CV 21: XUANJI (North Star)
On the mid-line of the sternum, midway between CV 22 and CV 20, or midway between the articulations of the left and right rib with the sternum. Xuan here means rotation and ji here means axis, this is the name given to the 2nd and 3rd stars of the big dipper, opposite the Zigong star. This Pt is above ZIGONG PT so is called XUANJI.
Use CV 22, it is much more appropriate. Local pain and Qi drainage when CV 21 is struck. Not a point I would bother with as CV 22 is just above it.
CV 22: TIANTU (Heaven's Prominence)
In the depression 0.5cun above the suprasternal notch, between the left and right sternocleidomastoid muscles. In it's deep position in the sternohyoid and sternothyroid muscles.
This is one of the most deadly points in the body. It will cause immediate suffocation and brain death. Only an experienced acupuncturist is advised to needle this point using a special method of tilting the head back. This is a window of the sky point. This point at the least will cause emotional trauma such as fear or grief. This strike will also affect he lungs greatly causing coughing and gasping for air in the least and death in the most. This is one of the points that I teach how to strike in womens self defence classes and those workshops for law enforcement officers where only a short time is allocated (as usual) to their learning self defence.
CV 23: LIANQUAN (Modesty's Spring or Screen Spring)
Above the Adams apple, in the depression at the upper border of the hyoid bone. In the depression between the pharyngeal prominence and the lower margin of the hyoid bone.
This is a concentration point of shao yin. (Heart/Kidney). Although because of this location, you would not really worry about electrical damage as the physical damage to this area will cause death through suffocation anyway. It is possible to build up a whole heap of grizzle in this area by performing the old wrestlers bridge often. This is what tricksters do who perform the old chopstick in the neck trick. The chopstick is forced straight in where the heavy concentration of grizzle is. However, we strike in an upward manner thus getting past the grizzle and into the trachea.
CV 24: CHENGJIANG (Contains Fluids or Receives Fluids)
In the depression in the centre of the mentolabial groove, this is the depression below the middle of the lower lip between the orbicularis oris and mentalis muscle muscles.
Strike from the recipients left to his right using either the tips of the fingers of the one knuckle punch. This will cause extreme nausea vomiting and can even cause a knock out. The recipients right to his left will also cause extreme nausea and vomiting with great pain down the left side of the abdomen, this can be so great that he will buckle up in pain. When struck straight in will knock his teeth out!.
It can be seen that this meridian is the most dangerous. Most people know that the centre line points are dangerous, but few know why. In practice, stay away from these points, pull your punches short of the points, as even mild pressure to some of the more sensitive points will cause damage, and long term effects.