Where is the human forearm located?

Anatomy is a complex science, and it’s not easy to understand. Therefore, it is not surprising that people often confuse concepts such as shoulder, forearm, and girdle. This happens because most people misidentify the humerus. The shoulder is often considered the place between the neck and shoulder joint. And this is a very common mistake! But in fact, the shoulder is lower. Accordingly, the forearm is the part of the body that is located up to the elbow.

Anatomy

At the secondary level, schools begin to study a course in human anatomy. This is a very interesting and at the same time extensive section of biology, requiring high-quality acquisition of knowledge. Human anatomy is a science that examines the structure of the body, its functions and life activity as a whole.

A skeleton model or an anatomy atlas will tell you where a person’s forearm is located. Having carefully studied the name, location, types and purpose of bones, it is easy to understand the structure of the upper limb of a person - the hand.

The mobility of the skeleton is provided by muscles that are attached to the bones. By looking at the forearm, where there are many different types of muscle tissue, you can understand how the arm moves. Muscle contraction is facilitated by nerve impulses received by nerves located in the forearm.

Forearm: where is it located? Photo of a human skeleton

So, a little theory. An anatomical atlas or a skeleton model will help answer the question of where the human forearm is located. The bones of the forearm are one of the components of the human upper limb, playing an important role in the mobility of the arms. By carefully studying the image of the skeleton, it is easy to see where the shoulder and forearm are located.

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 it up.

Bones of the forearm

Part of the upper limb - the forearm, where there are two bones, has a fairly simple structure. It is composed of long tubular bones: the ulna and radius, each of which has its own structural features.

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

Consist of diaphysis, metaphysis and epiphysis. The diaphysis is the middle elongated part of the bone, having a cylindrical or triangular shape. Metaphysis is the space between the diaphysis and the epiphysis. The epiphysis is a thickened end necessary for connection with the joint.
On the epiphyses there is an articular surface covered with articular cartilage.
The epiphyses, depending on the location of the bone, can be proximal (upper) and distal (lower).
It is due to the metaphysis and the cartilaginous tissue located on it that tubular bones grow in length.
The epiphysis is spongy, and the diaphysis is compact.

The body of the ulna and radius is triangular in shape, meaning it has three surfaces. The front part of the bone faces forward, the back – back. The location of the third side differs between the radius and ulna.

Human hand bones: hand anatomy

The hand is one of the most anatomically complex areas of the hand. Conventionally, it can be divided into 3 functional zones:

The wrist is the distal part of the hand, formed by the carpal, metacarpal bones and phalanges. It includes 8 small spongy bones arranged in 2 rows. Their small size and soft articulation allow you to develop hand motor skills, honing the skills of more delicate work.
The metacarpus includes 5 short tubular bones connecting the wrist and fingers (one bone goes to each finger).
The fingers consist of phalanges of varying lengths. The thumb is formed by only two phalanges - proximal and distal; the remaining fingers also have a third phalanx - the middle one. The longer the fingers, the thinner and longer their phalanges will be.

The complex structure of the muscle fibers of the hand, with the assistance of the forearm muscles, provides a full range of finger movements. Visually, these muscles are difficult to train: unlike the biceps, triceps and other large groups of fibers, they do not protrude above the surface of the arm and do not increase in volume. Nevertheless, these muscles are easy to develop: it has been proven that with regular work related to fine motor skills, the fingers become more accurate and mobile, and with constant physical activity aimed exclusively at the forearm and shoulder, the hand muscles, on the contrary, atrophy.

Post Scriptum

The capabilities of human hands are enormous. Hundreds of nerve endings crowning the hands on the palms contribute to meticulously honed motor skills. However, more “rough” work is impossible without the participation of human hands, because strong muscles allow a person to lift and move weight, in some cases exceeding his own. With their help, a person can experience the world around him through one of the significant senses - touch. By developing these skills, you can significantly expand your own capabilities, but this process is impossible without knowledge and understanding of the anatomy of the hands.

The 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 side and is turned inward, like its edges.

The ulna is located on the outer part of the arm, 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 on the left, and the right one on the right. In other words, the ulna is located in the forearm on the little finger side.

The upper epiphysis of the ulna is thicker than the proximal epiphysis of the radius and is articulated with it using a trochlear notch, which is limited by two processes: the coronoid and the ulna. On the inner side 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 allows 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 an articular circle, and then passes into the wrist joint.

