The topic of “Neck Strikes” seems to of been very popular of late (at least with the individual's that I've been conversing with). I believe a lot of the confusion, has to do with understanding how many different “types” of these strikes that there actually are.
First and foremost, the neck (itself) isn't really all that large. Yet, there are a fair number of different locations to strike it upon (and there are just as many different methods as well as directions to perform those strikes from).
The initial neck strikes that we teach to students are performed with the student's forearm (a large implement, utilized upon an equally large/general area). Unfortunately, this can lead to a student (mistakenly) attempting to use that implement with (excessive) force (as is often observed in the numerous “U-Tube” videos that are out there).
There are additionally, a fair number of focused (types of) strikes that are available as well. These can utilize the (or more often “a”) finger-tip, or the back of the tori's hand (similar to a “Back-Handed Slap”).
Beginning students are commonly shown several different manners of these types of strikes for varying positional situations. These will often include strikes that are implemented using a finger " joint" (knuckle) as well as the finger-tip(s).
When strikes are utilized (upon the neck), they tend to be used in an angular manner. Even when a finger thrust is utilized upon the sternal "notch" (in the center of the body at the top of the sternum, at the base of the throat region), that strike is directed downward, not towards the rear of the body.
Not every neck strike is utilized directly upon a (single) specific nerve. What can often produce the emanation of the desired (directional) response (by the uke, when struck), is the anterior scalene muscle(s?). It's several tendons, lay directly “beneath” (under) the Sternocleidomastoid muscle (Shown in the 2nd picture) which I presume is why everyone insists upon trying to “pound” the ever lovin' “piss” out of it, LOL.
Although appearing to be separate (individual) muscles in this picture that I found (Shown below), these are (apparently) all a part of a singular muscle (the anterior scalene muscle) with individual tendon attachment locations. When you “probe” about (on your own neck, LOL), it's possible to feel many of those individual attachments (tendon's). Each of these (individual) tendons are susceptible to being twisted and/or plucked (similar to a guitar string).
Laying across/on top of those tendons, is the Sternocleidomastoid muscle (see picture below). This muscle has numerous striking locations along the entire length of the muscle (in different directions and performed in different manners).
Additionally, please ignore the ridiculous nonsense that is the (evidently) popular “Kyusho Recovery”(?) techniques and courses that are being sold (in seminars/videos) these days. It is the latest “fad” to sell to students (that you/they can then become “certified”, LOL) to “treat” your (victims) recipients after your neck-strike practice.
You will be far better served to go to a Red-Cross first aid course (and get certified, it's actual training, unlike this crap that they're teaching at these “kyusho” courses). Once you take the Red-Cross course, you can openly laugh at the stupidity of what these moron's are doing (to essentially “treat” a subject who has physically responded exactly as if they had just “feinted”). What's the “first” thing that these guy's do? (they have them sit up, instead of having them lay down). Otherwise, it wouldn't be nearly as dramatic (can't have them recovering too quickly, LOL).
Regardless of a strike's intended direction of manipulation (be it a probe and hook, or even a “pluck”) the strike's effectiveness is dictated more by direction, and manipulation manner (than by any blunt trauma). This can be extremely subtle, and will have the appearance of being a (heavy/hard) impacting strike (which they are not, or certainly don't need to be).
Yet, performing a Hard (muscular) strike is what 98% of the “neck-strike” video's are telling you to do. You can/will produce a “reaction”, just not one that could be as easily utilized to your own advantage (as well as requiring you to expend far more energy, to achieve far less response).
Until a student has experimented with several different body “types”, it will be (equally) difficult to (immediately) recognize these locations. This is why we tell our students to “probe” their own body (take that, how ever you want to, LOL). I've provided several pics of individual's "necks" that I found on the internet. You can (easily) see how some are easier (and more obvious) to differentiate the described locations, depending upon the physical state and/or angle of motion, that the individual is in (relaxed, or stretched out, body type etc.).