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Ligament human anatomy. Joints, ligaments, fibrous (fibrous) joints. Own syndesmoses of the pelvis complement its walls

Numerous in the human body bone joints it is advisable to present in the form of a classification. In accordance with this classification, there are two main types of bone joints - continuous and discontinuous, each of which, in turn, is divided into several groups (Gaivoronsky I.V., Nichiporuk G.I., 2005).

Types of bone joints

Continuous connections (synarthrosis, synarthrosis)

Discontinuous connections (diarthrosis, diarthrosis; synovial joints or joints, articulationes synoviales)

I. Fibrous connections (articulationes librosae): ligaments (ligamenta); membranes (membranae); fontanelles (fonticuli); seams (suturae); stabbing (gomphosis)

II. Cartilaginous joints (articulationes cartilagineae): joints using hyaline cartilage (temporary); connections with fibrous cartilage (permanent)

III. Connections using bone tissue (synostosis)

According to the axes of rotation and the shape of the articular surfaces:

By the number of articular surfaces: simple (art. simplex); complex (art. composite)

By simultaneous joint function: combined (art. combinatoria)

It should be noted that the relief of the bones often reflects a specific type of connection. Continuous joints on the bones are characterized by tuberosities, ridges, lines, pits and roughness, while discontinuous joints are characterized by smooth articular surfaces of various shapes.

Continuous connections of bones

There are three groups of continuous joints of bones - fibrous, cartilaginous and bone.

I. Fibrous joints of bones, or connections with the help of connective tissue, - syndesmoses. These include ligaments, membranes, fontanelles, sutures, and impactions.

Ligaments are connections with the help of connective tissue, having the form of bundles of collagen and elastic fibers. According to their structure, ligaments with a predominance of collagen fibers are called fibrous, and ligaments containing predominantly elastic fibers are called elastic. Unlike fibrous, elastic ligaments are able to shorten and return to their original shape after the load is stopped.

Along the length of the fibers, the ligaments can be long (posterior and anterior longitudinal ligaments of the spinal column, supraspinous ligament), connecting several bones over a large distance, and short, connecting adjacent bones (interspinous, transverse ligaments and most ligaments of limb bones).

In relation to the joint capsule, intra-articular and extra-articular ligaments are distinguished. The latter are considered as extracapsular and capsular. Ligaments as an independent type of connection of bones can perform various functions:

retaining or fixing (sacral tuberous ligament, sacrospinous, interspinous, intertransverse ligaments, etc.);
the role of the soft skeleton, as they are the place of origin and attachment of muscles (most of the ligaments of the limbs, ligaments of the spinal column, etc.);
shaping, when they, together with the bones, form arches or openings for the passage of blood vessels and nerves (upper transverse ligament of the scapula, ligaments of the pelvis, etc.).

Membranes are connections with the help of connective tissue, having the form of an interosseous membrane, which, unlike ligaments, fills the vast gaps between the bones. Connective tissue fibers in the composition of membranes, mainly collagen, are located in a direction that does not prevent movement. Their role is in many ways similar to ligaments. They also hold the bones relative to each other (intercostal membranes, interosseous membranes of the forearm and lower leg), serve as the site of the beginning of muscles (these membranes) and form openings for the passage of blood vessels and nerves (obturator membrane).

Fontanelles are connective tissue formations with a large amount of intermediate substance and sparsely located collagen fibers. Fontanels create conditions for the displacement of the bones of the skull during childbirth and contribute to the intensive growth of bones after birth. The anterior fontanelle reaches the largest size (30 x 25 mm). It closes in the second year of life. The posterior fontanel measures 10 x 10 mm and disappears completely by the end of the second month after birth. Even smaller sizes are paired wedge-shaped and mastoid fontanelles. They overgrow before birth or in the first two weeks after birth. Fontanelles are eliminated due to the growth of the bones of the skull and the formation of suture connective tissue between them.

Sutures are thin layers of connective tissue located between the bones of the skull, containing a large amount of collagen fibers. The shape of the seams are jagged, scaly and flat, they serve as a growth zone for the bones of the skull and have a shock-absorbing effect during movements, protecting the brain, organs of vision, hearing and balance from damage.

Impaction - connection of teeth with cells of the alveolar processes of the jaws with the help of dense connective tissue, which has a special name - periodontium. Although this is a very strong connection, it also has pronounced cushioning properties when the tooth is loaded. The periodontal thickness is 0.14-0.28 mm. It consists of collagen and elastic fibers, oriented throughout perpendicularly from the walls of the alveoli to the root of the tooth. Loose connective tissue lies between the fibers, containing a large number of vessels and nerve fibers. With a strong compression of the jaws due to the pressure of the antagonist tooth, the periodontium is strongly compressed, and the tooth sinks into the cell up to 0.2 mm.

With age, the number of elastic fibers decreases, and under load, the periodontium is damaged, its blood supply and innervation are disturbed, the teeth loosen and fall out.

II. Cartilage joints of bones- synchondroses. These compounds are represented by hyaline or fibrous cartilage. Comparing these cartilages with each other, it can be noted that hyaline cartilage is more elastic, but less durable. With the help of hyaline cartilage, the metaphyses and epiphyses of the tubular bones and individual parts of the pelvic bone are connected. Fibrous cartilage mainly consists of collagen fibers, therefore it is more durable and less elastic. This cartilage connects the vertebral bodies. The strength of cartilaginous joints also increases due to the fact that the periosteum from one bone passes to another without interruption. In the area of the cartilage, it turns into the perichondrium, which, in turn, is firmly fused with the cartilage and is reinforced by ligaments.

According to the duration of existence, synchondrosis can be permanent and temporary, that is, existing until a certain age, and then replaced by bone tissue. Under normal physiological conditions, metaepiphyseal cartilages, cartilages between separate parts of flat bones, cartilage between the main part of the occipital and the body of the sphenoid bones are temporary. These compounds are mainly represented by hyaline cartilage. The cartilages that form the intervertebral discs are called permanent; cartilage located between the bones of the base of the skull (sphenoid-stony and sphenoid-occipital), and cartilage between the 1st rib and the sternum. These compounds are represented mainly by fibrous cartilage.

The main purpose of synchondroses is to mitigate shocks and stresses under heavy loads on the bone (depreciation) and to ensure a strong connection of the bones. Cartilaginous joints at the same time have great mobility. The range of motion depends on the thickness of the cartilage layer: the larger it is, the greater the range of motion. As an example, we can cite a variety of movements in the spinal column: forward, backward, sideways, twisting, springy movements, which are especially developed in gymnasts, acrobats and swimmers.

III. Connections with bone tissue- synostoses. These are the strongest connections from the group of continuous ones, but they have completely lost their elasticity and shock-absorbing properties. Under normal conditions, temporary synchondrosis undergoes synostosis. In some diseases (Bekhterev's disease, osteochondrosis, etc.), ossification can occur not only in all synchondrosis, but also in all syndesmoses.

Discontinuous bone connections

Discontinuous connections are joints or synovial connections. A joint is a discontinuous cavitary connection formed by articulating articular surfaces covered with cartilage, enclosed in an articular bag (capsule), which contains synovial fluid.

The joint must necessarily include three main elements: the articular surface, covered with cartilage; joint capsule; joint cavity.

