Continuous bone connections are called. Bone joints
2. Types of bone joints. Continuous connections, their classification, structure.
There are two main types of bone joints: continuousand discontinuous,or joints... Continuous connections are found in all lower vertebrates and at the embryonic stages of development in higher ones. When the latter form the bookmarks of bones, their original material (connective tissue, cartilage) is preserved between them. With the help of this material, bones are fused, i.e. a continuous connection is formed. Discontinuous connections develop at later stages of ontogenesis in terrestrial vertebrates and are more advanced, since they provide more differentiated mobility of parts of the skeleton. They develop due to the appearance of a gap in the original material preserved between the bones. In the latter case, the remnants of cartilage cover the articulating surfaces of the bones. There is also a third, intermediate type of connections - half-joint.
Continuous connections. Continuous connection - synarthrosis,or fusion,occurs when the bones are connected to each other by connecting tissue. At the same time, movements are extremely limited or completely absent. By the nature of the connecting tissue, connective tissue adhesions are distinguished, or syndesmosis(fig. 1.5, A), cartilaginous adhesions, or synchondrosis, and fusion with bone tissue - synostosis.
Syndesmosesthere are three kinds: 1) interosseous membranes,for example between the bones of the forearm or
shins; 2) ligaments,connecting bones (but not connected to joints), such as ligaments between the processes of the vertebrae or their arches; 3) seamsbetween the bones of the skull.
The interosseous membranes and ligaments allow some displacement of the bones. In the seams, the layer of connective tissue between the bones is very insignificant and movement is impossible.
Synchondrosisis, for example, the connection of the I rib with the sternum by means of costal cartilage, the elasticity of which allows some mobility of these bones.
Synostosisdevelop from syndesmosis and synchondrosis with age, when connective tissue or cartilage between the ends of some bones is replaced bone tissue... An example is the fusion of the sacral vertebrae and overgrown sutures of the skull. Naturally, there is no movement here.
3. Discontinuous (synovial) bone connections. Joint structure. Classification of joints by the shape of the articular surfaces, the number of axes and by function.
Discontinuous connections. Interrupted connection - diarthrosis,articulation, or joint,characterized by an insignificant space (gap) between the ends of the connecting bones. Distinguish between joints simple,formed by only two bones (for example, the shoulder joint), complex - when more bones are included in the joint (for example, the elbow joint), and combined,allowing movement only simultaneous with movement in other anatomically separate joints (for example, the proximal and distal radioulnar joints). The composition of the joint includes: articular surfaces, an articular bag, or capsule, and an articular cavity.
Articular surfacesconnecting bones more or less correspond to each other (congruent). On one bone that forms a joint, the articular surface is usually convex and is called heads.The concavity corresponding to the head develops on the other bone - depression,or fossa.Both the head and the fossa can be formed by two or more bones. The articular surfaces are covered with hyaline cartilage, which reduces friction and facilitates movement in the joint.
Joint baggrows to the edges of the articular surfaces of the bones and forms a sealed articular cavity. The bursa consists of two layers. The superficial, fibrous layer, formed by fibrous connective tissue, merges with the periosteum of the articulating bones and has a protective function. The inner, or synovial, layer is rich in blood vessels. It forms outgrowths (villi) that secrete a viscous liquid - synovia,which lubricates the mating surfaces and makes them easier to slide. There is very little synovium in normally functioning joints, for example, in the largest of them - the knee - no more than 3.5 cm 3. In some joints (knee), the synovium forms folds in which fat is deposited, which has a protective function here. In other joints, for example, in the shoulder, the synovium forms external protrusions, above which there is almost no fibrous layer. These protrusions in the form synovial bagsare located in the area of \u200b\u200btendon attachment and reduce friction during movement.
Articular cavityis called a hermetically closed slit space, limited by the articulating surfaces of the bones and the articular bag. It is filled with synovium. There is negative pressure (below atmospheric) in the articular cavity between the articular surfaces. The atmospheric pressure experienced by the capsule helps to strengthen the joint. Therefore, in some diseases, the sensitivity of the joints to fluctuations in atmospheric pressure increases, and such patients can "predict" changes in the weather. The tight pressing of the articular surfaces to each other in a number of joints is due to the tone, or active tension of the muscles.
In addition to the obligatory ones, auxiliary formations can be found in the joint. These include articular ligaments and lips, intra-articular discs, menisci, and sesamoid (from Arab, sesamo- grain) bones.
