The muscle is in the union of the regions thoracic and lumbar. It arises from the T11 vertebrae and it works through superolateral L2 to be inserted in the inferior edge from the 9 to the 12 of the ribs.
It is located in the confluence of the regions thoracic and lumbar: it is of a quadrilateral form irregular, ampler than the later muscle serratus superior, and separated of her by an ample interval.
Thoracic or three lumbar vertebrae is originated by a thin aponeurosis of superior the thorny supraspinal ligament and two and two apophyses inferior.
When happening oblique upwards and lateralward, one becomes fleshy, and a little beyond their angles is divided in four digitaciones flat, that are inserted in the inferior edges of the four inferior ribs.
The thin aponeurosis of origin intimately is mixed with fascia lumbodorsa, and the aponeurosis of the wide dorsal muscle.