Anatomy of the human hand: basic components

Anatomically, the hand is the upper limb of the human musculoskeletal system. Like most parts of the body, it is formed by bone and muscle structures, ligaments, cartilage and tendons, as well as a network of blood capillaries and nerve fibers that provide tissue nutrition and impulse transmission, respectively.

For a more detailed study, the anatomy of the hand is usually classified into several key areas:

shoulder girdle;
shoulder;
forearm;
brush.

Each of these zones is sequentially connected to the others through complex joints. It is thanks to this that the arms can remain mobile, maintaining a wide trajectory of movement.

Structure and functions of the shoulder girdle

The shoulder girdle is the transition point from the torso to the upper limbs. It consists of two shoulder blades - right and left - and the same number of clavicles. Thanks to them, the position of the arms relative to the body is supported, as well as their movement along three different axes.

The shoulder blade is a flat, triangular bone located on the side of the back. Its relatively small thickness increases towards the lateral edge, where the articulation with the head of the humerus is located. The glenoid cavity, surrounded by tubercles, supports the humerus and allows for circular movements of the arms.

The scapula itself is slightly curved outward in the direction from the costal arches. On its outer side there is a key bone axis, on both sides of which powerful supraspinatus and infraspinatus muscle fibers are attached. The remaining muscle groups, as well as the ligaments that support the shoulder, are attached to the forward-facing coracoid process.

Another bone of the shoulder girdle - the collarbone - is tubular and has a slightly curved S-shape. It is located horizontally and slightly inclined downwards in the neck area. The collarbones serve as a connecting link between the sternum and shoulder blades, and also support the muscular frame of the shoulder girdle.

Anatomy of the bones and muscles of the shoulder

The shoulder is the upper part of the arm connected directly to the torso. At the elbow joint it passes into another area - the forearm. The shoulder consists of a large tubular bone, the shape of which varies depending on the zone: if closer to the shoulder blade, the section of the humerus has an almost perfectly rounded shape, then closer to the forearm it resembles more of a triangle with rounded corners.

The shoulder bears the majority of the physical load during work, so its muscular system is represented by strong, durable and powerful muscles that are easily amenable to physical development and improvement. The main part of the fibers surrounds the humerus, located parallel to the vertical axis. The skin in this area is relatively thin, so in physically developed, muscular people, the attachment points and the main bends of the muscles stand out noticeably. It is believed that the volume and relief of the forearm is directly proportional to a person’s strength, but this is not entirely correct: the basis of physical strength is not the size of the muscles, but their training, the ability to quickly contract and relax when exposed to high loads.

The functions of the shoulder are varied and include almost the full range of movements of the arm. To understand how this system functions, let's look at the anatomy of the key muscles that carry out certain actions.

Biceps

The biceps is the biceps brachii muscle, both heads of which tightly cover the upper part of the humerus. The two heads of the biceps - short and long - begin in the region of the shoulder joint, and approximately in the middle of the humerus they intertwine together, descending to a round eminence on the forearm.

By contracting and relaxing the muscle fibers that make up the biceps, a person can do the following:

move your palms up, rotate and straighten them;
flex your shoulder;
raise your arms forward and up, including with a load.

Triceps

The triceps, or triceps brachii muscle, consists of three heads of varying lengths that cover the elbow and part of the shoulder joints on the back of the arm. The medial and lateral fusiform heads of the triceps originate in the area of the humerus, and the long one is attached to the protrusion of the scapula. They, like the heads of the biceps, merge into one system in the lower part of the shoulder, forming a tendon attached to the olecranon process of the forearm bone.

The functions of the triceps are as follows:

straightening the arm parallel to the vertical axis of the body;
bringing the hand to a position near the body.

Brachialis muscle

This muscle is located directly under the biceps and comes to the surface of the muscular skeleton only at the point of attachment in the lower segment of the humerus. It is not as powerful as the biceps, but it also plays a key role in the physiological capabilities of the arm - thanks to its rhythmic contractions, a person can lift the ulna and flex the forearm.

Brachioradialis muscle

As the name suggests, this group of muscle fibers connects the shoulder and elbow joints, running along the entire length of the humerus. Its main function is to bend the arm at the elbow during contraction. You can notice this muscle on the surface of the ulnar fossa - its ridge protrudes especially clearly when lifting weights.

