The pronator quadratus and the pronator teres are either reduced or absent.
In the name-typical form "quadratus" the forewing has a yellowish white spot before the second median.
Between the anterior and middle layer lies the quadratus lumborum muscle.
Laterally, it blends with the anterior layer at the lateral border of quadratus lumborum.
It is assisted in this action by pronator quadratus.
It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, and passes obliquely across the quadratus lumborum and iliacus.
It forms an arch over the quadratus lumborum muscle.
In the forearm, this action is performed by pronator quadratus and pronator teres muscle.
