Maria de Villota underwent further surgery at Addenbrooke's Hospital in Cambridge on Friday following her accident earlier this week while conducting a straight-line aero test with the Marussia F1 team at Duxford.
Surgeons were said to be 'sufficiently happy with her progress to allow the operation to go ahead'.
Marussia added that the 'next phase of surgery' was completed 'successfully' and that her condition has further improved to the extent that she is now 'serious but stable'.
The full statement from Marussia F1 read:
“Earlier today, Maria underwent further surgery at Addenbrooke's Hospital in Cambridge. This was a planned procedure that would depend upon the continued stability of Maria's head injuries, and this morning the medical team were sufficiently happy with her progress to allow the operation to go ahead.
“The surgeons successfully completed the next phase of surgery required to address Maria's facial injuries. After the lengthy initial procedure, which commenced on Tuesday and concluded on Wednesday, today's secondary operation took significantly less time.
“Since the operation today, Maria's condition in relation to the head trauma she received has further improved, to the extent that she is now 'serious but stable'.
“Whilst Maria remains acutely ill, this confirms that she has been responding well to the treatment she has received since her accident. Coupled with the significant progress that has been made with regard to her facial injuries, we feel sufficiently comfortable to proceed with a further update.
“On a more personal note, we have taken a great deal of encouragement from today's developments and the rather more positive signs for Maria's family.”