The condition of actor and comic Tracy Morgan, best known for TV's 30 Rock and Saturday Day Night Live, is improving nearly a week after sustaining serious injuries in a New Jersey highway crash that killed one of his friends.

Though the 45-year-old Morgan is still hospitalized in New Brunswick, N.J. — in critical but stable condition — "he continues to show signs of improvement," according to his spokesman, Lewis Kay.

"His medical team remains optimistic that his recovery is progressing."

His injuries included a broken leg, nose and ribs.

Morgan's fiancée, Megan Wollover, is also by his side, Kay added.

Weekend crash on N.J. Turnpike

Early last Saturday, Morgan, his assistant and other comedians in a limousine van were involved in a six-vehicle, chain-reaction crash on the New Jersey Turnpike with a Wal-Mart delivery truck.

Tracy Morgan Accident

Wal-Mart truck driver Kevin Roper has pleaded not guilty to charges of vehicular manslaughter and assault by auto. (New Jersey State Police/Associated Press)

Comedian James "Jimmy Mack" McNair was killed in the accident, while Morgan and others were injured.

On Wednesday, truck driver Kevin Roper appeared in court and pleaded not guilty to charges of vehicular manslaughter and assault by auto.

A criminal complaint alleges that he had not slept in more than 24 hours before the crash, during which he swerved to avoid slowed traffic and plowed into the limousine van.

Wal-Mart Stores Inc. has not shared details of Roper's driving route, but has said it believes he was complying with federal safety regulations. The company has also pledged to cooperate with state and federal investigation of the crash.

Roper is free on $50,000 bail.

With files from The Associated Press and Reuters