I think I have tight muscles over ribs after breast augmentation. Is this my pectoral muscle? (Photo)

Judging from your photos you have "cording".  This is often related to inflammation in a vein or lymphatic vessel.  It will usually respond well to massage, anti-inflammatory medications and occasionally cortisone injection.I suggest consulting a physiotherapist with an interest in breast surgery.  They are experts are managing this sort of condition and should help it to resolve more quickly.Kind regards,Dean 

This is not a muscle at all.  It is a coagulated vein that sometimes occurs after breast augmentation called Mondor's cord. There is nothing dangerous about it.  I can be treated with aspirin, warm compressed and massage.  The vein, which no longer has blood flowing through it, is now just a scar.  The scar is only a problem because it causes constriction.  I massage the scar out to break it into small segments of scar so that it no longer is painful and constricting.

This cord is an inflamed vein.  Non steroidal and warm compresses over the sensation chest and not the the numb breasts will help it resolve more quickly.

I agree that your symptoms and photos are consistent with development of a Mondor's cord. It's a clotted vein that has scarred and causes discomfort. I recommend massaging the area to break up the the scar and soften it. 

From your photos, I believe what you are experiencing is superficial thrombophlebitis of a subcutaneous vein (Mondor's disease).  This problem is not uncommon after breast augmentation, is self limited, and usually resolves in a few weeks.  Anti-inflammatory medications, gentle massage and local heat can speed its resolution.  Check with your surgeon for their recommendations.