunk stabilization, a strong QL allows you to squat, pull, and overhead press more weight.  However, if there is a side-to-side imbalance, this causes pelvic obliquity and contributes to lower back pain, so they must be trained appropriately.

Examples of QL exercises include:

  • Side bends (with weight in ONE hand, not two…if you use two, they essentially cancel each other out)
  • Windmills
  • Side Presses
  • Bent Presses
  • Saxon side bends

Considerations For Training:

In order to target your quadratus lumborum (and the internal/external obliques), you should include some lateral flexion exercises in your programming.  When performing these side bend variations, be sure to maintain a neutral pelvic alignment.  In addition, it is important to include flexibility exercises for the QL as it can result in lower back and pelvic alignment issues if it becomes too tight.

Well there you have it, functional anatomy and training of the intrinsic back muscles.  Be sure to combine the tips presented in this article with those in parts 1, 2, 5 and 6 when developing the posterior chain and core training components of your programs.

Next up:  Functional Anatomy Part 8-Upper Back Muscles…Check back in a few days…

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