@MontereyJack,
This medical expert is an excellent and experienced witness. She knows defense attorney's maneuvers, and she's not falling into them. She's not giving O'Mara an inch.
And just watching O'Mara, it's clear defense lawyers have no interest in the truth, they may actively try to distort or obsure the truth--for them, it's really a matter of getting their client off, by hook or by crook.
Her testimony is very damaging to Zimmerman's credibility regarding any realistic fears his life was in danger because of being beaten or having his head pounded on the pavement. She's saying there was no medical evidence of head pounding or of having been pummeled in his face and body.