Human joints. Types of human joints

The human bone is so hard that it can withstand about 10,000 kilograms, but if the skeleton consisted of only one solid bone, our movement would be impossible. Nature solved this problem by simply dividing the skeleton into many bones and creating joints - the places where the bones intersect.

Human joints perform a rather important function. Thanks to them, the bones, teeth and cartilages of the body join together.

Types of human joints

They can be classified by functionality:

The joint, which does not allow movement, is known as synarthrosis. Seams of the skull and gompos (connecting the teeth with the skull) are examples of synarthrosis. The joints between the bones are called syndesmosis, between the cartilages - synchrodrosis, bone tissue - synthostosis. Synarthrosis is formed with the help of connective tissue.

Amphiarthrosis allows a slight movement of the joint bones. Examples of amphiarthrosis are intervertebral discs and pubic symphysis.

The third functional class is free-floating diarthroses. They have the highest range of motion. Examples: elbows, knees, shoulders and wrists. Almost always this synovial joints.

The joints of the human skeleton can also be classified according to their structure (by the material from which they consist):

Fibrous joints consist of hard collagen fibers. These include the seams of the skull and the joint, which connects the elbow and radius of the forearm together.

Cartilage joints of a man consist of a group of cartilages, which bind the bones to each other. Examples of such compounds are joints between the ribs and costal cartilage, as well as between the intervertebral discs.

The most common type - the synovial joint - is a fluid-filled space between the ends of the bones being bound. It is surrounded by a capsule of rigid tight connective tissue covered with a synovial membrane. The synovial membrane from which the capsule is made produces an oil synovial fluid, the function of which is to lubricate the joint, reducing friction and wear.

There are several classes of synovial joints, for example, ellipsoidal, block-shaped, saddle and globose.

Ellipsoidal joints interconnect smooth bones and allow them to slide past each other in any direction.

Block joints, for example, the elbow and knee joint of a man, restrict movement only in one direction so that the angle between the bones can be increased or decreased. Limited movement in the block joints provides more strength and strength to bones, muscles and ligaments.

Saddle joints, such as between the first metacarpal bone and the trapezoid bone, allow the bones to rotate 360 degrees.

The humerus and hip joint of a man are the only globular joints in the body. They have the most free range of motion, they are the only ones that can turn around their axis. However, the lack of globular joints is that the free range of motion makes them more susceptible to dislocation than the less mobile joints of a person. In these places, there are often fractures.

Some synovial types of human joints need to be considered separately.

Block joint

Block joints are a class of synovial joints. These are the ankles, the knee and elbow joint of a man. Usually a block-shaped joint is a bunch of two or more bones where they can only move along one axis to bend or straighten.

The simplest block-shaped joints in the body are interphalangeal, they are between the phalanges of the fingers and toes.

Because they have little body weight and mechanical strength, they consist of a simple synovial material with tiny additional ligaments for strengthening. Each bone is covered with a thin layer of smooth hyaline cartilage, designed to reduce friction in the joints. The bones are also surrounded by a capsule of a rigid fibrous connective tissue covered with a synovial membrane.

The structure of the human joint is always different. For example, the elbow joint is more complex, formed between the humerus, the radial and ulna bones of the forearm. The elbow is subjected to more heavy loads than the joints of the fingers and toes, therefore contains several strong additional ligaments and unique bone structures that strengthen its structure.

The ulnar and radial concomitant ligaments help keep the ulna and radius and strengthen the joints. Human legs also consist of several large block-shaped joints.

An elbow-like ankle joint is located between the large and small tibia in the lower leg and the talus in the leg. The branches of the tibia form a bony nest around the talus to limit movement of the foot along one axis. Four additional ligaments, including the deltoid, hold the bones together and strengthen the joint to maintain body weight.

Located between the thigh of the leg and the tibia and the tibia, the knee joint is the largest and most complex block-shaped joint in the human body.