Anatomy of the forearm

The area of the upper limb starting at the elbow and ending at the wrist is called the forearm. It is formed by two bones of different diameters - the radius and the ulna. The section of the ulna has a triangular shape with a thickening at the upper end, at the point of articulation with the humerus. In front of the elbow joint there is a small trochlear notch that limits elbow extension, preventing unphysiological hyperextension of the muscles of the forearm and shoulder.

The radius, on the contrary, thickens downward, at the carpal joint. They are connected to the ulna bone movably, thanks to which the hand can rotate up to 180 degrees.

In its normal state, the forearm has a flattened shape with a noticeable expansion upward. This configuration is due to the specific location of the muscle tissue: closer to the elbow joint there are massive muscle bellies, which narrow and turn into tendons in the wrist area. Thanks to this, the volume of the lower part of the forearm can be used to judge how developed the bone structure of the hand is - thin carpal zones are characteristic of people with anatomically weak bones, and vice versa.

The muscles of the forearm are divided into 3 key groups. At the front are the fibers that control flexion and extension of the wrist and fingers, at the back are the extensor muscles, and at the side are the group responsible for the movement of the opposable thumb.

The structure of the radius

If the ulna is located medially, then the radius is not given a third: it is located on the inside of the arm, i.e., located distally. For example, the left forearm (where the ulna is located on the left) contains the radius on the right. In other words, the radius bone is located on the side of the thumb.

The third side of the radius is called the lateral side and 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 epiphysis contains the ulnar notch on the outer side for connection with the head of the ulna.

Muscular structure of the forearm

When diagnosing an isolated forearm fracture, a specialist will conduct an X-ray examination to check for dislocation or other injuries to the wrist and wrist joints. If the head of the ulna of the forearm is dislocated, it must be skillfully reset. This is necessary so that it can fuse with the rest of the bone without negative consequences. During rehabilitation, it is recommended to maintain the head of the elbow joint in the correct position. The extrinsic muscles serve as wrist extensors. They come in long and short. The back of the forearm consists of two layers of functional muscles. The set of muscles of the first layer is designed to perform extension movements of the wrist, hand, little finger and other fingers. The muscle block of the second layer is responsible for outward rotation of the arm. These muscles are used to allow the thumb and index finger to straighten.

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 to each other. The joints allow the radius to move around the ulna. The bone can move towards the inside or outside, with the wrist and elbow joints always acting together.

When performing a movement, the radius describes an arc of 140 degrees to the ulna. At the same time, the hand and shoulder are brought into motion, albeit slightly, which in total amounts to from 220 to 360 degrees of range of motion. It is the possibility of such rotation that allows a person to perform various movements with the upper limbs.

An important place in the connection of the bones of the forearm is occupied by 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 it does not restrict movement.

Where is the radius bone located in humans?

The bones of the forearm are connected by a connecting membrane. The forearm contains an anatomical axis passing through the radius, including its head and epiphysis. The main arteries supplying blood to the forearm area are the radial and ulnar arteries. Veins and lymphatic vessels provide the movement of venous blood and lymph to supply oxygen to the muscles and lymph nodes. The forearm performs an important function in human life. A hand experiencing discomfort for a long time reduces the quality of life. Do not delay going to the doctor to find out the cause, of which there can be many and each requires specific treatment.

Shoulder and forearm

The popular understanding of the location of the shoulder creates confusion in the early stages of studying human anatomy. What everyone is accustomed to considering as a shoulder is called in medicine the shoulder girdle, or shoulder girdle. Then where is the shoulder and where is the forearm? The shoulder is the section 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 is shaped like a ball. This is the head of the condyle of the humerus. The shoulder is connected to the ulna by the medial part, forming the block of the humerus. The coronoid and olecranon processes enter the trochlea anteriorly and posteriorly, respectively. Above the block there are pits into which the processes enter when flexing or extending the elbow.

Function

A Collis fracture is characterized by a special arrangement of broken bone elements, resembling an angle that allows the arm to straighten. A Collis fracture is easy to identify with the naked eye. This visual effect shows a clear displacement of the medial fragment. A Collis fracture may also involve various significant elbow joints or bones. Children's clubfoot can be corrected by systematically applying a cast to the surface of the forearm. When diagnosing fracture-dislocations, it is always important to ensure that no additional dislocations have occurred in adjacent joints. This is necessary because the possibility of damage to the joint capsule of the elbow joint should not be underestimated.

