It wil depend upon which murthi you are talking about and which pose. For example the Shiva-Nataraja.
The upper raised right hand carries a small drum like an hour glass, for the beating of rhythm. This connotes Sound, the vehicle of speech, conveyor of revelation and divine truth. Sound is associated with Ether, the first of the five elements. Out of it unfold the other elements. Sound and Ether signify the first moment of creation.
The upper left carries a tongue of flame with a half moon posture of the fingers (ardhacandra-mudra). Fire is the element of destruction of the world. On the one side of Shiva, creation, on the other side, destruction.
The other right hand is the 'fear-not' gesture (abhaya-mudra) - giving protection and peace.
The other left lifted across the chest, pointing downwards to the uplifted left foot. The uplifted foot signifies refuge and liberation to the devotee.
The other parts of the Shiva-Nataraja are also pregnant with meaning.
Hand gestures are referred to as Mudras. They are common to both Hindus and Buddhists. For more information on specific mudras, Wikipedia is a good starting point - https://en.wikipedia.org/wiki/Mudra