That's the crux of confusion for many to this day-extensions behind the head or seated are both excellent, the best thing out there for the long head which is the largest part of the triceps and the best potential area for adding size. Skulls are often confused with lying extensions and aren't in the same league whatsoever in terms of effectiveness.
There are also some big downsides to skulls - greater pressure on the elbows and connective tissues rather than on the muscle, and if you're serious and trying to work to failure, a fair chance that last tough rep's gonna land the bar on your face when you're weakest.
Skulls are not a serious exercise relative to other options such as seated ext. with back braced, lying or cable extensions.
French press is another confusing name, that in various places are defined as either extensions or skulls, and seated or lying. Just a lot of confusion-use extensions in workouts and as the best more accurate and least confusing name.
You said it, brother.
Conventional skulls
(bar to head) used to make my elbows “scream,” and I’m convinced they were a major player in what caused a lot of my Olecranon/epicondyle problems.
I know that you, Meso78, JPM, SF/QO, and I have all had more than a few discussions at times regarding the effectiveness and other finer details of BTH extensions – from Scott variations to bodyweight extensions/tiger dips, etc.
I used to load up the Hammer dip machine and get someone to help me start that first rep.
And I used to grab the dipping belt and hang db’s and plates from the chain that always unceremoniously rattled my nuts as I climbed up to the dipping bars.
But it wasn’t until I focused almost exclusively on extension work that my tri’s started to develop something resembling a downward sweep – that “reverse peak” opposite the biceps during a front double bi pose.
Granted I still have a very long way to go, but at least the backside of my arm is no longer flat.