The system of muscles in the hand and fingers of a human by far in the world of biology is the most well developed structure in the animal kingdom. The human hand can perform any possible movement and the fingers alone are capable of producing tremendous amount of strength. But for all we know, we may always use fingers every day and despite the amount of force the human finger can apply, there are actually no muscles that can be found within the fingers. Our five fingers do not have muscles, it is simply a group of bones cloaked with skin, but we are able to move them because of a number of reasons. Basically, our ability to move our fingers is not as direct as it may seem, because our fingers do not have muscles, there motion in other words is controlled by another set of muscles that are not found in the fingers themselves. In fact, the muscles that control the finger’s ability of motion are found in the hand and also on the forearm.
The cloaked bones of our fingers are connected to the muscles of our hand and arm through thin strings called as tendons. Tendons are the basic structures that are responsible for the motion of our fingers, a damage tendon can result to numerous diseases like trigger finger which will lead to the inability of a finger to move, just an example of how vital the tendon’s role are. The tendons act like strings for our fingers which are controlled by the muscles in our hand and arm, as we flex, the string is pulled resulting to the motion of our fingers. The strength of our fingers in short are determined by the strength of the muscle in arms, which makes grip exercise devices just the same as working out with dumbbells. Without going to much deeper technical terms, the tendons of the fingers can be grouped into two, the intrinsic and the extrinsic. The extensors are the long muscles that are located starting from the forearm to the fingers. Their main role is to perform the straightening of the fingers, while the intrinsic muscles are shorter ones compared to the extensors. The thumb is composed of a number of tendons which gives it the ability of grasping. Other fingers do also have addition tendons which gives the ability of fingers of further movement.
In order to fully understand the motor characteristics of fingers, it is necessary to learn the origin of the motion. To start off, the most complex structure of the five fingers which is the thumb is controlled by the thenar muscles. The thenar muscles are a group of intrinsic muscles that are found within the compartment of the thenar, slightly distinguished from other muscles because it is separated by a wall called the fascia. There are four different types of specific muscles under the specification of the thenar group, without going to the more technical aspects, one of the four types is the Flexor Pollicis Brevis, and this is the basic muscle that gives the thumb its ability to simply flex in its usual position, the fully straight stretch of the thumb. Second, Opponens Pollicis is the muscle that gives the thumb another mode of motion. This allows the abduction of the thumb. This is the movement done when you are trying to reach the pinky. The two other muscles are the Abductor Pollicis Brevis and Adductor Pollicis, these two muscles are highly different from one another, and they differ in structure mainly. The Abductor Pollicis Brevis is a sheath of muscle while the Adductor Pollicis has two heads basically, not going into more technical aspects, these muscles give the thumb its ability to abduct, the motion while grouping with other fingers or when the thumb comes close to the pointer finger. The thenar muscles can be seen just by looking at the base of the thumb, the large area and bulk generated are the muscles that mainly control the motions of the thumb.
The exact opposite of the thumb which is the pinky is controlled by another set of muscles which are called hypothenar muscles. These are intrinsic muscles that compose the medial side of the hand. They are controlled by the nerves of the deep branch of an ulnar nerve. Under the hypothenar muscles are two intrinsic muscles that give the pinky its different forms of motor motion. The first is the Abductor Digiti Minimi which origins at the pisiform and enters through the base of the pinky finger. It is mainly responsible for the abducting motion, followed by the Flexor Digiti Minimi. This muscle originates from the Hamate and comes close to the Abductor Digiti Minimi muscle. It is the key muscle that gives the pinky the flexing motion, the ability to straighten and stretch the pinky. The Opponens digiti Minimi originates also from the Hamate. What it does is that it pulls and rotates the fifth metacarpal which gives the pinky its ability to oppose the thumb or come in contact with the thumb.
If you are wondering whether the muscles controlling the three different enclose fingers are different, then you are slightly wrong. The muscles responsible for the motion of the ring, index and middle finger are all under in one classification. To start with, the Interosseous muscles which are then also later divided by seven even smaller sub-groups of muscles which are also controlled by the ulnar nerve. There are four dorsal muscles that are responsible for the flexing and three palmar muscles that are responsible for the abducting capabilities of the three fingers. The other type of muscle is the Lumbricals. There are actually four of these and are located between metacarpals. The first and second are controlled by the median nerve while the third and fourth by the ulnar nerve. These muscles give the ability of flexing and extending the three enclosed fingers. All the muscles that compose the hand are responsible for the motion of the fingers, while also the forearm is still partly responsible for some muscles that cause the movement of the fingers, like the long extrinsic muscles.