Where is the forearm of a 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 human anatomy. In order to understand, we will consider the structure and functions of the upper limb site on the forearm.

Anatomy

At the middle school level, they begin to study the course of human anatomy. This is a very interesting and at the same time an extensive section of biology, requiring the qualitative assimilation of knowledge. Human anatomy is a science that examines the structure of an organism, its functions and vital functions in general.

The model of the skeleton or the atlas of anatomy will tell you about where the human forearm is. Having carefully studied the name, location, types and purpose of the bones, it is easy to understand the structure of the upper limb of a person - the arm.

Skeleton mobility is provided by muscles that are attached to bones. Considering the forearm, where many different types of muscle tissue are located, you can understand how the arm moves. Muscle contraction is facilitated by nerve impulses, which are located in the forearm nerves.

Forearm: Where is it located? Photo of human skeleton

So, a little theory. The anatomical atlas or the model of the skeleton will help answer the question of where the human forearm is located. The bones of the forearm 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 you can guess 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 person. 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 two bones are located, has a fairly simple structure. It is made up of tubular long bones: ulnar and radial, each of which has its own structural features.

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

1. Consist of diaphysis, metaphysis and pineal gland. The diaphysis is the middle elongated part of the bone, having a cylindrical or trihedral shape. Metaphysis is the gap between the diaphysis and the pineal gland. The pineal gland is the thickened end needed to connect to the joint.
2. On the epiphyses is the articular surface, covered by articular cartilage.
3. Epiphyses, depending on the location of the bone, can be proximal (upper) and distal (lower).
4. It is due to 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 is trihedral, which means the presence of three surfaces. The front of the bone is facing forward, the rear is back. The location of the third side at the radius and ulna is different.

The structure of the ulna

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

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

The superior epiphysis of the ulna is thicker than the proximal epiphysis of the radius and articulated with it using a block notch, which is limited by two processes: coronoid and ulna. On the inside of the coronoid process there is a radial notch designed for the head of the radial bone. The connection in conjunction with the articular surface and cartilage forms the elbow joint, providing flexion and extension of the forearm.

The lower epiphysis, on the contrary, is thinner than the distal epiphysis of the radius and is connected to it using the articular circumference, and then passes into the wrist joint.

Radial bone structure

If the ulna is located medially, then the radial third is not given: it is located on the inside of the arm, that is, it is located distally. For example, the left forearm (where the ulna is located on the left) contains the radius in 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 superior epiphysis consists of a head with a small depression in the center, designed to connect to the condyle of the humerus. The distal pineal gland contains an elbow notch on the outside for connection with the head of the ulnar bone.

The connection of the bones of the forearm

An important role in the anatomy of the tubular bones of the forearm is played by the method of their connection with each other. The joints provide movement of the radius around the ulnar. The bone can move towards the inner or outer side, while the wrist and elbow joints always act together.

When a movement is made, the radius bone describes an ulnar bone in an arc of 140 degrees. At the same time, the brush and shoulder are given, albeit in a slight movement, which will total from 220 to 360 degrees of range of motion. It is the possibility of such rotation that allows a person to make various movements with his 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 radius and ulna and holds them in such a way that does not constrain movements.

Shoulder and forearm

The popular understanding of the location of the shoulder is confusing at the beginning of the study of human anatomy. What everyone is accustomed to taking as a shoulder is called a shoulder girdle, or shoulder girdle, in medicine. 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 connects to the bones of the forearm.

The shoulder is connected to the radius by the lateral part of the articular surface, which has the shape of a ball. This is the head of the condyle of the humerus. With the ulna, the shoulder is connected by the medial part, forming a block of the humerus. The coronoid and ulnar processes enter the block in front and behind, respectively. Above the block there are pits into which the processes enter during flexion or extension of the elbow.

Forearm muscles

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

• pronators - providing the movement of the radius in the inner side;
• arch support - allowing the radius to move outward;
• flexors and extensors of the brush;
• flexors and extensors of fingers.

These muscle groups are combined into two main categories, depending on their position: front and back.

Forearm muscles

The front muscles that move the forearm are where the radius is turned inward. The group also includes flexor muscles. The superficial layer of 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 closer to the humerus is more pronounced, and near the wrist composition is represented mainly by tendons.

The surface layer of the front muscles are:

1. The pronator is round - participates in bending the forearm, and also contributes to its rotation inward (palm turns down).
2. Brachioradial muscle - participates in the process of supination and pronation, in flexion of the forearm. It originates from the bone of the shoulder and is fixed in the distal radius of the radius.
3. Radial wrist flexor - participates in the flexion of the hand and partially rotates it inward.
4. Palmar long muscle - bends the hand.
5. Elbow flexor of the wrist - participates in bringing the brush into motion and bends it.
6. Superficial flexor of the fingers - is involved in bending the middle phalanges of the fingers.

The deep layer of the front 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 agility and variety of actions performed.

Back muscles of a forearm

The back group of muscles of the forearm are arch support and extensors. The surface layer of muscle tissue consists of muscles:

1. Radial long extensor of the hand - is involved in flexion of the forearm in the elbow and extension of the wrist.
2. Radial short extensor of the hand - is involved in the extension of the wrist and its abduction.
3. Extensor fingers.
4. The extensor of the little finger.
5. Elbow extensor of the hand - is involved in the abduction of the wrist towards the elbow and its extension.

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

Forearm nerves

The forearm, where many muscles are located, is also the place of passage of nerves. Consider the main nerves located in this area, and their functions:

• Muscular-cutaneous - its branches are located in the elbow joint, below it descends in the form of a cutaneous lateral nerve. Innervates skin of a forearm.
• Median - the branches are located in the elbow joint and in the front muscles of the forearm. Innervates the joints of the hand, the muscles of the thumb.
• Elbow - located next to the ulnar artery, innervates the ulnar flexor of the wrist. Below it is divided into branches innervating the palm from the inside and outside.
• Medial cutaneous - innervates the skin of the forearm, originates from the medial bundle.
• Radiation - the deep branch of this nerve innervates the extensor muscles of the forearm.

Forearm fractures

The bones of the forearm are quite thin, as a result of which they break easily enough even with minor injuries.

Fractures of the forearm can be divided into several types:

1. Fracture of the ulnar process - occurs due to a fall on the elbow, or due to a sharp contraction of the triceps. It is characterized by swelling with a bluish tinge, sharp pain during movements, deformation or drooping of the arm.
2. Damage to the coronoid process - occurs due to falling on a bent elbow. Complaints of swelling, limited movement 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 - occurs due to a direct impact. The main symptoms are swelling, sharp pains, limitation of mobility.
5. Fracture of both bones of the forearm - characterized by the displacement of broken bones and their rapprochement.

In case of fractures, it is extremely important to provide first aid to the victim. If the fracture is open, you should not try to correct it yourself. It must be remembered that two joints are necessarily immobilized: the wrist and the elbow. To do this, you can lay a splint without touching the side of the arm from which the bone protrudes.

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