1. Articular surfaces are areas of bone covered with articular cartilage. In long tubular bones, they are located on the epiphyses, in short ones - on the heads and bases, in flat ones - on the processes and body. The forms of the articular surfaces are strictly determined: more often there is a head on one bone, a fossa on the other, less often they are flat. The articular surfaces on the articulating bones must correspond in shape to each other, i.e., be congruent. More often, the articular surfaces are lined with hyaline (vitreous) cartilage. Fibrous cartilage covers, for example, the articular surfaces of the temporomandibular joint. The thickness of the cartilage on the articular surfaces is 0.2-0.5 cm, and in the articular fossa it is thicker along the edge, and on the articular head - in the center.

In the deep layers, the cartilage is calcified, firmly connected with the bone. This layer is called humiliated, or impregnated with calcium carbonate. Chondrocytes (cartilage cells) in this layer are surrounded by connective tissue fibers located perpendicular to the surface, i.e., in rows or columns. They are adapted to resist pressure forces on the articular surface. The superficial layers are dominated by connective tissue fibers in the form of arcs beginning and ending in the deep layers of the cartilage. These fibers are oriented parallel to the cartilage surface. In addition, there is a large amount of intermediate substance in this layer, so the surface of the cartilage is smooth, as if polished. The surface layer of cartilage is adapted to resist frictional forces (tangential forces). With age, the cartilage undergoes agglomeration, its thickness decreases, it becomes less smooth.

The role of articular cartilage is that it smooths out the irregularities and roughness of the articular surface of the bone, giving it greater congruence. Due to its elasticity, it softens shocks and shocks, therefore, in joints that carry a large load, the articular cartilage is thicker.

2. Articular bag- this is a hermetic capsule surrounding the articular cavity, growing along the edge of the articular surfaces or at a slight distance from them. It consists of an outer (fibrous) membrane and an inner (synovial) membrane. The fibrous membrane, in turn, consists of two layers of dense connective tissue (outer longitudinal and inner circular), in which blood vessels are located. It is strengthened by extra-articular ligaments, which form local thickenings and are located in places of greatest load. The ligaments are usually closely associated with the capsule and can only be separated artificially. Ligaments isolated from the joint capsule are rare, for example, the lateral tibial and peroneal tibia. In stiff joints, the fibrous membrane is thickened. In mobile joints, it is thin, slightly stretched, and in some places it is so thin that the synovial membrane even protrudes outward. This is how synovial ecversions (synovial bags) are formed, usually located under the tendons.

The synovial membrane faces the joint cavity, is abundantly supplied with blood, and is lined from the inside with synoviocytes capable of secreting synovial fluid. The synovial membrane covers the inside of the entire joint cavity, passes to the bones and intra-articular ligaments. Only surfaces represented by cartilage remain free from it. The synovial membrane is smooth, shiny, can form numerous processes - villi. Sometimes these villi break off and, as foreign bodies, fall on the interarticular surfaces, causing short-term pain and preventing movement. This condition is called "articular mouse". The synovial membrane can lie directly on the fibrous membrane or be separated from it by a subsynovial layer or a fatty layer, therefore, fibrous, areolar and fatty synovial membranes are distinguished.

The synovial fluid in terms of composition and nature of formation is a transudate - an effusion of blood plasma and lymph from the capillaries adjacent to the synovial membrane. In the joint cavity, this fluid mixes with the detritus of sloughing synoviocyte cells and abraded cartilage. In addition, the composition of the synovial fluid includes mucin, mucopolysaccharides and hyaluronic acid, which give it viscosity. The amount of fluid depends on the size of the joint and ranges from 5 mm3 to 5 cm3. Synovial fluid performs the following functions:

lubricates the articular surfaces (reduces friction during movements, increases sliding);
connects the articular surfaces, holds them relative to each other;
softens the load;
nourishes articular cartilage;
participates in metabolism.

3. Joint cavity- this is a hermetically sealed space, limited by the articular surfaces and the capsule, filled with synovial fluid. It is possible to single out the joint cavity on an intact joint only conditionally, since there is no void between the articular surfaces and the capsule, it is filled with synovial fluid. The shape and volume of the cavity depend on the shape of the articular surfaces and the structure of the capsule. In sedentary joints, it is small, in highly mobile ones it is large and can have eversion that extends between bones, muscles and tendons. The pressure in the joint cavity is negative. When the capsule is damaged, air enters the cavity, and the articular surfaces diverge.

In addition to the main elements, auxiliary elements can be found in the joints, which provide optimal joint function. These are intraarticular ligaments and cartilages, articular lips, synovial folds, sesamoid bones and synovial bags.

Intra-articular ligaments are fibrous ligaments covered with a synovial membrane that connect the articular surfaces at the knee joint, at the rib head joint, and at the hip joint. They hold the articular surfaces relative to each other. This function is especially clearly seen in the example of the cruciate ligaments of the knee joint. When they break, a “drawer” symptom is observed, when, when bent at the knee joint, the lower leg is displaced in relation to the thigh anteriorly and posteriorly by 2-3 cm. The ligament of the femoral head serves as a conductor of the vessels that feed the articular head.
Intra-articular cartilage- These are fibrous cartilages located between the articular surfaces in the form of plates. The plate that completely divides the joint into two “floors” is called the articular disc (discus articularis). In this case, two separated cavities are formed, as, for example, in the temporomandibular joint. If the joint cavity is only partially divided by cartilage plates, i.e., the plates are crescent-shaped and fused with the capsule at the edges, these are the menisci (menisci), which are presented in the knee joint. Intra-articular cartilages ensure the congruence of the articular surfaces, thereby increasing the range of motion and their diversity, help mitigate shocks, and reduce pressure on the underlying articular surfaces.
articular lip- this is a fibrous cartilage of an annular shape, complementing the articular fossa along the edge; while one edge of the lip is fused with the joint capsule, and the other goes into the articular surface. The articular lip occurs in two joints: the shoulder and the hip (labrum glenoidale, labrum acetabulare). It increases the area of the articular surface, makes it deeper, thereby limiting the range of motion.
Synovial folds (plicae synoviales)- These are connective tissue formations rich in vessels, covered with a synovial membrane. If fatty tissue accumulates inside them, then fatty folds are formed. The folds fill the free spaces of the joint cavity, which is large. Contributing to the reduction of the joint cavity, the folds indirectly increase the adhesion of the articulating surfaces and thereby increase the range of motion.
Sesamoid bones (ossa sesamoidea)- these are intercalary bones closely connected with the joint capsule and the tendons of the muscles surrounding the joint. One of their surfaces is covered with hyaline cartilage and faces the joint cavity. Intercalated bones help to reduce the cavity of the joint and indirectly increase the range of motion in it. They are also blocks for the tendons of the muscles acting on the joint. The largest sesamoid bone is the patella. Small sesamoid bones are often found in the joints of the hand, foot (in the interphalangeal, carpometacarpal joint of the 1st finger, etc.).
Synovial bags (bursae synoviales)- These are small cavities lined with a synovial membrane, often communicating with the joint cavity. Their value is from 0.5 to 5 cm3. A large number of them are found in the joints of the limbs. Synovial fluid accumulates inside them, which lubricates adjacent tendons.

Movements in the joints can only be carried out around three axes of rotation:

frontal (axis corresponding to the frontal plane dividing the body into anterior and posterior surfaces);
sagittal (axis corresponding to the sagittal plane dividing the body into right and left halves);
vertical, or its own axis.

For the upper limb, the vertical axis passes through the center of the head of the humerus, the head of the condyle of the humerus, the head of the radius and ulna. For the lower limb - in a straight line connecting the anterior superior iliac spine, the inner edge of the patella and the thumb.

