Kirk Leatherland climbed up alongside the 79-year-old during an argument at their Willenhall home and bit her on the nose and cheek as she frantically pressed her emergency assistance alarm, a judge heard.
Then he pulled out her false teeth and threw them across the bedroom so hard that they broke, Wolverhampton Crown Court was told.
“He remembers putting his fist into her mouth and thumb into her neck,” said Mr Andrew Wallace, prosecuting.
Leatherland also admitted repeatedly punching his mother, grabbing her round the throat and biting her arm, the court heard.
Mr Wallace added: “His mother was lying prone in bed absolutely at his mercy. There was nothing she could do to protect herself.
"She had black eyes, cuts around the eyes, cut lips and mouth.”
The prosecutor concluded: “This was not one blow it was sustained. It is difficult to imagine anybody more vulnerable than a bed ridden, frail elderly person.”
The 49-year-old alcoholic admitted drinking a bottle of vodka and smoking cannabis before launching the attack.
He was arrested when police and St John Ambulance staff arrived in response to the emergency alarm at Bowker Street, Portobello, where he shared a house with his mother who has been moved to a nursing home since the incident in July last year.
Mr Justin Hugheston-Roberts, defending, said: “He had no explanation and said: “I am just so very ashamed.”
The defendant pleaded guilty to causing grievous bodily harm and was jailed by Judge Sarah Buckingham who told him: “You behaved in an abominable way with extreme violence.”