Articular ligamentsare bundles of dense fibrous tissue. They are located in the thickness or over the joint capsule. These are local thickenings of its fibrous layer. Throwing over the joint and attaching to the bones, the ligaments strengthen the joint. However, their main role is to limit the range of motion: they do not allow it to go beyond certain limits. Most ligaments are not elastic, but very strong. Some joints, such as the knee, have intra-articular ligaments.
Joint lipsconsist of fibrous cartilage, annularly enclosing the edges of the articular cavities, the area of \u200b\u200bwhich they supplement and increase. The joint lips give the joint more strength, but reduce the range of motion (for example, the shoulder joint).
Discsand menisciare cartilage pads - solid and with a hole. They are located inside the joint between the articular surfaces, and along the edges they grow together with the articular bag. The surfaces of the discs and menisci follow the shape of the articular surfaces of the bones adjacent to them on both sides. The discs and menisci promote a variety of motion in the joint. They are found in the knee and mandibular joints.
Sesamoid bonessmall and located near some joints. Some of these bones lie in the thickness of the articular capsule and, increasing the area of \u200b\u200bthe glenoid fossa, articulate with the articular head (for example, in the joint of the big toe); others are included in the tendons of muscles that extend over the joint (for example, the patella, which is enclosed in the tendon of the quadriceps femoris muscle). Sesamoid bones also belong to auxiliary muscle formations.
Joint classification is based on a comparison of the shape of articulated surfaces with segments of various geometric shapes of rotation, resulting from the movement of a straight or curved line (the so-called generatrix) around a fixed conventional axis. Different forms of motion of the generating line give different bodies of revolution. For example, a straight generatrix, rotating parallel to the axis, will describe a cylindrical figure, and a semicircle generatrix gives a ball. The articular surface of a certain geometric shape allows movements only along the axes inherent in this shape. As a consequence, joints are classified into uniaxial, biaxial, and triaxial (or nearly multi-axial).
Uniaxial jointscan be cylindrical or block-shaped.
Cylindrical jointhas articular surfaces in the form of cylinders, and the convex surface is covered by a concave cavity. The axis of rotation is vertical, parallel to the long axis of the articulating bones. It provides movement along one vertical axis. In a cylindrical joint, axial rotation in and out is possible. Examples are the joints between the radius and ulna and the joint between the epistropheus tooth and the atlas.
Block jointis a kind of cylindrical, differs from it in that the axis of rotation runs perpendicular to the axis of the rotating bone and is called transverse or frontal. Flexion and extension are possible in the joint. An example is the interflange joints.
Biaxial jointscan be saddle(in one direction, the articular surface is concave, and in the other, perpendicular to it, convex) and ellipsoidal(articular surfaces are ellipsoidal). An ellipse as a body of revolution has only one axis. The possibility of movement in the ellipsoid joint around the second axis is due to incomplete coincidence of the articular surfaces. Biaxial joints allow movement around two, located in the same plane, but mutually perpendicular axes: flexion and extension around the frontal axis, adduction (to the midplane) and abduction around the sagittal axis. An example of an ellipsoid joint is the wrist joint, and the saddle joint is the carpometacarpal joint of 1 finger.
Triaxial jointsare spherical and flat.
Ball joints -the most mobile joints. Movements in them occur around three main mutually perpendicular and intersecting in the center of the head axes: frontal (flexion and extension), vertical (inward and outward rotation) and sagittal (adduction and abduction). But an infinite number of axes can be drawn through the center of the articular head, therefore the joint turns out to be practically multiaxial. This is, for example, the shoulder joint.
One of the varieties of the spherical joint is the nut joint, in which a significant part of the articular spherical head is covered by the spherical articular cavity and, as a result, the range of motion is limited. An example is the hip joint. Movements in it can occur in any planes, but the range of movements is limited.
Flat joint -it is a segment of a ball with a very large radius, due to which the curvature of the articulating surfaces is very insignificant: the head and the fossa cannot be distinguished. The joint is inactive and allows only slight sliding of the articulating surfaces in different directions. An example is the joint between the articular processes of the thoracic vertebrae.
In addition to the described movements, in biaxial and triaxial joints, a movement called circular is also possible. With this movement, the end of the bone, opposite to that fixed in the joint, describes a circle, and the bone as a whole describes the surface of the cone.
Half-jointcharacterized by the fact that the bones in it are connected by a cartilaginous lining, which has a slit-like cavity inside. The articular capsule is missing. Thus, this type of connection is a transitional form between synchondrosis and diarthrosis (between the pubic bones of the pelvis).
