Which membrane is in the way if you try to reach the lesser peritoneal sac and head of the pancreas after penetrating the greater peritoneal sac?

Gastrohepatic ligament The gastrohepatic ligament is the pa of the lesser omentum that separates the greater peritoneal sac from the right poion of the lesser peritoneal sac. This poion of the lesser omentum has no significant blood vessels within it and may be incised for surgical access. Ref ganong's review of medical physiology 25e p679