The index finger is the second finger of a human hand. It is located between the first and third digits, between the thumb and the middle finger. It is usually the most dextrous and sensitive finger of the hand, though not the longest – it is shorter than the middle finger, and may be shorter or longer than the ring finger – see digit ratio. "" literally means "pointing finger", from the same Latin source as ; its anatomical names are "index finger" and "second digit".
Anatomy
The index finger has three phalanges. The index finger does not contain any muscles, but is controlled by muscles in the hand by attachments of tendons to the bones.
Uses
A lone index finger held vertically is often used to represent the number 1, or when held up or moved side to side, it can be an admonitory gesture. With the hand held palm out and the thumb and middle fingers touching, it represents the letter d in the American Sign Language alphabet.
Pointing
Pointing with index finger may be used to indicate an item or person. Around the age of one year, babies begin pointing to communicate relatively complex thoughts, including interest, desire, information, and more. Pointing in human babies can demonstrate the theory of mind, or ability to understand what other people are thinking. This gesture may form one basis for the development of human language. Non-human primates, lacking the ability to formulate ideas about what others are thinking, use pointing in much less complex ways. However, dogs and elephants do understand finger pointing. In some countries, particularly the Ethnic Malays in Malaysia, pointing using index finger is rude, hence thumb is used instead.
Greeting
In the Netherlands sticking up your index finger with your palm faced towards someone is a greeting.
Index finger in Islam
In Islam raising the index finger signifies the Tawhīd, which denotes the indivisible oneness of God. It is used to express the unity of God. In Arabic, the index or fore finger is called musabbiḥa, mostly used with the definite article: al-musabbiḥa. Sometimes also as-sabbāḥa is used. The Arabic verb سَبَّحَ - which shares the same root as the Arabic word for index finger - means to praise or glorify God by saying: "Subḥāna Allāh".
