The two females on either side of the central figure represent the two women in Picasso's life in 1934. In the context of the Crucifixion theme, they are characterized as the two thieves either side of Christ.
The female on the left, is Marie-Thérèse Walter in a pose almost identical to that of the Magdalene in a numerous acclaimed Renaissance Crucifixions, including the great Mond Altarpiece by Raphael.
Picasso was a strict traditionalist, despite his amazing ability for innovation and revolution.
The central figure has one clearly visible outstretched arm, to the left. Another outstretched arm, determining the Crucifixion pose, is concealed in the island of light in the right hand figure's face. This 'flying arm' is a recurrant feature in Picasso's graphics and poems of the 1930's. In "The Unknown Masterpiece," the arm is severed and the end of the stump doubles as the black circle on the right. Severed arms such as this are a mysterious symbolic element in many of Picasso's works, including Guernica.
The spiral light source in the upper left corner and the large black semi circle in the upper right corner, represenet the Sun and Moon traditionally seen in Renaissance Crucifixions. They represent duality and complimentary opposites of life and death and so on. It is also a common underlying theme of Picasso's work in the '20's and '30's.
The ladder, or pair of steps, on which Picasso stands crucified is another traditional Crucifixion motif. It also symbolizes the alchemical ladder or the stages of initiation.
The black almond shaped area In Picasso's abdomen represents the gaping wound in Christ's side, always present in traditional Crucifixions. Out of the wound, appears an enormous flow of blood, represented by the vertical black column of ink between the central and right hand figures. Picasso was known to have made the analogy between his own blood and the ink in his drawings, on more than one occasion.
Rising out of the left hand figure's shoulder, there is a Tau Cross, associated with the Mithraic cult and with alchemy. Behind the female on the right there are some crossed pen lines indicating another Cross. These two crosses reinforce the idea that the two women in the drawing are also undergoing crucifixion.
Either side of the ladder are the shadowy forms of two dark angels, which again are traditional Renaissance crucifixion motifs.
The central figure's thrown back head suggests he is at the moment of death or in a state of transfiguration, analogous to death.
Below his torso, concealed within the wash, there is a half skull whose eye is the black oblong in the center of the composition. The skull is yet another crucifixion motif and one of Picasso's most important symbols.
"The Unknown Masterpiece," contains a number of other references to crucifixion which are linked to the stories of Parsifal, Oedipus, Odin and Frankenstein.