Chinchinyuen There 2 points on each foreleg, located on the medial and lateral digital veins just dorsal to where they cross the the fetlock joint space.

Traditionally bled. (2-3cc).
My Graphic
In practice, to locate these 4 points, you need to know where the fetlock joint-space is. To pinpoint the space you should lift the foot and flex and extend the fetlock while palpating on the lateral aspect of it.

Whilst doing this, your finger should be able to distinguish the space between the distal end of the 3rd metacarpal bone and the proximal end of the 1st phalanx.

Repeat this procedure on the medial aspect of the fetlock.

Chinchinyuen is found both
(1) where the medial digital vein crosses the space and
(2) where the lateral digital vein crosses the space.

It may help in some horses to compress the leg above the fetlock to help engorge these 2 veins.

Bleeding is performed by "cutting" a small incision into the wall of the vein using the cutting edge of a hypodermic needle.

Lasers are sometimes used instead of "bleeding".

Acupuncture needles are sometimes substituted for bleeding in which case they are inserted
close to but "underneath" the vein, to lie just within or in close contact with the fetlock joint space.

13mm needles are most appropriate in this case.