The forearm where is the person?

The forearm is a section of the upper limb, consisting of two bones and bounded by two joints. Often students confuse the location of the shoulder and forearm in the anatomy of a person. In order to understand, consider the structure and functions of the portion of the upper limb on the forearm.

Anatomy

On the average, the schools begin to study the course of human anatomy. This is a very interesting and at the same time an extensive section of biology, which requires a qualitative assimilation of knowledge. Human anatomy is a science that considers the structure of an organism, its functions and vital activity in general.

About where the forearm of a person is, the skeleton model or the atlas of anatomy will tell. Having carefully studied the name, location, types and purposes of bones, it is easy to understand the structure of the upper limb of a person - the hand.

The skeleton's mobility is provided by the muscles that are attached to the bones. Considering the forearm, where there are many different types of muscle tissue, you can understand how the hand comes into motion. Nerve impulses contribute to the contraction of muscles, which are taken by the nerves located in the forearm.

The forearm: where is it? Photo of a human skeleton

So, a bit of theory. On the question of where the forearm is located in person, an anatomical atlas or skeleton mock-up will help. The forearm bones are one of the components of the upper limb of a person, playing an important role in the mobility of the hands. Having carefully studied the image of the skeleton, it is easy to see where the shoulder and forearm are.

From the name it can be guessed that the forearm is located below the bones of the shoulder, it precedes it and together forms the basis of the upper limb of a man. In order to understand the anatomy of the upper limb, it is necessary to study the bones that make up it.

Forearm bones

Part of the upper limb - the forearm, where there are two bones, has a fairly simple structure. Its tubular long bones form: the elbow and the ray, each of which has its own structural features.

What you need to know about the structure of tubular long bones:

1. They consist of diaphysis, metaphysis and epiphysis. Diaphysis - the middle elongated part of the bone, which has a cylindrical or trihedral shape. Metaphysis is the interval between the diaphysis and the epiphysis. Epiphysis is a thickened end, necessary for joints with the joint.
2. The epiphyses have an articular surface covered with articular cartilage.
3. Epiphyses, depending on the location of the bone, can be proximal (upper) and distal (lower).
4. It is at the expense of the metaphysis and the cartilaginous tissue located on it that the tubular bones grow in length.
5. The epiphysis is a spongy substance, and the diaphysis is compact.

The body of the ulna and radius has a triangular shape, which means the presence of three surfaces. The front part of the bone is facing forward, the back is facing back. The location of the third side of the radial and ulnar bone varies.

Structure of the ulna

We have already found out that the forearm is where two long tubular bones are located, connected on both sides with joints. The third side of the ulna is called the medial and is turned inward, as are its edges.

The ulna is located in the outer part of the hand, which is called the medial position. For example, if we consider the limb from the left and right sides, then the left forearm contains the ulna bone on the left, and the right forearm on the right. In other words, the ulna is in the forearm from the little finger.

The upper epiphysis of the ulna is thicker than the proximal epiphysis of the radius and is articulated with it by the block-shaped notch, which is restricted by two processes: coronary and ulnar. From the inside of the coronoid process there is a radial notch, intended for the head of the radius. The joint, together with the articular surface and cartilage, forms the elbow joint, which ensures flexion and extension of the forearm.

The lower epiphysis, on the contrary, is thinner than the distal epiphysis of the radial bone and connects to it with the help of an articular circle, and then passes into the wrist joint.

Structure of the radius

If the ulna is located medially, then the ray of the third is not given: it is located on the inner side of the hand, ie, it is located distally. For example, the left forearm (where the ulna is located on the left) contains the radius of the bone on the right. In other words, the radius is located on the side of the thumb.

The third side of the radius is called lateral, it is turned outward. The upper epiphysis consists of a head with a small indentation in the center, designed to connect with the humerus of the humerus. The distal epiphysis contains the ulnar incision from the outside for connection with the ulnar bone head.

Connection of the bones of the forearm

An important role in the anatomy of the tubular bones of the forearm is played by the way they are connected together. The joints provide movement of the radius around the ulna. The bone can move towards the inner or outer side, while the wrist and elbow joint always act together.

When the motion is made, the ray bone describes an elbow with an arc of 140 degrees. At the same time, the brush and shoulder are shown, albeit in slight motion, that in the total amount from 220 to 360 degrees of the volume of movements. It is the possibility of such rotation that allows a person to make various movements of the upper limbs.

An important place in the connection of the bones of the forearm is the interosseous membrane, consisting of collagen fibers. It is located between the crests of the radial and ulnar bone and keeps them in such a way that it does not constrain movements.

