Victory over Real Madrid at the weekend saw Barcelona move top on the head-to-head record, and they have now moved three points clear of Los Blancos following a thumping victory over the division's basement side, who went to pieces in the second 45 minutes after initially getting back into the game.
As for Osasuna, Raoul Loe, Miguel Flano and Didier Digard were among those to remain on the sidelines, meaning that the visitors were far from full strength at Camp Nou. Pedro Leon, who entered the match having scored 10 times and provided five assists in 33 La Liga appearances this season, led the line with support from Jaime Moreno.
After a slow start, Barcelona made the breakthrough in the 12th minute of action when Messi took advantage of a poor back-pass from Antonio Fausto before chipping the onrushing Salvatore Sirigu to send the home side into a 1-0 lead.
Osasuna barely managed to break out of their own half in the opening 25 minutes as Barcelona continued to dominate possession, although clear chances were few and far between in a first period which was almost too easy for the hosts.
Messi came close to scoring a second for Enrique's side in the 27th minute after a smart touch from Paco Alcacer found the Argentine inside the Osasuna box, but his half-volley was high of Sirigu's crossbar.
The Spanish champions did double their lead in the 30th minute, however, when under-pressure midfielder Gomes found the bottom corner with a well-placed finish after meeting a smart cross from Ivan Rakitic.
Turan should have scored a third for Barcelona in the latter stages of the first period, but the Turkish international headed a Mascherano cross wide of the post after breaking free of the Osasuna defence, before Alcacer brought a smart save from Sirigu with a flying header.
Osasuna scored in the 48th minute with their first shot on target, however, as a brilliant free kick from Roberto Torres ended up in the top corner and Camp Nou was stunned into silence.
Barcelona came close to restoring their two-goal advantage in the 50th minute when Mascherano leapt highest inside the Osasuna box before sending a corner towards the bottom corner, but Sirigu made a super save onto the post.
Osasuna continued to threaten on the counter-attack, however, and Marc-Andre ter Stegen made a smart save to keep out another strike from Torres as Barcelona rode their luck at the back once again.
The home side scored their third of the match in the 57th minute though when Portuguese midfielder Gomes swept the ball home from close range after Gerard Pique had hit the post with a clever effort.
Three then became four in the 61st minute when Messi drove at the heart of the Osasuna defence before curling an effort into the far corner, before Alcacer made it 5-1 in the 64th minute after chipping the ball over isolated goalkeeper Sirigu from close range.
It went from bad to worse for Osasuna in the 67th minute when Fran Merida sent Denis Suarez tumbling inside the away side's box, and it was Mascherano that stepped forward to score his first Barcelona goal from the penalty spot.
The home side appeared to have mercy on Osasuna in the final 20 minutes of action, with the pace of the contest dropping as both teams switched their attention to more pressing matters. There was time for more more goal, however, as Alcacer netted his second in the 86th minute to make it seven on the night.
Next up for Barcelona is a trip to Catalan rivals Espanyol on Saturday night, while Osasuna's seemingly losing battle against the drop will continue at home to Deportivo La Coruna on Sunday afternoon.