Occasionally accessory bones are found in the carpus, but of more than 20 such described bones, only four (the central, styloid, secondary trapezoid, and secondary pisiform bones) are considered to be proven accessory bones. Sometimes the scaphoid, triquetrum, and pisiform bones are divided into two.
perforce definition: by or through necessity; necessarilyOrigin of perforceMiddle English par force from OFr: see per and force...
Perveance is a notion used in the description of charged particle beams. The value of perveance indicates how significant the space charge effect is on the beamâs motion. The term is used primarily for electron beams, in which motion is often dominated by the space charge.