Pectoralis Minor…Part 13 of the grumbly muscle blog…

What on earth is a pectoralis minor?

As part of the name would suggest, its one of the pectoral muscles in your chest, in fact you’ve got more than one. There is Pectoralis Major (Pec Major), the larger more superficial chest muscle that people are so fond of training in the gym and then there’s ‘lil’ old Pec Minor, which most people haven’t heard of.

What does a Pec Minor do? Well…for such a small muscle, it has a lot of effect on the scapula.

  • It helps 1) stabilise the scapula (along with middle fibres of traps), 2) depress (with help from lower traps and serratus anterior), 3) protract (with serratus anterior), 4) internally rotate and 5) downwardly rotate (with levator scapula and rhomboid major and minor).
  • It elevates the ribs and can help with inspiration (of breath).
  • Pec Major, Minor and serratus anterior work together to provide a wide range of movement of the scapula.

 Anatomy

It sits quietly underneath Pec Major. The muscle originates from the 3rd-5th ribs and inserts just under the outside of the clavicle on the coracoid process. The coracoid process is part of the scapula.

Why does it get grumbly and what happens when it does?

It can become weak, but more importantly, * it can become often shortened*, and a ‘rounded shoulder posture’ can help make this a reality, so too can problems in the shoulder joint and poor breathing.

As I’ve discussed in other blogs, if serratus anterior is weak, pec minor ‘takes over’ and the scapula ‘wings’.

Tightness and shortness of this muscle can also be the cause of thoracic outlet syndrome by decreasing the space in which nerves and blood vessels occupy between the first rib and the coracoid process (where Pec Minor inserts). This leads to either neural symptoms; pins and needles, numbness, burning, tingling or sharp shooting pains, vascular symptoms (constricted blood flow to the hand and arms) or both.

It will also restrict movement of the shoulder joint by constricting the scapula’s ability to move.

Trigger points (hypersensitive areas of muscle) in this muscle cause pain in the front of the shoulder, the inside of the arm, palm, middle, ring and little finger.

What can we do about it?

We can stretch it off regularly and we can perform soft tissue releases on it. As its not a superficial muscle and the pec major muscle is quite large, massage is less effective.

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