Hand of whether the three digits of the bird hand involved the same homologous loss of two digits as in the dinosaur hand. The human hand normally has five digits: four fingers plus one thumb; these are often referred to collectively as five fingers, however, whereby the thumb is included as one of the fingers. It has 27 bones, not including the sesamoid bone, the number of which varies between people, 14 of which are the phalanges (proximal, intermediate and distal) of the fingers and thumb. The metacarpal bones connect the fingers and the carpal bones of the wrist. Each human
Normal coordinates a normal neighborhood of a point "p" in "M". A normal neighborhood "U" is a subset of "M" such that there is a proper neighborhood "V" of the origin in the tangent space "TM", and exp acts as a diffeomorphism between "U" and "V". On the normal neighborhood "U" of "p" in "M", the chart is given by: formula_3 The isomorphism "E" can be any isomorphism between the two vector spaces, so there are as many charts as there are different orthonormal bases in the domain of "E". The properties of normal coordinates often simplify computations. In the following, assume