The PCL is an intracapsular ligament along with the anterior cruciate ligament (ACL) because it lies deep within the knee joint.They are both isolated from the fluid-filled synovial cavity, with the synovial membrane wrapped around them. The PCL gets its name by attaching to the posterior portion of the tibia.he PCL is an intracapsular ligament along with the anterior cruciate ligament (ACL) because it lies deep within the knee joint. They are both isolated from the fluid-filled synovial cavity, with the synovial membrane wrapped around them.