Many people use their thumbs every day to perform a myriad of functions. This type of grip is important for moving small and delicate objects, such as when writing with a pen. The thumb works opposite to one or more fingertips to allow the fingers to grip objects. The ability of the thumb to position opposite the fingers allows humans to hold and move heavy objects in a controlled way, such as when lifting weights at the gym.Ī precision grip only requires the fingertip to apply force between the fingertips to smaller objects. Power grips require using the whole hand for higher stability and power on larger objects. There are two main types of grips: power and precision grips. The opposable nature of the thumb and the thenar muscles provide the dexterity and strength to perform these actions. Its unique position and proportional length allow the thumb to firmly contact the other fingers and other objects. With the rest of the hand’s digits, the thumb plays a crucial role in performing coordinated hand movements for precise tool use. The thumb’s primary function is to either work with or against the other fingers to manipulate objects and perform actions such as pinching or grasping. The five intrinsic muscles, also known as the thenar muscle group, consists of: Experts can divide these into two groups: the extrinsic muscles in the forearm and intrinsic muscles in the hand. Nine muscles contribute to the movement of the thumb. This joint allows people to the thumb away from and towards the hand. The carpometacarpal (CMC) joint is where the metacarpal meets the carpal, or wrist, bones. This joint allows a person to bend and extend the thumb. The metacarpophalangeal (MP) joint is where the metacarpal meets the phalanges. There are also two more joints where the thumb joins the hand, which aids movement. This joint allows a person to bend the tip of their thumb. The interphalangeal joint (IP) is present at the tip of the thumb, just before the fingernail starts, and is similar to the distal interphalangeal joint of the other four fingers.
The thumb then connects to the hand bone, or thumb metacarpal.Īs a result of only having two phalanges, the thumb only has one joint, while the other fingers have two joints. The second bone - proximal phalange - then extends from the knuckle to the base of the thumb. The first bone - the distal phalange - extends from the tip of the thumb to the knuckle.
As with the rest of the hand, the thumb consists of many different structures that allow for movement and dexterity.Įach finger has three bones, or phalanges, except for the thumb, which instead has two phalanges.
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