The elbow joint and ankle joint, the anatomy of which is similar, are most often prone to osteoarthritis.

Ellipsoidal joint

The ellipsoidal joint, also known as flat, is the most common form of synovial joints. They are formed near bones having a smooth or almost smooth surface. These joints allow the bones to slide in any direction - up and down, left and right, diagonally.

Due to their structure, ellipsoidal joints are flexible, while their movement is limited (to prevent injury). Ellipsoidal joints are covered with a synovial membrane that produces a fluid serving as a joint lubricant.

Most ellipsoidal joints are in the appendicular skeleton between carpal bones of the wrist, between the carpal joints and the metacarpal bones of the hand, between the bones of the ankle.

Another group of ellipsoid joints lies between the facets of twenty-six vertebrae in the intervertebral joints. These joints allow us to bend, unbend and rotate the body, while maintaining the strength of the spine, which supports the weight of the body and protects the spinal cord.

Cleft joints

There is a separate kind of ellipsoid joints - condylar joint. It can be considered a transitional form from the block-like type of joint to ellipsoidal. From the block joint, the condylar differs greatly in the shape and size of the articulating surfaces, as a result of which it is possible to move around two axes. From the ellipsoid joint, condylar differs only in the number of joint heads.

Saddle joint

The saddle joint is a kind of synovial joint where one of the bones is formed as a saddle, and the other bone rests on it like a rider on a horse.

Saddle joints are more flexible than spherical or ellipsoidal joints.

The best example of a saddle joint in the body is the carpometacarpal joint of the thumb, which is formed between the bone of the trapezium and the first metacarpal bone. In this example, the trapezium forms a rounded saddle on which the first metacarpus is sitting. The carpus-metacarpal joint allows a person's thumb to be easily assisted with the other four fingers of the hand. The thumb, of course, is extremely important for us, since it allows our hand to firmly grasp objects and use many tools.

Spherical joint

Globular joints are a special class of synovial joints, which have the highest freedom of movement in the body due to their unique structure. The hip joint and humerus are the only spherical in the human body.

The two main components of the globular joint are: a bone with a ball-shaped head and a bone with a cup-like notch. Consider the shoulder joint. Human anatomy is so arranged that the globular head of the humerus (upper arm bone) fits into the articular cavity of the scapula. The articular cavity is a small and shallow notch, due to which the shoulder joint has the largest range of motion in the human body. It is surrounded by a ring of hyaline cartilages, which are flexible strengthening of the bone, while the muscles - the cuffs of the rotating device - hold the humerus inside the cavity.

The hip joint is somewhat less mobile than the shoulder, but is a stronger and more stable joint. Additional stability of the hip joint is necessary to support the weight of the human body on the legs, performing actions such as walking, running, etc.

In the hip joint, a rounded, almost spherical head of the femur (femur) fits snugly to the acetabulum, a deep recess in the hip bone. A sufficiently large number of rigid ligaments and strong muscles keep the femur head in place and resist the strongest stresses in the body. The acetabulum also prevents hip dislocations, limiting the movement of the bone within it.

Based on all of the above, you can make a small table. The structure of the human joint is not included in it. So, in the first column of the table the type of joint is indicated, in the second and third - examples and their location, respectively.

Human joints: a table

Type of joint	Examples of joints	Where are the
Block-like	Knee, elbow, ankle joint. The anatomy of some of them is given below.	Knee - between the femoral, tibia and patella; Elbow - between the shoulder, elbow and radius bone; Ankle - between the shin and foot.
Ellipsoidal	Intervertebral joints; Joints between phalanges of fingers.	Between the vertebrae faces; Between the phalanges of the toes and hands.
Globular	Hip and shoulder joint. The human anatomy pays special attention to this type of joint.	Between the femoral and pelvic bone; Between the humerus and the scapula.
Saddle-shaped	Wrist-metacarpal.	Between the bone of the trapezium and the first metacarpal bone.

To make it clearer what the human joints are, we will describe in more detail some of them.