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(GENERAL SYNDESMOLOGY)
The science of connecting bones is called syndesmology.
The skeleton, together with the muscles, performs the functions of support and movement due to the fact that all bones are connected to each other and form movable bone levers. The nature of the connections depends on the function of a particular bone link.
All bone connections in the dog's body are divided into 2 types: continuous and discontinuous, or synovial (joints). The semi-joints (symphysis) are of the transitional type.
Continuous connections - synarthrosis - the connection of bones using various types of connective tissue. This is the most ancient type of connection in phylogeny, inactive or functionally immobile, which is explained by the absence of an articular space between the connecting bones, occurs mainly between the bones of the axial skeleton.
Depending on the nature of the tissue, the following types of continuous connections are distinguished: fibrous, cartilaginous and bone.
Fibrous joints (syndesmosis)carried out with the help of dense fibrous connective tissue. Syndesmosis is the connection of bones with the help of ligaments, interosseous membranes (membranes), sutures, hammering. Ligaments are thick bundles of dense connective tissue, or plates, that spread from one bone to another, strengthening joints or limiting their movement. In those places where the bone elements diverge strongly during movement, the ligaments have a large number of elastic fibers - sinelastoses (yellow ligaments, ligamentum nuchal).
Interosseous membranes are extensive connective tissue plates stretched between bones (membranes of the forearm, lower leg, atlantooccipital joint, obturator membranes of the pelvic bones).
Seams are the connection of the edges of the roof bones and the facial part of the skull with each other using thin layers of fibrous connective tissue. The configuration of the bone sutures is different. So, between the bones roofthere are jagged sutures, the cerebral section is connected to the facial one with the help of a scaly suture, and the bones of the face are interconnected by a smooth suture. The strength of the seams increases in the following sequence: smooth (harmonious) - serrated - scaly. The periosteum, without interruption, covers the suture line. With age, collagen fibers of the connective tissue calcify and turn into coarse fibrous tissue (suture closure).
Hammering (homphosis) is the connection of the tooth with the bone tissue of the dental alveoli, where there is a fibrous connective tissue between the root of the tooth and the wall of the alveoli - the alveolar periosteum. Its fibers grow on the one side into the wall of the hole, and on the other - into the cement covering the tooth root.
Cartilage joints (synchondrosis)are carried out using fibrous cartilage tissue. Synchondrosis is distinguished by its strength, which depends on the thickness of the cartilage layer between the bones and its structure. Synchondrosis are permanent (between the ribs and costal cartilages of the vertebrae, segments of the sternum) and temporary, remaining only up to a certain age, after which the cartilage is replaced by bone tissue (joints of the diaphysis and epiphysis of the tubular bone, synchondrosis of the skull, pelvic bones in young dogs).
A variety of synchondrosis are symphysis (from the Greek. Symphysis - accretion). They are cartilage joints devoid of an articular capsule. In the thickness of the cartilage there is a small slit-like cavity filled with fluid, the synovium is absent (pelvic suture, joints between the ribs and costal cartilage).
Bone joints (synostosis)appear as synchondrosis ossifies. In this case, crystals of hydroxyapatite and amorphous tricalcium phosphate are deposited in the intercellular substance of the fibrous cartilage.
Discontinuous synovial joints, or joints, are movable joints of bones, in which there is always a "discontinuity" between them - the joint space. Each joint has articular surfaces covered with articular cartilage, an articular capsule, an articular cavity filled with synovial fluid (Fig. 9).
The articular surfaces are covered with hyaline cartilage (at the temporomandibular joint, fibrous cartilage). Cartilage thickness is in direct proportion to the functional load experienced.
Figure: 9. Diagram of the structure of the synovial connection (joint) (according to Pavlova V.P., 1980)
The articular cartilage is devoid of blood vessels and perichondrium. It consists of 75-80% water and 20-25% dry matter, about half of which is collagen and proteoglycans. The first gives the cartilage strength, the second - elasticity.
The cartilage is separated from the underlying bone by a sinusoidal line that forms many protrusions directed towards the cartilage, into which the sinusoidal blood capillaries... In this case, normally between the cartilage and the bone capillaries there are always plates of osteoid tissue (subchondral bone) (Fig. 10). There are two known ways of feeding the cartilage: the first is due to the synovial environment of the joint (diffusion-compression); the second is due to the glomerular vascular terminals of the subchondral bone. In the articular cartilage, three zones are distinguished: superficial, intermediate (uncalcified) and deep (calcified), which is saturated with calcium salts and directly adjoins the bone. The articular cartilage protects the articular ends from mechanical stress, and the cartilage deformations arising from movement are reversible.
