Surgeons claim Michelangelo painting of God contains diagram of the brain that was a hidden dig at the Vatican

A Dan Brown-style Da Vinci Code mystery has emerged from within a Michelangelo fresco painted in the Vatican's Sistine Chapel.

Brown's blockbuster book described a hidden message in Leonardo Da Vinci's Last Supper that suggested Christ had married Mary Magdalene, causing fury at the Vatican.

Now two neurosurgeons have claimed to have uncovered a 500-year-old mystery involving his Renaissance rival Michelangelo - in which he painted a brain inside a painting of God to hide it from then Pope Julius II.

Subtle: From a distance, the diagram that the two surgeons claim is a brain cannot be seen above the vertical line in God's robe that they say is meant to represent the spinal column

God's neck is painted to appear as the human brain when viewed closely, with the verical line in his robe representing the spinal column

Writing in the scientific journal Neurosurgery, Ian Suk and Rafael Tamargo of the Johns Hopkins University School of Medicine in Baltimore, Maryland, claim Michelangelo painted a brain within an image of God.

In the fresco The Separation of Light from Darkness, Suk and Tamargo say that leading up the centre of God's chest and forming his throat, there is a precise depiction of the human spinal cord and brain stem.

Art critics and historians have often questioned the strange anatomical irregularities in Michelangelo's depiction of God's neck in the panel and the uneven lighting in the area as well.

The figures in the fresco are illuminated diagonally from the lower left, but God's neck, highlighted as if in a spotlight, is illuminated straight-on and slightly from the right.  Some have suggested it is a mistake but Suk and Tamargo are convinced it is a hidden message as in no other figures did Michelangelo make such a serious error.

In their paper they write: 'Did Michelangelo, at the peak of his abilities, intend to portray something else? We submit that he did.'

They claim by superimposing a detail of God's odd 'lumpy neck' in the Separation of Light and Darkness onto a photograph of the human brain, the lines of God's neck trace precisely the features of the human brain.

Also unusual, they say, is the roll of material that rises up the centre of God's robe in an unnatural manner. The clothing is bunched up and the fold clashes with what would be the natural drape of fabric over God's torso and they insist it is the human spinal cord, ascending to the brain stem in God's neck.

They conclude by saying: 'Being a painter of genius, a master anatomist, and a deeply religious man, Michelangelo cleverly enhanced his depiction of God in the... panels on the Sistine Chapel vault with concealed images of the brain and in this way celebrated not only the glory of God, but also that of His most magnificent creation.'

Michelangelo was well known as a painter, sculptor and inventor but he kept his interest in anatomy secret for fear of punishment from Pope Julius and he even destroyed sketches and notes for fear of being discovered.

While working on the Sistine Chapel at the Vatican, Michelangelo had several rows with Pope Julius II and even depicted himself in two self portraits in the frescoes as being tortured. After Michelangelo died a subsequent Pope, Paul IV, ordered fig leaves to be put over nudes in the work because he felt they were an insult.