Forearm muscles

We have already figured out where a person’s forearm is. Let's take a closer look at exactly which muscles are involved in this segment of the upper limb. Depending on the movements performed, the muscles of the forearm can be divided into:

pronators - providing movement of the radius to the inside;
instep supports - allowing the radius to move outward;
flexors and extensors of the hand;
flexors and extensors of the fingers.

These muscle groups are grouped into two main categories depending on their position: anterior and posterior.

Anterior forearm muscles

The anterior muscles that move the forearm are where the radius turns inward. The group also includes flexor muscles. The superficial layer of muscle tissue of the anterior muscles begins from the medial part of the epicondyle of the shoulder. The deep muscle layers begin on the bones of the forearm and the membrane between them. The pronators are attached to the radius.

The muscle tissue closer to the humerus is more pronounced, and near the wrist it is represented mainly by tendons.

The superficial layer of the anterior muscles consists of:

Pronator teres - participates in flexion of the forearm, and also contributes to its inward rotation (palm turns down).
The brachioradialis muscle is involved in the process of supination and pronation, and in the flexion of the forearm. It originates from the humerus bone and is inserted into the distal radius.
Flexor carpi radialis - participates in flexion of the hand and partially rotates it inward.
Palmaris longus muscle - flexes the hand.
Flexor carpi ulnaris - is involved in moving the hand and bending it.
Superficial flexor digitorum - is involved in flexion of the middle phalanges of the fingers.

The deep layer of the anterior muscles is represented by the flexor pollicis longus, flexor digitorum profundus and pronator quadratus muscles. The forearm, where many muscles involved in the movement of the upper limb are located, determines the dexterity and variety of actions performed.

Posterior muscles of the forearm

The posterior group of muscles of the forearm consists of supinators and extensors. The superficial layer of muscle tissue consists of muscles:

Extensor carpi longus radialis - participates in flexion of the forearm at the elbow and extension of the wrist.
Extensor carpi brevis radialis – is involved in wrist extension and abduction.
Extensor fingers.
Extensor of the little finger.
Extensor carpi ulnaris - participates in abduction of the wrist towards the elbow and its extension.

The deep layer of the posterior muscles of the forearm is represented by the supinator, the long muscle (participates in the abduction of the thumb), the short and long extensor of the pollicis and the extensor of the index finger.

Types of states

Our shoulder joint is susceptible to injury. It does not tolerate mistreatment for long and responds with pain and dysfunction. The causes of pain in the shoulder joint are varied - heavy physical work, intense training in the gym, viral diseases. Shoulder pain can be caused by a bruise, dislocation or fracture. Constant pain in the left or right shoulder is a reason to consult a doctor. This will prevent the development of the disease and prevent it from becoming chronic. A person’s forearm is located between the elbow and wrist. It provides arm mobility while supporting weight. This organ consists of a large number of muscles that control the fingers and the hand as a whole. The flexor muscles of the forearm twist the arm down and forward, and the extensor muscles twist the arm backward.

Nerves of the forearm

The forearm, where many muscles are located, is also the site of passage of nerves. Let's look at the main nerves located in this area and their functions:

Musculocutaneous - its branches are located in the elbow joint, below it descends in the form of the cutaneous lateral nerve. Innervates the skin of the forearm.
Median - branches are located in the elbow joint and in the anterior muscles of the forearm. Innervates the joints of the hand and the muscles of the thumb.
Ulnar - located next to the ulnar artery, innervates the flexor carpi ulnaris. Below it is divided into branches that innervate the palm from the inside and outside.
Medial cutaneous - innervates the skin of the forearm, originates from the medial bundle.
Radial - the deep branch of this nerve innervates the extensor muscles of the forearm.

Ulna bone

The ulna bone is thickened at the end, and the trochlear notch is located on this thickening. It is designed to allow the humerus bone to articulate. The block-shaped tenderloin comes out in two segments:

rear, which is not very large in size
the anterior one, which is called the eternal process

From the radial edge on the coronoid process you can see a small notch at the articulation of the head of the radial bone. Just below is the tuberosity of the ulna.