Figure: 10. The structure of the articular cartilage and subchondral bone. SEM image. X300 (original from N. A. Slesarenko's preparation)
The articular capsule firmly grows together with the periosteum, forming a closed composite cavity. The capsule consists of two layers. The outer one is represented by a fibrous membrane, consisting of fibrous connective tissue. In places, the fibrous membrane forms thickenings - ligaments that strengthen the joint capsule. Ligaments can be located in the thickness of the capsule (capsular ligaments), outside it (extracapsular ligaments) or inside the joint (intracapsular ligaments), the latter are covered with a synovial membrane and are especially numerous in the knee joint.
Like the periosteum, the joint capsule is rich in blood vessels and nerves. Nerve endings penetrate into its synovial layer.
Figure: 11. The surface of the synovial villi (picture from a scanned electronogram)
(original)
The inner layer of the capsule is formed by a thin, smooth, shiny synovial membrane that lines the fibrous membrane from the inside and continues on the surface of the bone not covered with articular cartilage. The synovial membrane consists of flat and villous parts. The latter has many small outgrowths - synovial villi, rich in blood vessels (Fig. 11) and producing synovia by ultrafiltration from the blood. The number of villi is directly proportional to the degree of joint mobility. If the articulating surfaces do not correspond to each other (discongruent), the synovial membrane forms synovial folds. The largest folds (knee joint) contain accumulations of adipose tissue.
The synovial membrane consists of a plate formed by reticular and collagen fibrils, on which a layer of synovial cells - synoviocytes - is located. There are two types of synoviocytes: secretory and phagocytic. The former produce synovial fluid (contains 95% water, the rest is proteins, salts, polysaccharides; the main component is hyaluronic acid); the latter perform a protective function. The synovial fluid provides trophism of the surface layers of the articular cartilage and serves as a universal joint lubricant.
The articular cavity is a narrow gap located between the articular surfaces covered with cartilage and hermetically sealed by the synovial membrane. Normally, even in large joints, such as the knee, the articular cavity can only hold 2-2.5 cm 3 of synovial fluid. The shape of the articular cavity depends on the shape of the articulating surfaces, the presence of auxiliary formations or intracaisular ligaments.
Auxiliary joint formations are designed to eliminate the inconsistency (discongruence) of the articular surfaces in shape, and are presented in the form of synovial folds, articular discs, menisci, articular lips and synovial bursae.
Joints are widely represented in the dog's body and differ in a variety of shapes and structures, which, however, are closely related to the function they perform and are determined by the functional characteristics of the area of \u200b\u200bthe body in which they are located.
Figure: 12. Location of bone elements in a normal hip joint (original drawing from the preparation)
Figure: 13, andand b.Location and shape of bone elements in the hip joint affected by dysplasia (original drawing from the preparation)
Depending on the number and structural features of the articular surfaces involved in the formation of the joint, and their relationship, the joints are divided into simple (two articular surfaces - shoulder, hip), complex (more than two articular surfaces - carpal, tarsal), combined (one articular surface combines movements in different directions - the elbow joint) and complex (there is a disc or meniscus between the articular surfaces, dividing the joint cavity into two sections - the temporomandibular and knee joints). Figure: 14. Structure normal femur dogs (original drawing from the preparation)
According to the shape of the articular surfaces, which determine the number of axes of rotation, the joints are divided into one-, two- and multiaxial.
In shape, uniaxial joints are cylindrical (atlanto-axial joint), block (interphalangeal joints) and helical. The latter differ from block-like ones in that the ridge separating the block is placed not perpendicular to the axis of rotation, but in a spiral (tibia-talus joint).
Biaxial joints are classified into ellipsoidal (wrist, metacarpophalangeal, metatarsophalangeal) and condylar (knee and atlanto-occipital).
Polyaxial joints are classified as spherical and flat. The first type includes the shoulder and hip joints (the latter is considered to be cup-shaped due to the considerable depth of the glenoid fossa, enlarged articular lip). Flat joints, although they can make movements around three axes, are characterized by a small amount of movement (facet joints, sacroiliac, intercarpal, carpometacarpal, tarsometatarsal).
Joint mobility depends on the age and sex of the animals. It is greatest in young females. With age, the mobility of the joints decreases, which is associated with sclerotization of the fibrous membrane and ligaments, as well as age-related destructive changes in the tissues of the joint (arthrosis, ankylosis).
