ST. CLOUD (AP) — A St. Cloud woman who pleaded guilty to seriously injuring her infant son has been sentenced to more than seven years in prison.

Crystal Lee Tjernagel pleaded guilty to third-degree assault and malicious punishment of a child. The 27-year-old was sentenced Friday.

Her 6-month-old was hospitalized in September with seizures. Doctors said the boy had bleeding around his brain that was consistent with child abuse.

Tjernagel told investigators she'd been bouncing the boy roughly on her knee. She said their heads collided and the boy grew quiet, eventually growing limp.

She later acknowledged to police that she may have shaken the boy.

She was sentenced to 7.5 years in prison.

A telephone number for her attorney couldn't immediately be found Saturday.

Copyright 2011 The Associated Press.