The structure of the hand and wrist. Anatomical structure of the hand

On closer examination, the structure of the hand, like any other part of our musculoskeletal system, is quite complicated. It consists of three main structures: bones, muscles and ligaments that hold the bones. In the brush there are three departments, namely: wrist, fingers and pastern.

In this article, we will consider in detail the brush: the structure, muscles, and the joints of the hand. Let's start with the description of the bones in its various departments.

Bones of the wrist

Since the hands must perform fairly precise and intricate movements, the structure of the bones of the hand is also extremely complex. In the wrist - 8 small bones of irregular shape, arranged in two rows. In the figure below you can see the structure of the right hand brush.

The proximal row forms an articular surface convex to the radius bone. It includes bones, if we count from the fifth to the large finger: pea-shaped, triangular, semilunar and scaphoid. The next row is distal. It connects to the proximal joint of irregular shape. The distal row consists of four bones: trapezoidal, polygonal, capitate and hooked.

Bones of the pastern

This department, consisting of 5 tubular metacarpal bones, also demonstrates the intricate structure of the hand. The skeleton of these tubular bones is complicated. Each of them has a body, a base and a head. The metacarpal bone of the first finger is shorter than the others and is massive. The second metacarpal bone is the longest. The others decrease in length as they move away from the first and approach the ulnar margin. The bases of the above-mentioned bones of the pastern are articulated with the bones forming the wrist. The first and fifth metacarpals have bases with articular surfaces of saddle-shaped form, others - flat. The head of metacarpal bones, having an articular surface (hemispherical), are articulated with proximal finger phalanges.

Finger bones

Each finger, except the first, which consists of only two phalanges and has no middle, has 3 phalanges: distal, proximal and middle (intermediate). The shortest are distal; Proximal - the longest. At the distal end there is a phalanx head, and on the proximal end - its base.

Sesamoid bone of the hand

In the thickness of the tendons, in addition to the bones mentioned, there are sesamoid, located between the proximal phalanx of the thumb and its metacarpal bone. There are also unstable sesamoid bones. They are located between the proximal phalanges of the fifth and second fingers and their metacarpal bones. Usually, the sesamoid bones are located on the palmar surface. But sometimes they can be found on the back. The bony bone also belongs to the above-named species. Sesamoid bones and their processes increase the shoulder strength of the muscles attached to them.

We examined the structure of the hand and the bone of the hand, and now we turn to the ligament apparatus.

Wrist joint

It is made up of the radius and bones of the proximal wrist: triangular, semilunar and navicular. The ulnar bone is complemented by the articular disc and does not reach the wrist joint. The main role in the formation of the elbow joint is played by the ulna. Then the wrist band is radial. The wrist joint is elliptical in shape. It can lead, lead, flexion and extension. A small passive rotational movement (by 10-12 degrees) is also possible in this joint, but is due to the elasticity of the articular cartilage. Through the soft tissues it is easy to detect the gap of the wrist joint, which is probed from the ulnar and radial sides. With the ulna, you can grope for the groove between the trihedral bone and the ulnar bone. On the radial side there is a gap between the scaphoid bone and the lateral subulate process.

The movements of the wrist joint are closely related to the work of the mid-wrist joint, located between the distal and proximal rows. Its surface is complex, irregular in shape. When flexing and unbending, the volume of mobility reaches 85 degrees. Brushing in the above-mentioned joint reaches 40 degrees, the lead is 20. The wrist joint can perform circumduction, i.e. circular motion.

This joint is strengthened by numerous ligaments. They are between individual bones, as well as on the lateral, medial, back and palmar surfaces of the wrist. The collateral ligaments (radial and ulnar) play the most important role. On the ulnar and radial sides between the bony elevations is the flexor retainer - a special ligament. In fact, it does not apply to the joints of the hand, being a thickening of the fascia. The flexor holder converts the furrow of the wrist into a channel in which the median nerve and tendons of the flexor flexors pass. We continue to describe the anatomical structure of the hand.

Pseudo-metacarpal joints

They are flat-shaped, inactive. The exception is the joint of the thumb. The volume of movements of carpometacarpal joints is no more than 5-10 degrees. They are limited mobility, because well-developed ligament. Located on the palmar surface, they form a stable palmar ligament apparatus, connecting between the wrist and metacarpal bones. There are arched bunches on the brush, as well as transverse and radial. The head bone is central in the ligamentous apparatus, a large number of ligaments are attached to it. The palms are much better developed than the rear ones. The back ligaments connect the bones of the wrist. They form thickened capsules that cover the joints between these bones. Interosseous located in the second row of bones of the wrist.