The articular surface of one of the articulating bones, having the shape of a head, can be represented as a ball, ellipse, saddle, cylinder or block. Each of these surfaces corresponds to the articular fossa. It should be noted that the articular surface can be formed by several bones, which together give it a certain shape (for example, the articular surface formed by the bones of the proximal row of the wrist).

1 - ellipsoid; 2 - saddle; 3 - spherical; 4 - block-shaped; 5 - flat

Movements in the joints around the axes of rotation are determined by the geometric shape of the articular surface. For example, a cylinder and a block only rotate about one axis; ellipse, oval, saddle - around two axes; a sphere or flat surface around three.

The number and possible types of movements around the existing axes of rotation are presented in the tables. So, two types of movements are noted around the frontal axis (flexion and extension); around the sagittal axis there are also two types of movements (adduction and abduction); when moving from one axis to another, another movement occurs (circular, or conical); around the vertical axis - one movement (rotation), but it can have subspecies: rotation inward or outward (pronation or supination).

Axes of rotation, number and types of possible movements

The maximum number of possible types of movements in the joints, depending on the number of axes of rotation and the shape of the articular surface

Joint axis	The shape of the articular surface	Realizable axes of rotation	Number of movements	Types of movements
uniaxial	blocky	Frontal	2	Flexion, extension
uniaxial	Rotary (cylindrical)	vertical	1	Rotation
Biaxial	Ellipse, saddle	Sagittal and frontal	5	Flexion, extension, adduction, abduction, circular motion
Biaxial	Condylar	Front and vertical	3	Flexion, extension, rotation
multi-axis	spherical, flat	Frontal, sagittal and vertical	6	Flexion, extension, adduction, abduction, circular motion, rotation

Thus, there are only 6 types of movements. Additional movements are also possible, such as sliding, springy (removal and convergence of articular surfaces during compression and tension) and twisting. These movements do not belong to individual joints, but to a group of combined ones, for example, intervertebral ones.

Based on the classification of the joints, it is necessary to characterize each individual group.

I. Classification of joints according to the axes of rotation and the shape of the articular surfaces:

Uniaxial joints- these are joints in which movements are made only around any one axis. In practice, such an axis is either frontal or vertical. If the axis is frontal, then in these joints movements are made in the form of flexion and extension. If the axis is vertical, then only one movement is possible - rotation. Representatives of uniaxial joints in the form of articular surfaces are: cylindrical (articulatio trochoidea) (rotational) and block-shaped (ginglymus). Cylindrical joints carry out movements around the vertical axis, i.e., rotate. Examples of such joints are: median atlantoaxial joint, proximal and distal radioulnar joints.

The trochlear joint is similar to a cylindrical joint, only it is not located vertically, but horizontally and has a scallop on the articular head, and a notch on the articular fossa. Due to the scallop and notch, displacement of the articular surfaces to the sides is impossible. The capsule at such joints is free in front and behind and is always strengthened by lateral ligaments that do not interfere with movement. Block joints always work around the frontal axis. An example is the interphalangeal joints.

A variation of the block joint is the cochlear (articulatio cochlearis), or helical, joint, in which the notch and scallop are beveled, have a helical course. An example of a cochlear joint is the humeroulnar joint, which also works around the frontal axis. Thus, uniaxial joints have one or two types of movement.

Biaxial joints- joints that work around two of the three available axes of rotation. So, if movements are made around the frontal and sagittal axes, then such joints realize 5 types of movements: flexion, extension, adduction, abduction and circular motion. According to the shape of the articular surfaces, these joints are ellipsoid or saddle-shaped (articulatio ellipsoidea, articulatio sellaris). Examples of ellipsoid joints: atlantooccipital and radiocarpal; saddle: carpometacarpal joint of the 1st finger.

If the movements are carried out around the frontal and vertical axes, then it is possible to realize only three types of movements - flexion, extension and rotation. In shape, these are condylar joints (articulatio bicondyllaris), for example, the knee and temporomandibular joints.

Condylar joints are a transitional form between uniaxial and biaxial joints. The main axis of rotation in them is the frontal. Unlike uniaxial joints, they have a greater difference in the areas of the articular surfaces, and in connection with this, the range of motion increases.

Multiaxial joints- these are joints in which movements are carried out around all three axes of rotation. They make the maximum possible number of movements - 6 types. In shape, these are spherical joints (articulatio spheroidea), for example, the shoulder. A variety of the spherical joint is cup-shaped (articulatio cotylica), or nut-shaped (articulatio enarthrosis), for example, the hip joint. It is characterized by a deep articular fossa, a strong capsule reinforced with ligaments, and the range of motion in it is less. If the surface of the ball has a very large radius of curvature, then it approaches a flat surface. A joint with such a surface is called flat (articulatio plana). Flat joints are characterized by a small difference in the areas of the articular surfaces, strong ligaments, movements in them are sharply limited or absent at all (for example, in the sacroiliac joint). In this regard, these joints are called inactive (amphiarthrosis).

II. Classification of joints according to the number of articular surfaces.

Simple joint (articulatio simplex)- a joint that has only two articular surfaces, each of which can be formed by one or more bones. For example, the articular surfaces of the interphalangeal joints are formed by only two bones, and one of the articular surfaces in the wrist joint is formed by three bones of the proximal row of the wrist.

Composite joint (articulatio composita)- this is a joint, in one capsule of which there are several articular surfaces, therefore, several simple joints that can function both together and separately. An example of a complex joint is the elbow joint, which has 6 separate articular surfaces, forming 3 simple joints: humeroradial, humeroulnar, proximal radioulnar. Some authors also include the knee joint as a complex joint. Given the articular surfaces on the menisci and the patella, they distinguish such simple joints as the femoral-meniscal, menisco-tibial and femoral-patellar. We consider the knee joint to be simple, since the menisci and the patella are auxiliary elements.

III. Classification of joints according to simultaneous joint function.

Combined joints (articulatio combinatoria)- these are joints that are anatomically separated, that is, located in different joint capsules, but functioning only together. For example, the temporomandibular joint, proximal and distal radioulnar joints. It should be emphasized that in true combined joints it is impossible to make a movement in only one of them, for example, only in one temporomandibular joint. With a combination of joints with different forms of articular surfaces, movements are realized along a joint that has a smaller number of axes of rotation.

Factors that determine the range of motion in the joints.

