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Humans normally have five digits on each extremity. Each digit is formed by several bones called phalanges, surrounded by soft tissue. Human fingers normally have a nail at the distal phalanx. The phenomenon of polydactyly occurs when extra digits are present; fewer digits than normal are also possible, for instance in ectrodactyly.
The human hand usually has five digits: four fingers plus one thumb; [3] [4] however, these are often referred to collectively as five fingers, whereby the thumb is included as one of the fingers. [ 3 ] [ 5 ] [ 6 ] It has 27 bones, not including the sesamoid bone , the number of which varies among people, [ 7 ] 14 of which are the phalanges ...
Human hand anatomy (pentadactyl) In biology, dactyly is the arrangement of digits (fingers and toes) on the hands, feet, or sometimes wings of a tetrapod animal.The term is derived from the Greek word δακτυλος (dáktylos) meaning "finger."
[5] [6] [Note 2] Chinese number gestures count up to 10 but can exhibit some regional differences. In Japan, counting for oneself begins with the palm of one hand open. Like in East Slavic countries, the thumb represents number 1; the little finger is number 5. Digits are folded inwards while counting, starting with the thumb. [7]
The ordinal numbers of the fingers of the human hand are numbered ambiguously in the English language. This is due to two competing finger numbering systems that can be used. For instance, the first finger might refer to either the thumb or the index finger, depending on the context.
Most tetrapods have five digits (pentadactyly), [1] [2] and short digits (i.e. significantly shorter than the metacarpal/metatarsals) are typically referred to as toes, while those that are notably elongated are called fingers. In humans, the fingers are flexibly articulated and opposable, serving as an important organ of tactile sensation and ...
A real differentiation appeared an estimated 70 mya in early primates, while the shape of the human thumb CMC finally appears about 5 mya. The result of this evolutionary process is a human CMC joint positioned at 80° of pronation, 40 of abduction, and 50° of flexion in relation to an axis passing through the second and third CMC joints. [40]
The digits at the borders of the cleft might be syndactilyzed, and one or more digits can be absent. In most types, the thumb, ring finger and little finger are the less affected parts of the hand. [7] The incidence of cleft hand varies from 1 in 90,000 to 1 in 10,000 births depending on the used classification.