The human hand skeleton can be divided into 4 sections. The upper is the belt of the upper limb. This includes the shoulder blade and collarbone. Next comes the actual anatomical shoulder, that is, the section of the humerus. The next section is the forearm, consisting of the ulna and radius bones. The last one is the bones of the hand. The skeleton of the left hand is a mirror image of the skeleton of the right.
Section overview
Let's consider the skeleton of a hand for each section. The scapula and clavicle are connected to each other, and the ball joint connects them to the humerus. But not only the humerus joins them. They serve as an attachment point for the muscles that are responsible for the movement of the hand.
Next comes directly the humerus. The radial and ulnar joints are attached to it through the elbow joint. The latter are mobile relative to each other. With the hand positioned with the palm facing inward, these bones are parallel, but when the palm is turned forward, they shift and cross.
The skeleton of the hand has the most complex structure. The composition includes 27 bones. These elementsadditionally divided into several groups: the wrist, metacarpus and phalanges of the fingers, connected through the interphalangeal joints. It is the complexity of this apparatus that allows the hand to be so versatile and skillful. It can do rough work with mechanical operations, but it also allows you to perform fine precise movements.
Detailed structure of the shoulder girdle
The skeleton of the arm in the shoulder girdle is represented by the scapula and collarbone. It is the area of their placement and connection with the humerus that is called the shoulder in everyday life. However, anatomically, the shoulder is precisely the humerus, and these elements make up the girdle of the upper limb. But, considering the skeleton of the human hand, the structure must be studied together with the shoulder girdle, which significantly affects the functionality.
Scapula
The shoulder blade is a flat bone from the side of the back. It has a triangular shape with superior, lateral and medial margins and inferior, superior and lateral angles. It is the thickened lateral angle that is provided with the articular cavity, where the articulation of the scapula with the head of the humerus located in the next section takes place. Slightly above the cavity is the neck of the scapula, which looks like a narrowed place. The articular cavity is also surrounded by tubercles - subarticular and supraarticular.
The scapula itself has a somewhat concave surface - a subscapular fossa - in the area of \u200b\u200bthe ribs from the side of the chest. But on the back surface there is an awn that runs along the shoulder blade from the inner edge to the outer corner. On the sides of the spine, supraspinatus and infraspinatus are distinguishedpits where muscles with the same names are attached. Outwardly, this spine passes into the shoulder process located above the shoulder joint, called the acromion. The scapula is also equipped with a coracoid process, facing forward and serving to attach ligaments and muscles.
Clavicle
The clavicle is a tubular bone curved in an S-shape. Has a horizontal position, goes in the upper front of the chest near the neck. The medial sternal end is attached to the sternum, and the acromial lateral end is connected to the scapula. Also, fastening is carried out by muscles and ligaments, which causes the presence of roughness on the lower surface, namely the line and tubercle.
The structure of the shoulder
Behind the shoulder girdle is the skeleton of a human hand. The shoulder is formed precisely by the humerus. This is a tubular bone, rounded in cross section on the upper side and triangular closer to the bottom. The upper end is crowned with a head in the form of a hemisphere, which is turned towards the shoulder blade. The head has an articular surface. A little lower is the anatomical neck of the bone and two tubercles for muscle attachment. A large tubercle is turned outward, and a small tubercle goes anteriorly. A ridge goes down from each, but between it and the tubercles there is a groove for the passage of the tendon. The narrowest part of the bone is called the surgical neck.
The body of the bone is called the diaphysis. Deltoid tuberosity on its outer surface is intended for attachment of the deltoid muscle. And the back surface is decorated with a furrow of the radial nerve, running slightly in a spiral.
Dist althe epiphysis is the lower end of this bone. Here the condyle and the articular surface are formed, with the help of which the bone is connected to the next section. Humerus block - the medial part of the joint that connects to the ulna. The lateral part of the spherical shape - the head of the condyle - is connected to the radius. Two pits are provided above the block, where the processes of the ulna go when the arm moves, they are called the fossa of the coronoid and olecranon. Also near the distal end there are epicondyles (lateral and medial) where ligaments and muscles are attached.
