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The Five Primary Shoulder Girdle Muscles

Anatomy

These are essential in stabilizing the shoulder so it can support lifting, throwing, and many other functional arm and shoulder movements. These five muscles, the Serratus Anterior, Pectoralis Minor, Levator Scapulae, Rhomboids and Trapezius also play a key role in shoulder strength and injury prevention. 

The shoulder girdle muscles enable the shoulder to perform four types of movements — elevation (shrugging – upper trap), depression (pressing shoulders away from ears – lower trap), protraction (pushing shoulders forward – pec minor and serratus anterior) and retraction (pulling shoulders back – mid trap and rhomboid). 

Let’s take a specific look at each of these: 

The Serratus Anterior muscles (your “wings”), are large muscles that wrap along your rib cage like talons and attach under your shoulder blades at their inner rims.  They draw your shoulder blades away from each other and lock them there, helping with stability and mobility. They work with your rhomboids to keep shoulders stable, one kicking in when your arms are being pulled forward and the other taking over when your arms are being pushed back. For example, when you hold weights out in front of you, your rhomboids engage to keep your shoulder blades from flying apart. When you’re pushing against something (the floor), your serratus anterior takes over to keep your shoulder blades from collapsing inwards. Finally, when you want to keep your shoulder blades down, the two muscles join forces. They play a major role in your basic ability to raise your arms above shoulder height. When you want to raise your arms, your serratus anteriors on each side tilt your shoulder blades upwards at their outer edges. This maneuver effectively points your shoulder joints more upwards so that your arms can move around freely at a higher range. 

  • When these are weak: They contribute to neck problems, rotator cuff issues, numbness down the arm, poor circulation, and lymphatic return through the armpits. Serratus anterior reminds us to use muscles that we can’t see, and to focus on connecting and feeling.
  • Exercises to strengthen them: Push ups, chest presses, planks, oblique reaches and twists
  • Benefits of working them:
    • Strong serratus anteriors prevent unstable winging of the shoulder, and aids in opening the chest and liftting your posture. 
    • These muscles protect against neck pain by enabling your arms to move in a large range without compressing your neck.

The Pectoralis Minor is a fan-shaped muscle and the smallest of the two chest muscles. It’s located from the third to fifth ribs under the pec major and inserts into the scapula. It works with Serratus anterior to pull the scapula forward and down, and pulls the ribs up which assists with inhales. 

  • Exercises to strengthen them: Chest press, push-ups, chest flies, chest press, etc. 
  • When weak: If your pectoralis minor becomes short due to a rounded shoulder posture, improper breathing or muscular imbalances, it can feel tight and eventually cause painful shoulder impingement and winging of the scapula. As strange as it may sound, a poorly developed or tight pectoralis minor can also affect your gait by causing disfunction in the hip flexor, and inhibiting swinging of your arms as you move. Your pectoralis minor can also play a role in back pain.  
  • Benefits of working them:
    • A strong pec minor helps with posture, helps to develop a balanced and proportional body and assists with lifting (kids, groceries, etc.). 
    • When working your pec minor you’re also activating supporting muscles in the shoulder, triceps, and back, which is an added bonus.

Levator Scapula lifts (elevates) the shoulder blade and is located along the lateral posterior sides of the neck. It, with the rhomboids, forms the deep layer of shoulder muscles. It helps to elevate the shoulder, rotates your neck and bends it to the same side (ear to shoulder), and help bend the neck backwards or stabilize it when you look down. 

  • Exercises to strengthen them: Holds up neck during Superman in core, helps hold up neck and have good posture during leg work
  • When weak: Over or under use can cause this and causes pain, inflammation, tension and restrictive neck movement. It can also cause trigger point pain in other points of your neck and shoulder.
  • Benefits of working them:
    • Helps with a taller and “prettier” posture
    • Alleviates neck and back pain

The upper and mid Trapezius lift the shoulder girdle (happens when people shrug shoulders up by ears), while the Lower Trapezius depresses the shoulder girdle. When the left and right sides are paired, they form a trapezium, and they are superficial layers of muscle on the back only partly covered by the large latissimus dorsi muscle. 

  • Exercises to strengthen them: Upright row, reverse fly, shoulder press
  • When weak: The most common cause of tight or weak traps is STRESS, which causes headaches, stiff neck and pain. Pressing shoulders down your back and away from your ears helps relax these muscles. 
  • Benefits of working them:
    • Injury prevention – secure the neck during contact
    • Stabilize the shoulder

The rhomboids (major and minor) retract the scapula (shoulder blade) and stabilize the shoulder girdle. Rhomboid major is larger and positioned below rhomboid minor. 

  • Exercises to strengthen them: any kind of row, rhomboid press/squeeze, wide negative push ups
  • When weak: You will hunch your back and round your shoulders, causing all sorts of neck, shoulder and back pain. 
  • Benefits of working them:
    • Prevent hunched back and help with posture

Shoulder Girdle:

Serratus Anterior Info: 

Pec Minor info:

Levator scap info:

Traps info:

Rhomboids:

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