The end at the bottom of the elbow bone has a thinner structure than the upper part and the whole thing is crowned by the head of the elbow bone, from where an awl-shaped process emerges. The bottom of the head has a flat structure, and the head itself is distinguished by an articular circumference.

Fractures of the forearm bones

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

Forearm fractures can be divided into several types:

Fracture of the olecranon 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 tint, sharp pain when moving, deformation or drooping of the arm.
Damage to the coronoid process - occurs due to a fall on a bent elbow. Complaints of swelling, limited movement and pain.
Fracture of the proximal part of the bone - the cause is a fall on the elbow in a bent state.
Fracture of the ulna or radius - occurs due to a direct blow. The main symptoms are swelling, sharp pain, and limited mobility.
Fracture of both bones of the forearm - characterized by displacement of the broken bones and their convergence.

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 set it yourself. It is necessary to remember that two joints are necessarily immobilized: the wrist and the elbow. To do this, you can apply a splint without touching the side of the arm from which the bone is protruding.

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

Fractures of the radius and ulna

The bones of the human forearm are often injured during a car accident or a fall during icy conditions. Among all visits to a traumatologist, the share of fractures in this part of the upper limb accounts for 20 to 30% . They are accompanied by complications and require careful adherence to the recommendations of doctors during treatment.

Causes

In most cases, the fracture occurs in the lower part of the forearm, where the bones are thinnest and most pliable. When diagnosing, doctors determine that the person fell with his hand outstretched, palm forward . In this case, the hand remains intact, and the wrist joint is occasionally damaged.

Other causes of injury:

osteoporosis with age-related changes;
lack of nutrition of calcium, phosphorus, and other minerals;
sedentary lifestyle;
natural aging and decreased bone density;
congenital pathologies.

Bones can weaken due to chronic diseases of the digestive system: vitamins and minerals necessary for cell regeneration are practically not absorbed in the intestines.

Varieties

There is a conditional classification , which depends on many factors:

depending on the cause of occurrence, there are traumatic and pathological ones associated with diseases of the human musculoskeletal system;
with displacement of bone fragments or without displacement;
closed and open with the formation of a painful wound on the forearm with protruding debris.

There are several main types of fractures based on their shape

transverse;
longitudinal;
helical;
splintered.

When an injury occurs, only one bone may be damaged. But in most cases, a fall on the elbow or wrist damages the integrity of the entire arm.

When fractures occur, the condyles that secure the muscles are often affected. The most painful form is associated with intra-articular injuries.

Depending on the location, fractures are:

Diaphysis. A person's mobility in the elbow is limited, swelling occurs, and severe pain occurs. The bone membrane contracts and the arm appears shortened.
The middle part of the radius or ulna . Accompanied by deformation, pronounced displacement of fragments, pain increases on both sides.
Heads or necks. Swelling occurs in the elbow area; it is painful to do simple flexion and extension movements.
Monteggia's fracture. At the same time, a fracture of the radius bone and a dislocation of its head occurs. The debris compresses the nerve endings, causing severe pain. The forearm visually becomes short, the hand springs when moving.
Galeazzi's fracture . The damage occurs to the lower part of the arm, and the head of the bone is dislocated. The palm seems to protrude forward, returning to its natural position when trying to straighten the joint. Formed after a fall on an extended arm.
Fracture in a typical location. More often diagnosed in elderly patients with osteoporosis. The main displacement occurs a few centimeters above the wrist joint. Swelling and hematoma appear due to pressure on the arteries.

MONTEGGIA & GALEAZZI DISLOCATION RADIUS FRACTURE ULNA DISLOCATION

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Any type of injury requires a comprehensive diagnosis. Using radiography, you can identify the presence of debris and displacement. If osteoporosis, pathological changes or chronic diseases are suspected, magnetic resonance imaging with contrast, blood tests, and consultation with an endocrinologist and traumatologist are recommended.

Symptoms

When a fracture occurs, severe pain, swelling, and impaired mobility of the hand occur.
Characteristic signs of fractures of any type:

severe pain;
the appearance of swelling on the inside or outside at the site of displacement;
the presence of an open injury on the skin, a wound with torn edges or bleeding due to an open fracture;
subcutaneous hematomas.

At the initial examination, the traumatologist checks the mobility of the fragments, the condition of the shoulder girdle and elbow bend, and, if necessary, reduces the dislocation. Based on the results of the x-ray and external symptoms, a decision is made on further therapy.