The main factor is the difference in the areas of articulating articular surfaces. Of all the joints, the largest difference in the areas of the articular surfaces is in the shoulder joint (the area of the head of the humerus is 6 times the area of the articular cavity on the shoulder blade), therefore, the largest range of motion is in the shoulder joint. In the sacroiliac joint, the articular surfaces are equal in area, so there is practically no movement in it.
The presence of auxiliary elements. For example, menisci and discs, by increasing the congruence of the articular surfaces, increase the range of motion. Articular lips, increasing the area of the articular surface, contribute to the limitation of movements. Intra-articular ligaments limit movement only in a certain direction (cruciate ligaments of the knee joint do not prevent flexion, but counteract excessive extension).
joint combination. In combined joints, movements are determined by the joint that has a smaller number of axes of rotation. Although many joints, based on the shape of the articular surfaces, are able to perform a greater range of motion, they are limited due to the combination. For example, according to the shape of the articular surfaces, the lateral atlantoaxial joints are flat, but as a result of combination with the median atlantoaxial joint, they work as rotational ones. The same applies to the joints of the ribs, hand, foot, etc.
condition of the joint capsule. With a thin, elastic capsule, movements are made in a larger volume. Even the uneven thickness of the capsule in the same joint affects its work. For example, in the temporomandibular joint, the capsule is thinner in front than behind and on the side, so the greatest mobility in it is anteriorly.
Strengthening the joint capsule with ligaments. Ligaments have a retarding and guiding effect, since collagen fibers have not only high strength, but also low extensibility. In the hip joint, the iliofemoral ligament prevents extension and rotation of the limb inward, the pubic-femoral ligament - abduction and rotation outward. The most powerful ligaments are in the sacroiliac joint, so there is practically no movement in it.
Muscles surrounding the joint. Possessing a constant tone, they fasten, bring together and fix the articulating bones. The muscle traction force is up to 10 kg per 1 cm2 of the muscle diameter. If you remove the muscles, leave the ligaments and the capsule, then the range of motion increases dramatically. In addition to the direct inhibitory effect on the movements in the joints, the muscles also have an indirect effect - through the ligaments from which they begin. Muscles during their contraction make the ligaments stubborn, elastic.
synovial fluid. It has a cohesive effect and lubricates the articular surfaces. With arthrosis-arthritis, when the secretion of synovial fluid is disturbed, pain, crunch appear in the joints, and the range of motion decreases.
Screw deflection. It is present only in the shoulder-elbow joint and has an inhibitory effect on movement.
Atmosphere pressure. It contributes to the contact of the articular surfaces with a force of 1 kg per 1 cm2, has a uniform tightening effect, therefore, moderately restricts movement.
Condition of the skin and subcutaneous adipose tissue. In obese people, the range of motion is always less due to the abundant subcutaneous fatty tissue. In slender, fit, athletes, movements are made in a larger volume. With skin diseases, when elasticity is lost, movements are sharply reduced, and often after severe burns, wounds, contractures are formed, which also significantly impede movement.

To determine the range of motion in the joints, there are several methods. Traumatologists determine it with a goniometer. Each joint has its own starting positions. The starting position for the shoulder joint is the position of the arm hanging freely along the body. For the elbow joint - full extension (180°). Pronation and supination are determined with the elbow joint bent at a right angle and with the hand placed in the sagittal plane.

In anatomical studies, the value of the angle of mobility can be calculated from the difference in the arcs of rotation on each of the articular articular surfaces. The value of the angle of mobility depends on a number of factors: gender, age, degree of training, individual characteristics.

Joint diseases
IN AND. Mazurov

The connection of the bones of the lower extremities is represented by ligaments and joints. In contrast to the interosseous joints of the shoulder girdle and arms, the ligaments and joints of the legs and pelvic girdle of a person are less mobile. This feature is explained by evolutionary functionality: the pelvis and legs of Homo erectus have a supporting function, while the arms are designed to perform fine and precise movements and provide grip on objects.

As part of the skeleton of the lower limb, as well as the upper, there are: a belt (pelvic belt), with the help of which it is fixed to the skeleton of the body, and the free part of the lower limb (leg), which consists of three main segments (thigh, lower leg and foot), movably connected to each other.

The lower limbs were formed in humans as organs of support and movement. Because of this, they have a very strong and practically immovable connection of the bones of the pelvic girdle with the skeleton of the body, as well as various limitations of mobility in the main joints on the leg.

When walking (the main type of locomotion in humans), there is a regular alternation of phases of support on two legs and phases of support on one of the legs. When pushing off and moving one leg forward, the main segments of the leg (thigh, lower leg and foot) are bent at the main joints.

In the other (supporting) leg, on the contrary, they are extended and held in a straightened state in relation to the foot. By virtue of this connection, the lower limbs are adapted mainly to flexion and extension movements, as well as to the shock absorption that occurs when walking.

This article presents photos, names and descriptions of the joints and ligaments of the human legs.

Anatomy of the pelvic girdle of the human lower limbs: joints and ligaments

The joints of the bones of the pelvic girdle of the lower extremities are distinguished by great strength and extremely low mobility.

The sacroiliac joint (articulatio sacroiliaca) is formed by the ear-shaped surface of the sacrum and the ear-shaped surface of the ilium. In shape, this joint of the lower extremity girdle is flat (amphiarthrosis). Movement in the joint is practically absent.

The articular capsule is attached along the edge of the articular surfaces, and it is strengthened by ligaments:

Anterior sacroiliac ligament ( lig. sacroiliacum anterius) - passes along the anterior surface of the joint capsule;
Posterior sacroiliac ligament ( lig. sacroiliac posterius) - passes along the posterior surface of the joint capsule;
Interosseous sacroiliac ligament ( lig. sacroiliacum interos-seum) - fills the depression between the tuberosities of the sacrum and the ilium. This is one of the most powerful ligaments in the human body.

In addition, the ilium is strengthened relative to the spinal column by the iliolumbar ligament (lig. iliolumbale) of the lower limb, stretched from the transverse process of the V lumbar vertebra to the iliac crest.

pubic symphysis ( symphysis pubica) - a cartilaginous joint between two pelvic bones, in which a narrow cavity is located.

The pubic symphysis is strengthened by ligaments:

superior pubic ligament ( lig. pubicum superius) - runs along the upper edge of the cartilage between the pubic tubercles;
inferior pubic ligament ( lig. pubicum inferius) - runs along the lower edge of the cartilage and rounds the subpubic angle.

Own syndesmoses of the pelvis complement its walls:

obturator membrane ( membrana obturatoria) - closes the hole of the same name. At the upper edge of the obturator foramen in the region of the obturator sulcus, the obturator canal (canalis obturatorius) remains for the passage of the neurovascular bundle;
sacrospinous ligament ( lig. sacrospinale) - starts from the apex and posterior surface of the ischial spine and ends at the edge of the sacrum. This connection of the belt of the lower limb limits the large sciatic notch, forming a large sciatic foramen (foramen ischiadicum majus);
sacrotuberous ligament ( lig. sacrotuberale) - starts from the medial surface of the ischial tuberosity and is attached to the edges of the sacrum and coccyx. Both of the above ligaments, together with the lesser sciatic notch, form the lesser sciatic foramen (foramen ischiadicum minus).

hip joint ( articulatio coxae) belt of the lower human bone is formed by the acetabulum (acetabulum) of the pelvic bone, namely its lunate surface, which is complemented by the acetabular lip (labrum acetabuli), and the head of the femur. This connection of the girdle of the lower limb is spherical; its glenoid fossa is deep and almost completely covers the head of the femur.

The joint capsule is attached along the bony edge of the acetabulum of the pelvic bone; on the thigh in front - along the intertrochanteric line, behind - about 1 cm before reaching the intertrochanteric crest. Thus, the femoral neck is inside the joint capsule and its fractures will be intra-articular.

The hip joint of the lower limb girdle has a dense joint capsule and powerful ligaments that limit the range of motion of the lower limb, while increasing its supporting properties:

iliofemoral ligament ( lig. iliofemorale) starts from the anterior inferior iliac spine, descends along the anterior surface of the joint capsule and attaches to the intertrochanteric line. This is one of the most powerful ligaments of the human body, which prevents excessive hip extension, adduction and internal rotation. Its deepest beams pass into a circular zone;
Circular zone ( zona orbicularis) lies in the thickness of the articular capsule, is attached to the ilium to the spina iliaca anterior inferior and covers the femoral neck with a loop; the ligament holds the head of the femur in the joint;
ischiofemoral ligament ( lig. ischiofemorale) starts from the body of the ischium, goes up to the trochanteric fossa of the thigh. The ligament prevents excessive hip adduction and internal rotation;
Pubic-femoral ligament ( lig. pubofemorale) starts from the superior branch of the pubic bone; attached to the lesser trochanter and intertrochanteric line. Prevents excessive hip abduction and outward rotation.

