In A Dictionary of Symbols, J. E. Cirlot states, "Of great importance is the fact that the hand has five fingers, firstly, because if its broad analogy with the human figure (composed of four extremities plus the head) and, secondly, by reason of the symbolism of the number five (denoting love, health and humanity)" (pg. 137). The meaning or symbolism of the hand is explained by Gertrude Jobes, "The palm heel is assigned to the underworld goddess, the center is assigned to Mars as it grips weapons and its principal lines form the initial M. The forefinger, digit or index finger is that of direction, fortunate guidance, or rule, assigned to Jupiter. Called furze or oak finger. The middle or fool’s finger assigned to Saturn, the Christmas Folly, and death. Called heather thinker. The fourth or wedding ring finger is also that of the leech or physic, and anciently physicians mixed medications with it on the theory no poison could adhere to it without communicating information. Assigned to Apollo, the healer, called gold or poplar finger. The small or ear finger, anciently was used by priests to stop the ear as an aid to inspiration, thus a divinatory finger. Assigned to mercury as a conductor of dead souls into the yew tree" (pg. 717).
In Catholicism, the third finger represents Christ and salvation as it is the tallest finger; the index finger symbolizes the Holy Ghost; the "two remaining fingers denote respectfully the divine and human nature of Christ" (Jobes). Walker writes "Our common symbol for silence, placing the finger on the lips, dates back to a Greek understanding of an Egyptian god. To the Egyptians, the newborn sun of each day was the child Horus, shown at dawn as a small toddler sucking on his finger. The Greeks took this as an image of secrecy concerning his Mysteries, enjoining silence. They called the child Horus Harpocrates, God of Silence, and invoked him by the finger-to-mouth gesture" (pg. 310). In Greek lore, the index finger on the mouth is the symbolic attitude of Polyhymnia, the muse responsible for songs and dances to the deities, and Nemesis, the goddess of punishment and vengeance. Commonly, the index finger was used to curse enemies and currently it is considered rude to point with the index finger or to shake it at someone.
In Greek mythology, the Dactyls were spirits born from the goddess Rhea’s fingerprints when she gave birth to Zeus. From her right hand spring five male Dactyls and from her left, five female Dactyls. There is a question of which Dactyl is associated with which finger. "According to some systems, the index finger, middle, ring, and little fingers were assigned to Apollo, Jupiter, Venus, and Mercury, respectively. Others referred to call them Jupiter, Saturn, Apollo, and Mercury; another instance of Goddess-erasure. However, the Venus/Apollo finger is still connected with the mythic ‘love vein’ and wears the wedding ring" (Walker).
"A hand with three fingers, or a mutilated hand, depicts the phases of the moon; with fingers extended and ending in the sun’s rays it is the life-giving power from heaven or the sky" (Copper, pg. 78). In Christian art, a hand emerging from a cloud represents divine power.
Hand image from: https://www.prints-online.com/palmistry-map-hand-570381.html