Othello is appointed general in the Venetian Army. His conniving, jealous officer Iago tricks him into believing that his wife Desdemona is having an affair with his Lieutenant so that he’ll go mad. The seeds of doubt, anger, obsession, hatred and violence are indeed well planted in Othello’s head, causing him to murder his wife.
Othello’s head is sprouting seeds of hatred towards his wife and surroundings. Those roots are symbolized as nails and screws, slowly protruding out and torturing his mind into madness.