A man beaten by an off-duty firefighter last year suffered injuries similar to a car accident victim, a prosecutor said Monday.

Speaking to a jury during her opening statement, Deputy District Attorney Kristy Imel said Jory Brigham had 17 fractures in his face after an altercation with firefighter John Ryan Mason at a San Luis Obispo bar.

“This case is about rage, opportunity and revenge,” Imel said, holding a photo of Brigham’s badly battered face.

But an attorney for the firefighter countered that his client was merely defending himself against an aggressor who had been drinking all day.

“Alcohol is critical in this case,” Chris Casciola said in his opening statement. “We all know what it does to a person — liquid courage or forgetfulness.”

Mason, 35, a firefighter with the San Luis Obispo City Fire Department, faces charges of felony assault with great bodily injury and battery with serious bodily injury.

According to court testimony, he and Brigham mostly knew each other through their wives, who were longtime friends. When Mason was having marital problems with his wife, Brigham posted a comment on his Facebook page that upset Mason. It read, “It’s amazing how socially acceptable it is to walk out on your family.”

Mason responded with a comment: “You are so bored with your life that you have to meddle with others. Mind your own (expletive) business.”

The two met twice after that. Brigham said he was trying to smooth things over each time. Casciola said Brigham was dogging his client, even after Mason reconciled with his wife.

“Jory Brigham won’t let it go,” he said. “And he won’t stop talking about it.”

On June 4, 2011, the two attended a wedding for a mutual friend.

Later that night, they were both at Pappy McGregor’s Bar & Grill in San Luis Obispo when they wound up in the establishment’s restroom. There, Brigham testified Monday, Mason made a derogatory comment, to which Brigham responded, “Is this the way it’s going to be? Our wives are best friends.”

An argument ensued, he said, with Mason telling him to mind his own business. At one point, Brigham testified, Mason raised a fist and told him he was going to beat him up.

“I remember waking up on the floor of the bathroom,” Brigham said.

After the altercation, Mason left the building with his wife, and paramedics took Brigham to a hospital. The bloodied Brigham suffered a broken nose, jaw and cheekbones. After a seven-hour surgery, the Los Osos furniture builder said, his jaw was wired shut for five weeks, and to this day, he said, he has nasal problems, numbness in his face, and teeth and ear aches.

Casciola, who will cross-examine Brigham today, told jurors that witnesses saw Brigham as the aggressor — and that Mason stopped striking as soon as he knew Brigham would not fight back.

“Now we can get it straight,” he said, noting that his client has been waiting to have his side heard, “because Jory Brigham went into that bathroom after Ryan Mason.”

After portraying Brigham as a gossip-hungry, intoxicated aggressor, Casciola said Brigham had another motive to portray himself as a victim: He has hired an attorney to sue Mason.

“So Jory Brigham has some real interest in how this case turns out,” he said.