In the cavity of the hip joint of the skeleton of the lower limbs there is a ligament of the femoral head (lig. capitis femoris), it begins in the depth of the acetabulum and is attached to the fossa of the femoral head. The ligament is surrounded by a synovial membrane. Inside the ligament, an artery passes to the head of the femur. This ligament also acts as a shock absorber in the joint.

This connection of the human lower extremities is multiaxial, movements are possible around three axes, but the range of motion is limited, which is affected by the deep position of the articular head in the articular fossa and the presence of strong ligaments that strengthen the joint capsule and limit movement. Movements in the joint: around the sagittal axis - abduction and adduction, around the transverse axis - flexion and extension, around the vertical axis - inward rotation (pronation) and outward rotation (supination); possible circular motion - circumduction.

Anatomy of the free part of the lower limb: features of ligaments, joints and arches

Knee-joint ( articulation genus) formed by the condyles (medial and lateral) of the femur and the upper articular surface on similar condyles of the tibia; the sesamoid bone, the patella, also participates in its formation.

The shape of the knee joint is condylar, biaxial. The main movements in it are flexion and extension (around the transverse axis); however, slight rotational movements (around the vertical axis) are possible in the flexed position.

The joint capsule is free; attached, retreating 2-3 cm from the edge of the articular surfaces on the thigh and tibia.

The synovial membrane in front of the joint forms pterygoid folds ( plicae alares) - These are paired formations containing adipose tissue that play the role of shock absorbers.

The subpatellar synovial fold (plica synovialis infrapatellaris) goes as a continuation of the pterygoid folds to the intercondylar fossa of the thigh. In front, the subpatellar fat body protrudes into the synovial fold of the joint.

The bones in this connection of the free part of the lower limb are held in an articular state by powerful ligaments, which at the same time limit the lateral displacement of the bones, as well as excessive flexion and extension.

In the joint cavity of the human leg, called the articulatio genus, there are powerful cruciate ligaments that serve as the main limiter for the extension of the lower leg. Between the lateral condyle of the thigh and the anterior intercondylar field, the anterior cruciate ligament (lig. cruciatum anterius) is stretched; between the medial condyle of the thigh and the posterior intercondylar field is the posterior cruciate ligament (lig. cruciatum posterius). They are covered with a synovial membrane, which isolates them from the joint cavity.

tibial collateral ligament ( lig. collaterale tibiale) - starts from the medial epicondyle of the thigh, descends in the form of a wide plate to the medial edge of the tibia. The ligament is fused with the capsule and medial meniscus.

peroneal collateral ligament ( lig. collateral fibulare) The human leg runs between the lateral epicondyle of the femur and the head of the fibula.

In front of the joint is the tendon m. quadriceps femoris, which contains the patella. Most of the tendon fibers run from the top of the patella to the tuberosity of the tibia, and they are isolated as a ligament of the patella (lig. Patellae). It is separated from the joint capsule of the free part of the lower limb by loose fatty tissue.

Tendon plates extend from both sides of the patella, which are attached to the condyles of the tibia: lateral and medial supporting ligaments of the patella (retinaculum patellae lat. et med.); they hold the patella in its position during movement in the joint.

Behind the joint capsule is strengthened by an oblique popliteal ligament (lig. Popliteum obliquum) - a continuation of the tendon fibers passing through the muscles here, which go from the medial condyle of the tibia laterally upward and are woven into the joint capsule.

Arcuate popliteal ligament ( lig. popliteum arcuatum) of the joint of the limb starts from the lateral epicondyle-femur, passes to the middle of the oblique ligament and is woven into the joint capsule.

In the cavity of the knee joint there is a medial meniscus (meniscus medialis) of a crescent shape and a lateral meniscus (meniscus lateralis) of an oval shape, which subdivide the joint cavity into two floors. Both menisci are fused with the joint capsule, their inner ends are thin, the outer edges are thicker.

The menisci increase the congruence of the surfaces of articulating bones. The menisci are connected anteriorly by the transverse ligament of the knee. In addition, the menisci are attached to the condylar eminence of the tibia and to the femoral condyles by the anterior and posterior meniscofemoral ligaments.

When the synovial membrane passes from the femur to the menisci and from the meniscus to the tibia, pockets of the synovial membrane are formed.

As shown in the photo, the knee joint of the human leg is surrounded by synovial bags:

These bags facilitate friction between muscle tendons passing near the joint and other anatomical formations:

Suprapatellar bag ( bursa suprapatellaris) located above the patella, located between the quadriceps femoris and the femur: usually communicates with the joint cavity;
Subcutaneous prepatellar bursa ( bursa subcutanea prepatellaris) located in front of the patella; there are also subfascial and dry bags;
Subcutaneous subpatellar bursa ( bursa subcutanea infrapatellaris) located below the patella; p deep subpatellar bag (bursa infrapatellaris profunda) is located below the patella, between its ligament and the tibia; communicates with the joint cavity.

The interosseous edges of the bones of the lower leg are connected by the interosseous membrane of the lower leg (membrana interossea cruris).

tibiofibular joint ( articulatio tibiofibularis) formed by the peroneal articular surface of the tibia and the articular surface of the head of the fibula; there is practically no movement in it.

There is a tibiofibular syndesmosis in the distal tibia.

The foot is a single biomechanical formation that performs the function of a support for the body both when standing, and when walking and other types of locomotion.

The joints of the bones of the free part of the lower limb play a major role in the formation of the foot as that part of the leg, which is designed to perform two important functions:

Serve as a support for the whole body
Perform repulsion while walking (and while running).

Therefore, the foot is characterized by the development of a powerful ligamentous apparatus and a significant limitation of mobility in the joints. The complex of bones of the tarsus and metatarsus, interconnected by means of inactive joints and strong syndesmoses, forms the solid base of the foot.

Moreover, the foot has an arched structure, resulting in the midfoot being raised off the ground. This provides shock absorption when walking and running.

The talus plays a key role in connecting the foot to the lower leg and the entire leg. It transmits the action of the body's gravity to the supporting calcaneus and at the same time provides flexion and extension of the entire foot - its main movements when walking.

The talus simultaneously participates in the formation of three joints:

Ankle (nadtalar),
The joint between the talus and calcaneus (subtalar)
The joint between the talus, calcaneus, and scaphoid bones (talocalcaneal-navicular).

The combined mobility in these three joints ensures the installation of the foot both when standing and when walking, which directly affects the formation of an individual human gait.

Ankle joint ( articulatio talocruralis) formed by the fibula (the articular surface of the lateral malleolus), the tibia (the lower articular surface of the tibia and the articular surface of the medial malleolus), and the talus (the articular surfaces of the talus block). The joint is blocky in shape.

The articular capsule is thin, fairly loose, attached along the edge of the articular surfaces.

The joint is strengthened by well-defined lateral ligaments. The anatomy of the lateral ligaments of the leg is as follows. On the medial side is the medial (deltoid) ligament (lig. mediate (deltoideum).

