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Thumb

Synonyms: pollex, digitus I manus, digitus primus manus
German: Daumen

1 Definition

The thumb is the most radially situated finger of the hand. Its main difference compared to the other fingers is the presence of only two phalanges (digital bones) in the thumb.

2 Anatomy

Even though the thumb is the shortest finger, it is essential to most grasping movements due to the possibility of opposition. The wide range of motion is mainly achieved by the interaction of two joints:

The thumb can exert counter-pressure on the other fingers, allowing them to grip objects. Brain regions dedicated to sensitivity and motor function of the thumb are more developed than those of the other fingers. This is also related to the large number of muscles used to move the thumb:

Those muscles are either located in the thenar eminence of the hand (a region at the base of the thumb, on the palmar side), which is why they are called thenar muscles or they are situated on the forearm and connect to the thumb by way of longer tendons.

3 Clinical relevance

If the thumb did not develop properly in the embryo or in case of traumatic amputation, a surgical technique called pollicization can be used to create a functional thumb.

Specialties: Anatomy

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