True about anterior intercostal aery are all except?

Aerial supply of chest wallEach of upper nine intercostal spaces (1 to 9) have one posterior and two anterior intercostal aeries. The 10th and 116 spaces have one posterior intercostal aery (no anterior intercostal aery)Posterior intercostal aery is the main aery of intercostal space and runs in the costal groove along the upper border of an intercostal space, lying between posterior intercostal vein and intercostal nerve (relationship from above downward VAN). 1 st and 2nd posterior intercostal aeries are branches of superior intercostal aery (a branch of costocervical trunk from 2"d pa of subclan aery). Lower nine (3th to 11th) posterior intercostal aeries are branches of descending thoracic aoa. Right posterior intercostal aeries are longer than the left.Anterior intercostal aeries for upper six spaces (two in each space) arise from internal thoracic or internal mammary aery. For 7th to 9th spaces, these are branches of musculophrenic aery (terminal branch of internal thoracic aery).