Should my mother more strict, or am I being unreasonable?

I think my family's dynamics need re-adjustment. My 14 y/o brother is entitled, occasionally violent and very disrespectful of everyone in our household, especially our mom. When he doesnt get his way or sees that I get different freedoms than he does (I'm three years older and have different restrictions/freedom:ei. my mother treats me more like an adult than him), he raises his voice and 2/3 times, he physically pushes her around. My relationship is also complicated. Due to my father's psychological and previous physical abuse, I don't have any relationship with him even though we live together (I have panic attacks in situations I even accidentally have to talk to/be around him) My brother uses this as a threat(he threatens to call him down). Of course, I make it appear as I just brush it off, and I do my best to ignore his antics. He disrespects me by calling me a *****/other names, messing with my stuff ect. I also have a dog (a gift. I've always been finacially and otherwise responsible for) , that dislikes him (though my brother adores her). He gets to me by bothering her, screaming at her and feeding her (only mom and I are allowed to feed her at all--her digestion is very sensitive). When I've had enough, I let him know, and get my mum to 'stop him'. She only tells him off, and he whines and ignores her. Sometimes he pushes her around when he is told 'no'. She is usually unable to get him to stop at all. Should my mom be more responsible for him?