just broke the exclusive news that Caterina Scorsone, who plays the recurring role of Dr. Amelia Shepherd on Private Practice, has been promoted to series regular. Amelia is the younger sister of Grey’s Anatomy’s McDreamy and is a neurosurgeon just like her older brother. Scorsone even went to medical school in real life before deciding she preferred to play one on TV, but as a viewer I appreciate that she actually knows her stuff.

Amelia appeared in the last 5 episodes of season 3 of the Grey’s spin-off. In April, I reported that she debuted in the episode “Eyes Wide Open,” where she was part of a team brought in to help Kayla, the surrogate coma patient carrying three babies. Her presence really rattled Derek’s ex-wife Addison, though they had to work together to save the patient and Amelia stayed on temporarily to consult for Oceanside Wellness.

Series creator Shonda Rhimes has revealed they are certainly planning a Shepherd-centric crossover for this upcoming season focusing on Amelia and Derek. How excited are we to finally see McDreamy interact with one of his much-talked-about sisters, especially one that followed in her brother’s footsteps career-wise?

Joining Scorsone as a series regular for season 4 is Brian Benben’s character Sheldon Wallace, who had a recurring role for the past 2 seasons as a Psychiatrist from rival practice Pacific Wellcare and was Violet’s lover/possible baby daddy recently turned Charlotte’s new love interest.

The fourth season of Private Practice will premiere on Thursday September 23, 2010 in it’s normal time-slot at 10pm following Grey’s Anatomy. The season premiere will pick up a few weeks from where we left off, giving everybody some time to grieve after Dell’s tragic death.