Of greatest interest is the study of such pathology as joint dysplasia. At present, dysplasia is considered as a polygenic inherited disease, the structural manifestation of which is the discrepancy between the size and shape of the articular surfaces (Fig. 12-15) (Samoshkin IB, 1995-1998).
Figure: 15. The structure of the femur of a dog with dysplasia: change in the shape of the head and neck of the bone (original drawing from the preparation)
The disease can affect all joints of the body, but it is most clearly manifested in the example of the hip joints. A characteristic feature of this pathology is the staging of the process, which, as a rule, coincides with the stages of hereditary osteochondropathy (although it does not always repeat them exactly). The immediate cause of this pathology is, apparently, a violation of the embryonic development of synovial joints, which is genetically determined.
In this regard, animals susceptible to this pathology are not allowed to genetic work.
Having considered the general issues of the structure of the osteoarticular system, let us dwell in more detail on the structure of the dog's skeleton, which, like in other animals, is subdivided into axial (vertebral column, chest, skull) and limb skeleton (peripheral skeleton) (Fig. 16).
All joints of bones are subdivided into continuous, discontinuous and semi-joints (symphysis), (Fig. 105).
Continuous joints of bones, formed with the participation of connective tissue are fibrous, cartilaginous and bone connections.
TO fibrous joints (junctura fibrosa),or syndesmoses (syndesmoses), include ligaments, membranes, sutures, fontanelles and "hammering". Ligaments(ligamenta) in the form of bundles of dense fibrous connective tissue connect adjacent bones. Interosseous membranes(membranae interossei) are stretched, as a rule, between the diaphysis of tubular bones. Sutures (suturae)- these are joints in the form of a thin connective tissue layer between the bones. Distinguish flat seams(sutura plana), which are located between the bones of the facial part of the skull, where
Figure: 105.Types of bone joints (diagram).
A - joint, B - syndesmosis, C - synchondrosis, D - symphysis.
1 - periosteum, 2 - bone, 3 - fibrous connective tissue, 4 - cartilage, 5 - synovial membrane, 6 - fibrous membrane, 7 - articular cartilage, 8 - articular cavity, 9 - gap in the interpubic disc, 10 - interpubic disc.
the smooth edges of the bones are connected. Serrated seams(suturae serratae) are characterized by irregularity of the connecting bone edges (between the bones of the medullary skull). An example scaly sutures (suturae squamose) is the junction of the temporal bone scales with the parietal bone. By hammering (gomphosis),or tooth-alveolar connection (articulatio dentoalveolaris)is called the connection of the root of the tooth with the walls of the dental alveoli, between which there are connective tissue fibers.
Connections of bones using cartilage are called tight connections, or synchondrosis (juncturae cartilagineae, s. synchondrose).Distinguish between permanent synchondrosis, existing throughout life, for example, intervertebral discs, and temporary. Temporary synchondrosis, which at a certain age are replaced by bone tissue, for example, epiphyseal cartilage of tubular bones. Symphysis (semi-joints) (symphyses),in which there is a narrow slit cavity in the cartilaginous layer between the bones, they occupy an intermediate position between continuous and discontinuous joints (joints). An example of a semi-joint is the pubic symphysis.
Bone adhesions (synostosis, synostoses) are formed as a result of the replacement of synchondrosis with bone tissue.
Discontinuous bone connections are joints,or synovial connections(articulatio, s. articulatioms synoviales).The joints are characterized by the presence of articular surfaces covered with cartilage, an articular cavity with synovial fluid and an articular capsule. Some joints have additional formations in the form of articular discs, menisci or articular lip. Articular surfaces (facies articulares) can correspond to each other in configuration (be congruent) or differ in shape and size (be incongruent). Articular cartilage(cartilago articularis) (0.2 to 6 mm thick) has surface, intermediate and deep zones.
Articular capsule (capsula articularis) is attached to the edges of the articular cartilage or at some distance from it. A fibrous membrane from the outside and a synovial membrane from the inside are isolated from the capsule. Fibrous membrane(membrana fibrosa) strong and thick, formed by fibrous connective tissue. In some places, the fibrous membrane thickens, forming ligaments that strengthen the capsule. Some joints in the articular cavity have intra-articular ligaments covered with a synovial membrane. Synovial membrane(membrana synovialis) thin, it lines the fibrous membrane from the inside, forms micro outgrowths - synovial villi. Articular cavity(cavum articulare) is a closed slit space bounded by the articular surfaces of the bones and the articular capsule. In the articular cavity there is a mucus-like synovial fluid that wets the articular surfaces. Joint discsand menisci(disci et menisci articulares) are intra-articular cartilaginous plates of various shapes that eliminate or reduce incongruity (incongruence) of the articular surfaces. (For example, at the knee joint). Articular lip(labrum articulare) is present in some joints (shoulder and hip). It is attached along the edge of the articular surface, increasing the depth of the glenoid fossa.
