Though the wings that protected the altarpiece's frontispiece were lost some time ago, those belonging to the main altarpiece have been conserved. For many years, they were of more interest to researchers than the carved altarpiece itself.
The original paintings have been attributed to Quentin Matsys, though they have been more recently attributed to one of his disciples by the name of Maestro Morrison of the Triptych. On their interiors, the left wing displays the painting of the Adoration of the Shepherds and the Epiphany on the right, while the exterior surface is illustrated with the Mass of St. Gregory. (San Gregorio).
The wooden panels on the plinth are the work of a disciple of Alonso Berruguete and they reproduce the busts of St. Dominic (Santo Domingo), St. Luke (San Lucas), St. Marcos (San Marcos) and St. Francis (San Francisco) on the outer side and St. Jerome (San Jerónimo) and St. Augustine (San Agustín) together with the busts of the founders on the inner.