It starts from the medial malleolus and ends expanding; has four processes that go to os naviculare, os calcaneus, anterior and posterior edges of os talus.

Three ligaments stand out from the lateral side of the joint: anterior talofibular ligament (lig. talofibulare anterius), which is located in front of the joint; calcaneal fibular ligament (lig. calcaneofibulare) goes from the lateral ankle to the lateral side of the calcaneus; posterior talofibular ligament (lig. talofibulare posterius) runs horizontally behind the joint.

The main movement in the joint is performed around the transverse axis passing through the block of the talus: flexion of the foot (or plantar flexion) - movement of its plantar surface down; extension of the foot (or dorsiflexion) - the movement of its back surface upwards. When the foot is in plantar flexion, slight abduction and adduction are possible.

subtalar joint ( articulatio subtalaris) formed by the talus (posterior calcaneal articular surface) and calcaneus (posterior talar articular surface). The articular capsule is free, reinforced with ligaments: lateral talocalcaneal and medial talocalcaneal.

talocalcaneo-navicular joint ( articulatio talocalcaneonavicularis) formed by the talus (middle and anterior calcaneal articular surfaces), calcaneus (middle and anterior talus articular surfaces), head of the talus (navicular articular surface) and articular surface of the navicular bone. The articular capsule in the anatomy of this leg joint is attached along the edge of the articular surfaces; it is strengthened by ligaments: plantar calcaneal-navicular and ram-navicular.

The subtalar and talocalcaneal-navicular joints form a complex combined articulation on the foot, in which very limited movements of the foot are possible during plantar flexion: its supination in combination with adduction and pronation with abduction.

In the sinus of the tarsus ( sinus tarsi) a powerful interosseous talocalcaneal ligament (lig. talocalcaneum interosseum) passes between the talus and calcaneus.

Pay attention to the photo - this ligament of the leg firmly connects the bones to each other:

Calcaneocuboid joint ( articulatio calcaneocuboidea) formed by the cuboid articular surface of the calcaneus and the articular surface of the cuboid bone. The joint capsule is attached along the edge of the articular surfaces, strengthened by ligaments: dorsal calcaneocuboid, plantar calcaneocuboid and long plantar. Mobility is extremely limited.

For reasons of surgical practice, the talocalcaneal-navicular joint and the calcaneocuboid joint are combined into a transverse tarsal joint (Chopard's joint). The distal part of the foot is amputated along the line of this joint. The bones of the tarsus in the area of this joint are firmly connected by a bifurcated ligament (lig. bifurcatum), consisting of lig. calcaneocuboideum and lig. calcaneonaviculare. Only by crossing these ligaments is it possible to amputate the distal part of the foot.

wedge-shaped joint ( articulatio cuneonavilcularis) formed by the navicular bone, sphenoid bones and cuboid bone; extremely immobile joint. Between the sphenoid bones there are also inactive flat intersphenoid joints.

Tartarus-metatarsal joints ( articulationes tarsometatarles) . In the anatomy of the lower extremities, three joints are distinguished: between the medial sphenoid bone and the I metatarsal bone, between the intermediate and lateral sphenoid bones of the II and III metatarsal bones; between the cuboid bone and IV-V metatarsal bones. The joints are strengthened by numerous ligaments and are extremely inactive.

For practical purposes, the three tarsometatarsal joints are combined into one Lisfranc joint, along the line of which the distal part of the foot is also amputated. The key ligament in this joint is the interosseous ligament (lig. interosseum), stretched deep between the medial sphenoid bone and the base of the second metatarsal bone.

Intertarsal joints ( articulationes intermetatarsales) formed by the articular surfaces of the bases of the metatarsal bones and the bones of the tarsus, reinforced with powerful ligaments, extremely inactive.

Metatarsophalangeal joints ( articulationes metatarsophalangeae) formed by the heads of the metatarsal bones and the bases of the proximal phalanges. Articular capsules are attached along the edge of the articular surfaces, strengthened by collateral and plantar ligaments. The joints are immobile.

The complex of bones of the tarsus and metatarsus, interconnected by means of inactive joints and strong syndesmoses, stands out as a solid base of the foot.

interphalangeal joints ( articulationes interphalangeae) blocky in shape. Articular capsules are free, reinforced with collateral ligaments. Flexion and extension of the fingers are possible.

Being interconnected, the bones of the foot form an arch, facing upwards with a bulge. The main points of support on the foot are the calcaneal tubercle and the heads of the metatarsal bones. The arches are formed as a result of the formation of an angle between the body of the calcaneus and the calcaneal tuber, and are held due to the powerful ligamentous apparatus on the foot and the work of the muscles of the lower leg and foot. The arched structure of the foot provides its elasticity and shock absorption when walking. There are longitudinal and transverse arches of the foot.

There are five longitudinal arches of the foot, which corresponds to the number of metatarsal bones. The vaulted arches start from the calcaneal tuber and diverge forward along radii convex upwards through the bones of the tarsus and each of the five metatarsal bones to its head.

The longest and highest is the second longitudinal arch, corresponding to the II metatarsal bone. Medial arches (I-III) - spring; they bear the brunt of walking. The lateral arches (IV-V) are considered as supporting ones, ensuring the stability of the foot during movements.

The transverse arch of the foot connects the arches of the longitudinal arches at the level of the heads of the metatarsal bones. Normally, the foot rests in the anterior section mainly on the heads of the I and V metatarsal bones. The heads of the II, III, IV metatarsal bones rise in the form of a vault above the plane of the foot support.

This article is about links. About the ligaments that are part of our skeleton, and about the vocal cords. You will learn what ligaments are and understand their purpose in our body.

Ligaments of the skeleton

A ligament is a band of connective tissue that connects bones to each other, supports or strengthens a joint, and prevents it from moving in the wrong direction. It is a vital part of the structure of the entire skeleton. There are ligaments in every joint. Ligaments do not serve to connect muscles to bones, this function is performed by tendons.

The ligaments are elastic, which allows them to stretch with the movements of the joints. Athletes do specially designed stretching exercises that allow their joints to become more flexible. People with extraordinary flexibility have very elastic ligaments that allow their joints to bend and stretch more than the average person.

The maintenance of many internal organs, including the uterus, bladder, liver, and diaphragm, are also functions of the ligaments. They help shape and support the breasts.

Under prolonged tension, the ligaments lengthen. For this reason, in the event of a dislocated joint, it must be returned to its normal position as soon as possible to avoid long-term damage to the ligaments.

Unlike most structures in the human body, ligaments cannot heal themselves. There are cases when, after injuries, the joint that was damaged continues to deteriorate. He does not respond to treatments such as braces and physical therapy. In this case, it is necessary to resort to reconstruction of the ligaments.

Vocal cords

Ligaments consist of connective and muscle tissue, which increases their elasticity. There is a space between the vocal cords called the glottis. With the pressure on them of the air coming out of the lungs, the ligaments come together. They stretch and begin to wobble. The result is a voice. These are not all functions of the vocal cords. They also prevent foreign bodies from entering the lungs and bronchi.

What are joints?

A joint is a structure that provides a movable articulation of the bones of mammalian vertebrates. The human skeleton contains more than 200 bones. Some bones are firmly connected to each other (for example, the bones of the cranial vault). More than 100 bones can move relative to each other due to the presence of ligaments, etc. There are various classifications of joints.

A joint is a movable connection of bones that allows them to move relative to each other. The nature of the movement depends on the shape of the joint.