The structure of the elbow and forearm
The forearm is the part of the limb from the elbow to the hand. In everyday life, this part was often called the elbow, including being used as a measure. The elbow joint includes the ulna and radius of the forearm and the humerus itself. The skeleton of the hand of this department is represented by the ulna and radius bones. They are movably connected to each other: the radius got the opportunity to rotate around the elbow when the arm moves. Thanks to this, the brush can be rotated up to 180º.
Ula
The ulna is trihedral in shape. The upper end is thickened, provided with a block-shaped notch in front to articulate with the humerus. The lateral edge ends with a radial notch, which is needed to connect with the head of the second bone of the forearm - the radius. On both sides of the block-shaped notch are the coronoid anterior process and the ulnar posterior process. Under the anterior process there is a tuberosity for attaching the shoulder muscle. At the distal inferiorthe end of this bone is the head. The articular surface on its radial side serves for articulation with the radius. Also, the head of the ulna is provided with a styloid process at the posterior margin.
Radius
The radius received a thickening at the lower end, and not at the upper end, like the ulna. On the top is the head of the radius, which allows you to connect with the humerus. The upper surface of the head has a fossa, which is needed for articulation with the head of the condyle located on the humerus. The articular circumference along the edge of the head allows you to connect with the ulna. The head tapers downward, passing into the neck of the radius. On the inside, just below the neck, a tuberosity allows the biceps brachii to attach to the tendons.
The lower end of this bone is provided with a carpal articular surface that connects this section with the hand. There is also a styloid process, turned outward, and on the inside there is an ulnar notch, designed for articulation with the corresponding head of the ulna. Also, the skeleton of the hand in this place contains a limited interosseous space enclosed between the sharp edges of the bones of the forearm.
Hand
The skeleton of the human hand is divided into the wrist, metacarpus and the fingers themselves. Each department is made up of a series of bones and movable joints. This structure allows you to perform a variety of actions with your hands, deftly and quickly work even with small details.
Wrist
The skeleton of the hand starts at the wrist. It contains eight bones at once, small in size and irregular in shape. These are spongy bones. They are arranged in two rows. Here, the pisiform, trihedral, lunate and scaphoid bones of one row are distinguished, and the second is hamate, capitate, trapezoid and polygonal. The first proximal row serves as the articular surface necessary for articulation with the radius. The second row is distal, connected to the first irregularly shaped joint.
Being located in different planes, the bones of the wrist form the so-called carpal groove from the side of the palm, and a bulge is noted on the back side. From the furrow of the wrist come tendons, which are responsible for the work of the flexor muscles.
Pastern
The pastern is formed by five metacarpal bones. These are tubular bones, consisting of a body, base and head. The skeleton of the human hand is distinguished by a large opposition of the thumb to the rest and its better development, which significantly increases the capabilities of the limb. A shorter, but more massive bone goes to the thumb. The bases of these bones are connected to the bones of the wrist. In this case, the articular surfaces for the extreme fingers have a saddle shape, and the rest are articular surfaces of a flat type. The heads of the hemispherical articular surface connect the metacarpal bones to the phalanges.
Fingers
The bones of the fingers consist of two or three phalanges: the first one is made up of two, and the rest - of three. The length of the phalanges decreases with distance from the metacarpus. Each phalanx is made up of threeparts: bodies with a base and a head at the ends. The phalanges end with articular surfaces at both ends, which is due to the need for articular connection with further bones.
Between the proximal phalanx and the metacarpal bone of the thumb (first) finger, there are also sesamoid bones hidden by tendons. It is worth noting that sometimes there is an individual structure of the hand: the skeleton of the hand can be supplemented with other elements. Sesamoid bones may also be in a similar location near the second and fifth fingers. Muscles are attached to these elements (as well as to bone processes).
