Arm Lines

The Arm Lines are a set of four Fascial Lines described by Thomas Myers that comprise the upper extremity (SOURCE-1). Each line, or Fascial continuity, envelops and interconnects a distinct set of Muscles which have unique roles in arm motion and joint stability.

The four Fascial Lines contained within the arms are listed below. For specifics regarding each continuity, including scientific justification, assessment and treatment, see their respective page:

• Superficial Front Arm Line

• Deep Front Arm Line

• Superficial Back Arm Line

• Deep Back Arm Line

Interrelation

The Arm Lines are both interrelated with eachother through “Crossovers” and with other Fascial Lines through their attachment to the torso. Compensatory patterns displayed in the arm lines may be attributed to insufficient support at their Thorax connection, with the following lines often implicated (SOURCE-1):

• Superficial Front Line

• Superficial Back Line

• Spiral Line

• Deep Front Line

Crossovers

Certain tissues belong to more than one Arm Line, forming a “Crossover” which improves stability between lines (SOURCE-1):

Teres Major

The Teres Major is included in the Superficial Front Arm Line along with the Latissimus Dorsi and through its attachment to the Scapula actually forms a crossover from the Deep Back Arm Line.

Deltoid to Brachialis

While the Deltoid to Lateral Intermuscular Septum connection defines the Superficial Back Arm Line , there are fibres that are extended from the muscle to the local Brachialis. This creates a crossover between the SBAL and the Deep Front Arm Line.

Biceps Brachii

The Biceps Brachii, in particular the Short Head of Biceps , are a major site on the Deep Front Arm Line . However, the proximal attachment of the Long Head of Biceps is a natural extension from the Supraspinatus making it a part of the Deep Back Arm Line . Consequently, the Biceps form a crossover between the two deep Fascial Lines which affords a great deal of stability to the arm. At their distal end, the Bicipital Aponeurosis blends with the wrist flexors forming yet another crossover with the Superficial Front Arm Line.

Forearm

Distal of The Elbow , the DFAL follows the attachments of the Short Head of Biceps and the Supinator where it meets a crossover from the Superficial Back Arm Line - the Pronator Teres at their shared attachment on the Radius.

References

1. Myers, T. W. (2009). Anatomy trains: Myofascial meridians for manual and movement therapists (2nd ed.). Elsevier.