In the thumb, the carpometacarpal joint is formed by the base of the first metacarpal and polygonal bone. The articular surfaces have a saddle shape. This joint can perform the following actions: withdrawal, reduction, reposition (reverse movement), opposition (opposition) and circumduction (circular motion). The volume of grasping movements, due to the fact that the thumb is opposed to everything else, significantly increases. 45-60 degrees is the mobility of the carpometacarpal joint of this finger when leading and withdrawing, and with reverse movement and opposition - 35-40.

The structure of the hand: metacarpophalangeal joints

These joints of the hand are formed by the heads of the metacarpal bones with the participation of the bases of the proximal phalanges of the fingers. They are spherical, have 3 axes of rotation perpendicular to each other, around which extension and bending, retraction and reduction, as well as circular movements (circumduction) are carried out. Reduction and retraction is possible by 45-50 degrees, and flexion and extension are 90-100 degrees. These joints have collateral ligaments located on the sides that strengthen them. Palms, or additional, are on the palm side of the capsule. Their fibers are intertwined with fibers of a deep transverse ligament, which prevents divergence of the metacarpal heads in different directions.

Interphalangeal joints of the hand

They are block-shaped, and the axes of their rotation run transversely. Extension and bending are possible around these axes. The proximal interphalangeal joints have a volume of flexion and extension, equal to 110-120 degrees, distal - 80-90. Interphalangeal joints are very well strengthened due to collateral ligaments.

Synovial as well as fibrous vagina of the tendons of the fingers

The extensor retainer, as well as the flexor retainer, plays a huge role in strengthening the position of the tendons of the muscles passing under them. This is especially true when the brush works: with its extension and bending. Nature has conceived a very competent structure of the hand. Tendons find support in the aforementioned ligaments from their inner surface. Separation of tendons from bones prevents tie. This allows for intensive work and a strong contraction of muscles to withstand high pressure.

Reducing the friction and slip of the tendons reaching the forearm from the forearm is promoted by special tendon sheaths, which are bone-fibrous or fibrous channels. They have synovial vaginas. The largest number (6-7) is under the extensor retainer. The radial and ulnar bones have furrows that correspond to the location of the tendons of the muscles. And also the so-called fibrous bridges, which separate the channels from each other and pass to the bones from the extensor retainer.

Palmar synovial vagina refers to the tendons of the flexor of the fingers and hands. The common synovial vagina extends to the center of the palm and reaches the distal phalanx of the fifth finger. The tendons of the superficial and deep flexor of the fingers are located here. The thumb has a tendon of the long flexor, located in the synovial vagina apart and passing to the finger along with the tendon. The synovial vagina in the palm region is devoid of muscle tendons that go to the fourth, second and third fingers. Only the tendon of the fifth finger has a synovial vagina, which is a continuation of the common.

Muscles of a brush

In the figure below you can see the muscles of the arm. The structure of the hand is shown here in more detail.

The muscles in the hand are only on the palmar side. They are divided into three groups: middle, large and small fingers.

Since the finger movements require great accuracy, there is a significant number of short muscles in the hand that complicates the structure of the hand. The muscles of the hands of each of the groups will be considered below.

Average muscle group

It is formed by vermicular muscles starting from the tendons of the deep flexor of the fingers and attached to the proximal phalanges, more precisely to their bases, from the second to the fifth finger, if we consider the structure of the arm. The muscles of the arm also come from the rear and palmar interosseous spaces located in the spaces between the bones of the pastern attached to the base of the proximal phalanges. The function of this group is that these muscles are involved in flexing the proximal phalanges of the said fingers. Thanks to the palmar interosseous muscles, it is possible to bring the fingers to the middle finger of the hand. With the help of the rear interosseous they are diluted to the sides.

Muscles of the thumb

This group forms the eminence of the thumb. These muscles begin near the nearby bones of the pastern and wrist. As for the thumb, its short flexor is attached near the sesamoid bone, which is near the base of the proximal phalanx. The thumb opposite the muscle goes to the first pastern bone, and the leading thumb is from the side of the inner sesamoid bone.

Muscles of the thumb

This group of muscles forms an elevation from the inside of the palm of the hand. These include: a finger that removes the pinkie, opposing the little finger, a short palm, and a short flexor.

They originate from the nearby bones in the wrist. These muscles are attached to the base of the fifth finger, more precisely its proximal phalanx, and to the fifth metacarpal bone. Their function is reflected in the title.

In the article, we tried most accurately to present the structure of the hand. Anatomy is a fundamental science, which, of course, requires more careful study. Therefore, some issues remained uninformed. The structure of the hand and wrist brush is a topic that interests not only the physicians. Knowledge of it is also necessary for athletes, fitness instructors, students and other categories of people. The structure of the hand, as you have noticed, is quite complex, and you can study it for a long time, relying on various sources.