Soft Tissue Release: Pec Minor & Subclavius

Download the PDF guide from the resources section below.

What this lesson covers

• The anatomy and clinical role of the pec minor and subclavius in costoclavicular compression
• Self-massage technique for the pec minor — standing or prone
• Self-massage technique for the subclavius — below the clavicle
• How often to perform this release and how it fits into the daily session

Equipment needed

• Lacrosse ball or firm massage ball
• Tennis ball (acceptable substitute)

Why these two muscles

The pec minor attaches from ribs 3–5 to the coracoid process of the scapula. When tight, it pulls the shoulder blade into anterior tilt and protraction — narrowing the subcoracoid space and compressing the neurovascular bundle.

The subclavius runs horizontally just below the clavicle, from the first rib to the underside of the collarbone. Restriction here directly narrows the costoclavicular space — one of the three primary outlet compression points.

Both muscles respond well to sustained manual pressure. The goal is not to aggressively dig — it is to provide a sustained input that reduces tone through the golgi tendon reflex and improves local circulation in tissue that has been chronically compressed.

Pectoralis minor: the most underappreciated TOS driver

The pec minor is a small, triangular muscle that runs from the coracoid process of the scapula down to the 3rd, 4th, and 5th ribs anteriorly. Its primary function is to depress, protract, and anteriorly tilt the scapula. When functioning normally, it contributes to controlled scapular movement during arm elevation.

When chronically shortened — as it is in virtually every desk worker, driver, and sustained-flexed-posture individual — it creates three simultaneous problems for the thoracic outlet.

First, it holds the scapula in anterior tilt and downward rotation. This prevents the upward rotation that is required to keep the outlet open as the arm elevates. The subcoracoid space — the passage beneath the pec minor itself — narrows under load.

Second, the anteriorly tilted scapula draws the coracoid process forward and down. This rotates the clavicle, narrowing the costoclavicular space where the subclavian vessels and brachial plexus pass.

Third, the protracted shoulder position closes the anterior chest and contributes to the forward head posture pattern that loads the scalenes. It is a downstream driver of the upstream compression that Phase 1 was addressing.

This is why pec minor release is not optional maintenance work in Phase 2. It is directly addressing one of the primary structural drivers of outlet compression.

Subclavius: the overlooked costoclavicular compressor

The subclavius sits beneath the clavicle, running from the first rib and its cartilage up to the underside of the clavicle. Its function is to depress the clavicle, stabilize the sternoclavicular joint, and protect the subclavian vessels beneath it.

When the subclavius is hypertonic, it pulls the clavicle downward, narrowing the costoclavicular space from above. This is the mechanical opposite of first rib elevation — both compress the same space from different directions. In many TOS patients, both are happening simultaneously.

Subclavius tightness is less commonly addressed in general shoulder rehabilitation, which is part of why TOS patients can go through multiple rounds of physical therapy without meaningful improvement. Treating only the scalenes and leaving the subclavius unaddressed is like reducing compression from one side while the other side remains tight.

How the releases work

Pec Minor Release — Ball or Thumb Pressure

Target the pec minor at its insertion on the coracoid process (just below and medial to the front of the shoulder) and along its belly running toward the ribs. Place a ball against the anterior chest just below the collarbone, lateral to the sternum. Sustained pressure at 3-4/10 with slow deep breaths. The exhale creates relative movement between the rib and the ball, adding a dynamic component to the release. 60-90 seconds per side.

Subclavius Release — Fingertip Pressure Under Clavicle

Use two fingertips to apply gentle upward pressure into the soft tissue just beneath the clavicle, moving from the sternoclavicular joint laterally toward the shoulder. This area is sensitive — pressure at 2-3/10 only. Sustained holds of 20-30 seconds at each point rather than sliding. Combine with slow exhalation. The goal is not aggressive tissue work but rather sustained inhibitory input to reduce motor tone in the subclavius.

What to expect

The anterior chest and subcoracoid region is often more sensitive than the lateral neck in TOS patients because it has been chronically compressed and is closer to multiple nerve branches. Start with lighter pressure than feels necessary. Many patients find that after 3-5 sessions the area becomes significantly less tender as tissue tone decreases.

A common experience is a sense of the shoulder dropping slightly and the chest opening after release — this is the scapula moving into better posterior tilt as the anterior restriction decreases. That is the mechanical change you are looking for.

Key technique reminders

• Pressure: 2 to 3 out of 10. Sustained compression, not aggressive digging.
• Breathing: Slow, diaphragmatic breaths while holding pressure. The exhale naturally deepens the release.
• Duration: 60 to 90 seconds per area. Move slightly and repeat.
• Stop if: You feel numbness or tingling radiating down the arm. That means the pressure is too deep or too medial. Reposition immediately.

Do this release before every session in Phase 2 — before your mobility work and before your activation work. It primes the tissue for everything that follows.

A note on the ‘pull your shoulders back’ instruction

Many TOS patients have been told repeatedly to pull their shoulders back. With a tight pec minor, this instruction creates a problem: the scapula can only retract by being pulled posteriorly against the resistance of the pec minor. The result is a forced, effortful posture that the patient cannot sustain, and that often increases anterior chest tension rather than reducing it.

Releasing the pec minor first allows the scapula to sit in a more posterior position passively — without effort. The shoulder comes back not because it is being held there but because the tissue restriction preventing it has been removed. This is the difference between correcting a posture and restoring a tissue.

Up next:

Lesson 3 — Phase 2 ROM protocol.