They are usually classified according to the way they move, for example, according to the direction of displacement: uniaxial, biaxial and triaxial. Condylar joints (knee, elbow) allow movement in one plane. INspherical joints (shoulder joint) are moving around three axes and circular motion. In the saddle joints (carpometacarpal joint of the thumb), the articulating surfaces of the bones are saddle-shaped. Articular surfaces of flat joints (intercarpal joints) slide over each other without making angular and rotational movements.

Joint structure:

The joints form strong end sections of bones (articular heads) that can withstand heavy loads, covered with cartilage, the shape of which determines the direction of movement of the joint. The articular heads are covered by a dense formation of connective tissue - the articular capsule, which is lined from the inside with a mucous membrane that secretes a viscous fluid that ensures the sliding of the joint. Thanks to this fluid, friction between the bones is softened and their wear is reduced. Inside the capsule, ligaments hold the joints together. Thanks to the ligaments, the joints do not collapse and they are provided with proper movement.

What are ligaments?

Ligaments, in the correct position, hold the bones that form the joint. With a heavy load, a rupture of the ligaments occurs (in this case, a knee ligament rupture occurred).

Ligaments are dense connective tissue strands and plates that connect the bones of the skeleton or individual organs. Located mainly in the area of the joints, they strengthen them, limit or direct movements in the joints. The movement of the joints is provided by muscles, the contraction of which is transmitted to the bones by inelastic tendons. Meanwhile, the ligaments directly located in the joints provide stability to the joint. Ligaments can stretch slightly, giving the joint elasticity, which protects it from dislocation. Important functions are performed by ligaments located outside the joints, such as the ligaments of the abdominal organs. They support the internal organs, and during digestion they provide the necessary elasticity of the stomach and the mobility of the intestines, as well as the mobility of the uterus during the period, etc.

Ligament structure:

Ligaments are connective tissue and are mainly composed of proteins two kinds. Most of the mass is made up of collagen protein with a long molecule resembling a chain, so collagen fibers are strong. They are permeated with a "network" of elastin. The necessary mobility and flexibility of the joints is provided by ligaments, consisting of thin separate layers, located cruciformly relative to each other. For this reason, the joints can be stable in all planes and at the same time quite flexible, relative to each other can only be movable bundles interconnected by fibers of layers of elastin.

Ligaments get old:

With age, the elasticity of the ligaments gradually decreases. With each stretching of the ligaments, additional collagen is formed in them, and the ligaments harden. Of course, as a result of this, the stability of the joint is improved, but its elasticity is reduced.

Link substitutes:

Today, when ligaments are torn or overstressed, it is not difficult for surgeons to replace them with glass or carbon fiber prostheses. These ligaments are fixed during the operation in small holes made in the bone.

ON A NOTE:

Joints are not always formed by two bones. The elbow joint consists of the humerus, ulna and radius bones. Knee - from the femur, tibia and fibula. And the joints of the wrist and tarsus are generally formed by a large number of bones.

The study of ligaments on a large material convinced us that they develop in the presence of a tensile force from those parts of the mesenchyme that have at least two points of attachment. These attachment points can be movable or fixed. In the first case, the ligaments can keep the articulating bones from moving; in the second case, they act as a support for other formations: muscles, fascia, blood vessels, nerves, etc.

Wherever ligaments appear, in all cases they "work" in tension. But if in the ligaments of individual bones a tensile force arises due to lateral pressure on them, then the formation of a ligament between two bones is due to the divergence of the ends of the bones. This discrepancy (removal from each other) of the articulated bones or their sections occurs as a result of an atypical or abnormal range of motion (which happens more often) or traction (stretching) along the axis of the limb (the latter - only when the contracting function of the muscles is insufficient). As a result of slipping of one bone relative to another, forward, backward, or to the side, ligaments arise that keep the bones from directional slipping. This is also evidenced by the fact that the most powerful ligaments are developed on the side where the role of the muscles as a strengthening apparatus is either completely absent or weakened. All these provisions have been confirmed in our works and are clearly illustrated by numerous examples.

Thus, the anterior cruciate ligament of the knee joint is formed under the action of the tensile force that occurs when the hip slips back. The fact is that when the limb is maximally extended in the knee joint, the articular surface of the tibia is tilted back at an angle of 7-8 °. Knowing the subject's body weight, the force that displaces the femur can be calculated using the formula:

where F is the force that displaces the thigh back with the lower limb extended at the knee joint; P - body weight; a - angle of inclination of the plane of the articular surface of the upper end of the tibia relative to the horizontal plane.

Under the action of this force, collagen bundles opposing it are formed in the connective tissue surrounding the joint. As this force builds up, the opposing structures become more powerful and eventually can be isolated as the anterior cruciate ligament.

The posterior cruciate ligament in humans and many mammals is well defined. However, frogs, lizards, turtles have only one ligament in the knee joint. An analysis of the position of the bones and the ratio of their articular surfaces in amphibians and reptiles showed that in all phases of movement in the knee joint, the plane of the articular surface of the upper end of the tibia is tilted backward. Therefore, the hip under the weight of the body can only move back. The tibia prevents the hip from moving forward and downward.

For the first time in the phylogenetic series, two cruciate ligaments in the knee joint appear in birds. The relationship of the articular surfaces of the knee joint of birds is such that the femur in various phases of statics and dynamics can slide both forward and backward. This was the reason for the formation of two cruciate ligaments.

Lateral and other ligaments are also formed under the action of tensile forces that occur when the bones are displaced. This can be well seen in the experiments of V.I. Saveliev. He took a corpse, marked the articular ends of the bones in the knee joint with contrasting points, made the usual movements and measured the distance between pre-selected points on x-rays. It turned out that in different phases of the movement this distance changes. The unequal removal of the same point on the thigh from the tibia is especially pronounced on the lateral side. This led to the fact that the lateral (collateral) peroneal ligament consists of powerful collagen bundles of different orientations. In some cases, there are even two (superficial and deep) ligaments that have different attachment points. When the limb is bent at the knee joint, the superficial part of the ligament is stretched; at this time, its deep part is relaxed. When the limb is extended at the knee joint, the superficial part of the ligament relaxes, and the deep part stretches as much as possible.

The functional role of the ligaments in the ankle joint is very clear. The ligaments of this joint are formed only from the medial and lateral sides and are completely absent in the direction of movement, where almost all muscles are concentrated. From this it follows that in the direction of movement, the strengthening of the joint is carried out by the muscles, and the ligaments prevent the bones from moving to the side. In experiments it was shown that when resting on the foot in the position of the main stance (the tibia is perpendicular to the sole), the ligaments are not tense, they even sag slightly. If the muscles are removed, then the foot hangs on the ligaments under the influence of its own weight, and the gap of the ankle joint increases by 1-2 mm. During flexion and extension, as it approaches the border of the articular surface of the talus block, the ligaments straighten out. At the moment when the edge of the articular surface of the tibia reaches the anterior or posterior border of the articular surface of the block (which happens on the verge of the range of active and passive movements), the ligaments are completely straightened, the edges of the articular surfaces on the side of the movement are in close contact. The continuation of movement in this direction takes place already in the zone of the range of passive movements. In this case, the ligaments are strained so much that the tortuosity of the collagen bundles of the ligament disappears, and the articular surfaces on the opposite side diverge. Approximately the same data were obtained in the experiment on the knee and elbow joints.

