BOSTON — The trauma surgery chief at Boston Medical Center says most of the injuries his hospital treated after the marathon bombings were to the lower extremities.Dr. Peter Burke says the hospital treated 23 people following the blasts, and 19 remained there on Wednesday morning. He says two patients, including a 5-year-old child, remain critical, but says all the patients are making progress and are expected to survive.Dozens of others have been released from hospitals around Boston.