Shoulder and forearm

The popular understanding of the shoulder arrangement introduces confusion at the beginning of the study of human anatomy. The fact that everyone is accustomed to be considered a shoulder, in medicine is called the shoulder girdle, or the shoulder. Then where is the shoulder, and where is the forearm? The shoulder is the portion of the upper limb from the shoulder to the elbow joint, through which the humerus is connected to the bones of the forearm.

The shoulder is connected to the radius by the lateral part of the articular surface, which has the form of a ball. This is the head of the humerus of the humerus. With the ulna bone, the shoulder is joined by the medial part, forming a block of humerus. The venous and ulnar processes enter the block in front and behind, respectively. Above the block there are pits, in which, during the bending or extension of the elbow, there are appendages.

Muscles of forearm

Where a person has a forearm, we have already figured out. Let us consider in more detail which muscles are involved in this segment of the upper limb. Depending on the movements, the muscles of the forearm can be divided into:

• Pronators - providing the movement of the radial bone in the inner side;
• Arch supports - allowing the radius to move to the outside;
• Flexors and extensors of the hand;
• Flexors and extensors of fingers.

The named groups of muscles unite in two basic categories depending on their position: front and back.

Fore muscles of the forearm

The front muscles that drive the forearm are where the ray is drawn inward. The group includes muscle flexors. The superficial layer of the muscle tissue of the anterior muscles begins with the medial part of the epicondyle of the shoulder. Deep muscle layers begin on the bones of the forearm and the membrane between them. The pronators are attached to the radius.

Muscle tissue is closer to the humerus, more pronounced, and near the wrist band is mainly represented by tendons.

The superficial layer of the anterior muscles is:

1. Rounded pronator - participates in flexing the forearm, and also facilitates its rotation inside (palm turns down).
2. The brachial muscle participates in the process of supination and pronation, in flexion of the forearm. It originates from the shoulder bone and is attached to the distal radius.
3. Radial wrist flexor - participates in the flexion of the wrist and partially rotates it inside.
4. Palmar long muscle - flexes the wrist.
5. The ulnar flexor of the wrist - is involved in bringing the brush into motion and bending it.
6. The superficial flexor of the fingers participates in the bending of the middle phalanges of the fingers.

A deep layer of anterior muscles is represented by a long flexor of the thumb, a deep flexor of the fingers and a square pronator. The forearm, where there are many muscles involved in the movement of the upper limb, determines the dexterity and variety of actions.

Hind muscles of forearm

Back muscles of the forearm are the arch supports and extensors. The superficial layer of muscle tissue consists of muscles:

1. Radial extensor of the hand - participates in flexion of the forearm at the elbow and extension of the wrist.
2. Radial extensor of the hand - participates in the extension of the wrist and its retraction.
3. Extensor of fingers.
4. Extender of the little finger.
5. The elbow extensor of the hand - is involved in the lead of the wrist towards the elbow and its extension.

The deep layer of the posterior muscles of the forearm is represented by the arch support, the long muscle (participates in the lead of the thumb), the short and long extensor of the thumb and the extensor of the forefinger.

Nerves of the forearm

The forearm, where there are many muscles, is also the place of passage of nerves. Let's consider the basic nerves located in this area, and their functions:

• Musculo-cutaneous - its branches are in the elbow joint, below it it descends in the form of a cutaneous lateral nerve. Innervates the skin of the forearm.
• Median - the branches are located in the elbow joint and in the anterior muscles of the forearm. It innervates the joints of the hand, the muscles of the thumb.
• Loktevoy - located next to the ulnar artery, innervates the ulnar flexor of the wrist. Below is divided into branches that innervate the palm from the inner and outer sides.
• Medial cutaneous - innervates the skin of the forearm, originates from the medial fascicle.
• Radial - a deep branch of this nerve innervates the extensor muscles of the forearm.

Fractures of the bones of the forearm

The bones of the forearm are thin enough, so that they easily break down even with small injuries.

Fractures of the forearm can be divided into several types:

1. Fracture of the ulnar process - arises from the fall that has come to the elbow, or due to a sharp contraction of the triceps. It is characterized by swelling with a bluish tinge, sharp pain during movement, deformity or droop of the hand.
2. Damage to the coronoid process - occurs due to a fall on the bent elbow. Complaints about puffiness, limited movements and pain.
3. Fracture of the proximal bone - the cause is a fall on the elbow in a bent state.
4. Fracture of the ulna or radius is due to a direct stroke. The main symptoms are edema, sharp pains, limited mobility.
5. Fracture of both forearm bones is characterized by displacement of broken bones and their rapprochement.

With fractures, it is extremely important to provide first aid to the victim. If the fracture is open, do not attempt to fix it yourself. It must be remembered that two joints are necessarily immobilized : wrist and elbow. To do this, you can apply a tire, without touching the side of the hand from which the bone protrudes.

The forearm is an important segment of the upper limb, providing high mobility of the hand and a variety of performed actions.