Elbow joint

The ulnar joints of a person whose anatomy has already been mentioned require special attention.

The elbow joint is one of the most complex joints of the human body. It is formed between the distal end of the humerus (more precisely, its articular surfaces - the block and the condyle), the radial and blocklike cuts of the ulna, and also the head of the radius and its articular circumference. It consists at once of their three joints: the brachial, pleural and proximal radiolucent.

The pleural joint is located between the block-shaped notch of the ulna and the block (articular surface) of the humerus. This joint belongs to the block-shaped and is uniaxial.

The pelvic joint is formed between the humerus of the humerus and the head of the humerus. The movements in the joint are made around two axes.

The maximal radiolucent membrane connects the radial incision of the ulna and the articular circumference of the radial head. It is also uniaxial.

There are no lateral movements in the elbow joint. In general, it is considered a block-shaped joint with a helical shape of slip.

The largest of the upper body are elbows. The legs of a man also consist of joints, which you can not simply not tell.

Hip Joint

This joint is between the acetabulum on the pelvic bone and the femur (its head).

This head is covered with hyaline cartilage almost all over, except for the fossa. The acetabulum is also covered with cartilage, but only near the semilunar surface, the rest of it is covered with a synovial membrane.

To the hip joint are such ligament: ischial-femoral, ilio-femoral, pubic-femoral, circular zone, as well as a bundle of the head of the femur.

The ileum-femoral ligament originates in the inferior anterior iliac bone and terminates at the interstitial line. This ligament is involved in maintaining the trunk in an upright position.

The next ligament, ischial-femoral, begins in the ischium and is woven into the capsule of the hip joint itself.

A little higher, at the top of the pubic bone, begins the pubic-femoral ligament, which goes down to the capsule of the hip joint.

Inside the joint itself is a bundle of the head of the femur. It begins at the transverse ligament of the acetabulum and ends at the fossa of the head of the femur.

The circular zone is in the form of a loop: it is attached to the inferior anterior iliac bone and surrounds the neck of the femur.

The hip and shoulder joints are the only globular in the human body.

Knee-joint

This joint consists of three bones: the patella, the distal end of the femoral and the proximal end of the tibia.

The knee joint capsule is attached to the edges of the tibia, femur and patella. To the femur it is attached under the epicondyle. On the tibia is fixed along the edge of the joint surface, and to the patella the capsule is attached in such a way that the whole of its front surface is outside the joint.

The ligaments of this joint can be divided into two groups: extra-capsular and intracapsular. Also in the joint there are two lateral - tibial and peroneal collateral ligaments.

Ankle joint

It is formed with the help of the articular surface of the talus and the articular surfaces of the distal ends of the peroneal and tibial bones.

The joint capsule is practically all the way fixed to the edge of the articular cartilage and recedes from it only on the anterior surface of the talus bone. On the lateral surfaces of the joint are its ligaments.

The deltoid, or medial ligament, consists of several parts:

- posterior tibial-talant, located between the posterior edge of the medial malleolus and the posterior medial sections of the talus;

- anterior tibialis, located between the anterior edge of the medial malleolus and the posterior medial surface of the talus;

- Tibial-heel part, extending from the medial malleolus to the support of the talus;

- the tibial-navicular part, originating from the medial malleolus and ending at the rear surface of the scaphoid bone.

The next ligament, heel-fibular, extends from the outer surface of the lateral malleolus to the lateral surface of the cervix of the talus.

Not far from the previous one is the anterior talon-peroneal ligament - between the anterior edge of the lateral malleolus and the lateral surface of the cervix of the talus.

And the last, posterior talus-fibular ligament originates at the posterior edge of the lateral malleolus and ends at the lateral tubercle of the process of the talus bone.

In general, the ankle joint is an example of a block-shaped joint with a helical movement.

So, now we definitely have an idea of what the joints of a person are. Anatomy of the joints is more complicated than it seems, and you can see for yourself.