Analysis of the material confirms that ligaments are formed not as limiters within the range of active movements, but as a strengthening apparatus that prevents displacement of bones at a certain position of the limbs (or body parts) and outside the range of active movements. In this respect such comparisons are interesting. In humans, the lateral tibial ligament of the knee joint is 2-3 times larger than the lateral fibular ligament. It also differs in mechanical properties. So, the lateral peroneal ligament can withstand a load of up to 25 kg on a tensile machine, and the lateral tibial ligament - up to 45-50 kg. Of course, such strengthening of the tibial ligament is caused by a greater load falling on it with the valgus (X-shaped) position of the bones observed in humans. Some animals (horse, bull, pig, etc.), for example, do not have such a pronounced valgus position of the bones in the knee joint. They have lateral ligaments of the knee joint in size and severity do not differ from each other.

But if the ligaments do not prevent movement within the range of active movements, then they do not remain indifferent to passive movements and become tense at the moment they reach their maximum range. Two conclusions follow from this.

1. Any purposeful movement will help strengthen the ligamentous apparatus of the joint. At the same time, movements of a small volume, but with a significant power load, will more effectively strengthen the ligamentous apparatus; large movements will increase the range of ligament extensibility, which contributes to the expansion of the range of passive movements and more frequent damage to the ligaments.
2. Transcendental movements (beyond the boundaries of possible passive ones) can lead to damage to the ligaments - up to their rupture. That is why ligament rupture occurs, as a rule, when the muscles are turned off (for details, see Chapter III).

The ligaments of the joints are part of the fibrous capsule and are sometimes artificially isolated from it. The fibrous capsule of the joint is even less involved in purposeful (active) movements. This is evidenced by experiments to determine the range of motion with a removed fibrous capsule on the ankle, knee and elbow joints, carried out in our laboratory.

Given the origin of the ligaments, their functional role, it is advisable to classify them depending on the location and relationship to the fibrous capsule of the joints. The classification of syndesmoses proposed by us (shell adhesions, which include ligaments) is shown in fig. 4.

So, all ligaments perform one function: they keep the organs or their individual parts from divergence (displacement). However, according to localization, the ligaments of the musculoskeletal system can be divided into: ligaments of one bone, ligaments of joints, interosseous membranes, sutures.

Ligaments of one bone . They usually occur as a result of muscle attachment. If the place of attachment of the muscle has a linear extent and there are bone protrusions along this length, then a connective tissue cord (ligament) is formed between the bone protrusions, which performs the function of a tendon. These are the poupartova ligament (lig.inguinale), ligaments of the scapula, arcuate ligaments of the diaphragm, etc. During muscle contraction, these ligaments tense and “work” in tension, acting as tendons.

Ligaments of joints . This category includes ligaments that hold bones near each other (interosseous membranes, sutures) or help strengthen joints (ligaments of joints, synchondroses), as well as supporting ligaments (retinaculum flexorum, extensorum, peroneorum) on the limbs, etc.

Interosseous membranes . In the body, they are widely represented: the yellow ligament between the arches of the vertebrae, the interosseous membrane of the forearm, the interosseous membrane of the lower leg, the intercostal membranes, the integumentary membrane in the atlantooccipital joint, and many others. All these connective tissue membranes are formed between bones remote from each other, but functionally interconnected, as a result of which such connections arise between them that allow significant displacements, but keep the bones within the allowable divergence. The function of these membranes is reflected in their internal structure. These are flat formations consisting of unidirectional large collagen bundles - usually oblique.

Ligaments of joints and cartilaginous joints (synchondrosis) . The most numerous group of ligaments. Strengthening of joints of this kind is provided mainly by muscles. The ligamentous apparatus enhances the strength of the joints. There is no fundamental difference between the ligaments of the joints and synchondroses, but due to the different volume of movement in these joints, the ligaments of the joints are more diverse in location and shape.

As noted earlier, the ligaments of the joints are for the most part derivatives of the fibrous capsule of the joints or (more correctly) derivatives of the mesenchyme surrounding the joint. If the joint is surrounded on all sides by muscles and they strengthen the joint, then the ligaments are absent or poorly developed. The function of an additional strengthening structure of the joint is performed by a fibrous capsule. In some places, it becomes thinner to loose connective tissue formations, and in some places it is enhanced by growing collagen fibers - then a ligament can be distinguished in it. Such, for example, is the fibrous capsule of the shoulder joint with a single and poorly contoured cora-shoulder ligament. But if the muscle attachment sites are far from the joint, then the muscles are not able to effectively provide its strengthening - especially with a significant load. Under these conditions, the fibrous capsule grows significantly, but always unevenly, since the load on the joint is also uneven. In such cases, several powerful ligaments can be distinguished in the composition of the capsule itself. A good example is the capsule of the hip joint, in which the iliac-femoral, ischiofemoral, pubic-femoral and other ligaments are isolated.

In cases where the edges of the articular surfaces are uneven or located at considerable distances from the contacting (rubbing) surfaces of the joint, connective tissue strands are formed between these bone protrusions, which subsequently transform into powerful ligaments. They are removed from the fibrous capsule of the joint (lateral, cruciate and other ligaments). Such an arrangement of ligaments is possible only in joints with an extensive range of motion and a significant growth of the articular ends of the bones. In this regard, we recommend distinguishing the capsular ligaments that go as part of the fibrous capsule; extra-capsular - taken out of the capsule; intracapsular. The last ligaments are often called intra-articular, which, from our point of view, is incorrect. The fact is that the so-called intra-articular ligaments are not located in the joint cavity, but between the fibrous and synovial capsules of the joint. Therefore, it is advisable to call them intracapsular. For example, the ligament of the femoral head and the cruciate ligaments of the knee joint, although located in the joint cavity, are enveloped on all sides by a thin synovial capsule and are thus fenced off from the joint cavity.

The group under consideration includes the so-called retaining ligaments (lig.retinaculaeperonealae). The origin of these ligaments is different: they are the seals of the fascia of the muscles near the joints. Muscle fasciae always have points or lines of fusion with the periosteum. The significance of these adhesions is that the fasciae keep the muscles from moving at the time of contraction. The adhesions of the fascia with the periosteum throughout the limb act as intermuscular partitions, and near the joints - in the form of retaining ligaments. Thanks to these ligaments, the tendons of the contracting muscles during flexion or extension movements do not move away from the joints.

The classification of the ligamentous apparatus proposed by us not only facilitates the understanding of the functional purpose of the ligaments, but also aims doctors and trainers at the correct planning of physical activity regimes - in order to strengthen the ligaments, prevent osteoarticular injuries by using different training modes of active and passive movements.

Synovial capsule of the joint . This element is essential. The synovial capsule consists of loose fibrous connective tissue rich in fatty accumulations. From the inside, the membrane is lined with synovial cells of the endothelial type. The shell is widely represented by blood and lymphatic vessels, nerve elements. Synovial cells are highly reactive, providing intensive production of synovial fluid. Probably, the vessels of the synovial membrane also take part in this process. As a result of the high reactivity of synovial cells, their increased growth occurs, which leads to the appearance of synovial villi. In those places where the synovial membrane is slightly displaced and not squeezed (free space), fat cells accumulate in it. In some places it is so significant that synovial-fatty folds are formed. These folds, like synovial villi, are outgrowths of the synovial membrane and increase the total surface of the synovial bag of the joint.

In subsequent sections of the book - based mainly on the author's own research, as well as special sources - ideas about the structure, properties and functions of the joints and their components will be expanded and specified.