Doesn't articulate with the inferior demifacet of the superior vertebra. The lower joints are strengthened anteriorly and posteriorly by radiate sternocostal ligaments. No movement normally occurs at these joints. A lactiferous sinus , just deep to the areola, allows accumulation of milk during lactation. Drains the rest.
Inferior muscles are continuous with the internal oblique of the abdomen.
Same direction as internal intercostals.