The Arm Lines are the “delivery systems” of the body. While the other lines we’ve discussed focus on moving your torso and legs through space, the Arm Lines are all about how you interact with the world—how you reach, pull, push, and grasp.

There are actually four distinct Arm Lines (two on the front, two on the back), and they act like a set of cables connecting your fingertips directly to your “core.”

1. The Physical Route: The Four Tracks

Thomas Myers divided these into “Deep” and “Superficial” layers for both the front and the back.

• Superficial Front Arm Line: Runs from the large chest muscles (Pectorals) down the inside of the arm to the palms and fingers. (Think: Pushing or hugging).
• Deep Front Arm Line: Starts at the ribs (Pectoralis minor), travels down the thumb-side of the arm to the thumb. (Think: Grasping or stabilizing).
• Superficial Back Arm Line: Starts at the trapezius (upper back/neck), travels over the shoulder, down the back of the arm to the back of the hand. (Think: Extending the arm or “shrugging”).
• Deep Back Arm Line: Starts at the shoulder blade (rotator cuff), down the pinky-side of the arm to the pinky. (Think: Fine motor control and rotation).

2. The Main Job: Connectivity to the Core

The most important thing to learn about Arm Lines is that the arms do not start at the shoulder.

• In the “Anatomy Chain” view, your arms start at your sternum (front) and your spine (back).
• The Connection: Your arm is physically woven into your torso. This allows the strength of your legs and core to be transmitted to your hands. When you throw a punch or open a heavy door, the power isn’t just coming from your bicep; it’s traveling through the Arm Lines from your center.

3. The “Victim/Culprit” Patterns of the Arm Lines

Because we live in a world of keyboards, phones, and steering wheels, the Arm Lines are often under a lot of “postural stress.”

• The Carpal Tunnel Culprit: Many people with wrist or hand pain (Victim) are actually suffering from a “short” Arm Line in the chest or shoulder (Culprit). If the fascia is tight at the chest, it pulls on the nerves and tissue all the way down to the wrist.
• Tennis/Golfer’s Elbow: Pain at the elbow is rarely an elbow problem. It’s usually a sign that the “Deep” Arm Lines are stuck, forcing the elbow to take all the mechanical stress of a grip or a swing.
• The Shoulder “Hike”: If the Superficial Back Arm Line is tight, it “tethers” the shoulder to the ear, leading to chronic neck tension.

4. How to “Feel” the Arm Lines

You can feel the continuity of these lines with a simple “Wall Stretch”:

1. The Setup: Stand sideways next to a wall. Extend your arm and place your palm flat against the wall at shoulder height, fingers pointing behind you.
2. The Connection: Slowly turn your chest away from the wall.
3. The Sensation: You won’t just feel a “muscle stretch” in your chest. You will likely feel a “tingling” or “pulling” sensation that travels all the way down through your bicep, your inner elbow, and into your palm. That “line” of tension is the Superficial Front Arm Line.

5. Why it’s Relevant to Your Daily Life

The Arm Lines are why your posture affects your hand strength.

• If your Superficial Front Line (the chest/stomach “wetsuit”) is tight and pulls your shoulders forward, it “slacks” the Arm Lines.
• This makes your grip weaker and your movements less precise.
• By “opening” the chest and “unzipping” the Arm Lines, you often find that hand fatigue and shoulder “clicks” disappear because the “track” is finally straight.