Joint classification. Anatomical and biomechanical classification of joints is distinguished. According to the anatomical classification, joints are divided into simple, complex, complex and combined joints. Simple joint(artimlatio simplex) is formed by two articulating surfaces. Complex joint(artimlatio composita) is formed by three or more articular surfaces of bones. A complex joint has an intra-articular disc or meniscus. The combined joints are anatomically isolated, however, they function together (for example, the temporomandibular joints) (Fig. 106).
Joints are classified according to the number of axes of rotation. Uniaxial, biaxial, and multiaxial joints are distinguished. Uniaxial joints have one axis around which flexion occurs
Figure: 106.Types of joints (diagram). A - block-shaped, B - ellipsoid, C - saddle-shaped, D - spherical.
bathing-extension or abduction-adduction, or turning outwards (supination) and inwards (pronation). Uniaxial joints in the form of articular surfaces include block and cylindrical joints. Biaxial joints have two axes of rotation. For example, flexion and extension, abduction and adduction. These joints include elliptical, saddle joints. Examples of polyaxial joints are ball-shaped, flat joints in which various types of movement are possible.
Skull joints
The bones of the skull are connected to each other mainly by means of continuous joints - sutures. The exception is the temporomandibular joint.
The adjacent bones of the skull are connected with sutures. The medial edges of the two parietal bones are connected by the dentate sagittal suture (sutura sagittalis),frontal and parietal bones - dentate coronal suture (sutura coronalis),parietal and occipital bones - with the dentate lambdoid suture (sutura lambdoidea).The scales of the temporal bone with the large wing of the sphenoid bone and the parietal bone are connected scaly seam (sutura squamosa).The bones of the facial part of the skull are connected flat (harmonious) seams (sutura plana).Flat sutures include internasal, lacrimal-conchial, intermaxillary, palatine-ethmoid and other sutures. Sutures are usually named after the two connecting bones.
There are cartilaginous joints in the region of the base of the skull - synchondrosis.Between the body of the sphenoid bone and the basilar part of the occipital bone there is sphenoid-occipital synchondrosis (synchondrosis sphenopetrosa),which is replaced by bone tissue with age.
Temporomandibular joint (art. temporomandibularis), paired, complex (has an articular disc), ellipsoidal, formed by the articular head of the lower jaw, the mandibular fossa and the articular tubercle of the temporal bone, covered with fibrous cartilage (Fig. 107). The head of the lower jaw(caput mandibulae) has the shape of a roller. Mandibular fossa(fossa mandibularis) of the temporal bone does not completely enter the cavity of the temporomandibular joint, therefore, its extracapsular and intracapsular parts are distinguished. The extracapsular part of the mandibular fossa is located behind the stony-scaly fissure, the intracapsular part is anterior to this fissure. This part of the fossa is enclosed in an articular capsule, which extends to the articular tubercle (tuberculum articulae) of the temporal bone. Articular capsule
Figure: 107.Temporomandibular joint, right. Outside view. The joint was opened with a sagittal cut. The zygomatic arch is removed.
1 - mandibular fossa, 2 - upper floor of the articular cavity, 3 - articular tubercle, 4 - upper head of the lateral pterygoid muscle, 5 - lower head of the lateral pterygoid muscle, 6 - tubercle of the maxillary bone, 7 - medial pterygoid muscle, 8 - pterygo-mandibular suture, 9 - the angle of the lower jaw, 10 - the stylo-mandibular ligament, 11 - the branch of the lower jaw, 12 - the head of the lower jaw, 13 - the lower floor of the articular cavity of the temporomandibular joint, 14 - the articular capsule, 15 - the articular disc.
wide, free, on the lower jaw it covers her neck. The articular surfaces are covered with fibrous cartilage. Inside the joint there is articular disc(discus articularis), biconcave, which divides the articular cavity into two sections (floors), upper and lower. The edges of this disc are fused with the joint capsule. The upper floor cavity is lined with upper synovial membrane(membrana synovialis superior), the lower floor of the temporomandibular joint - lower synovial membrane(membrana synovialis inferior). Part of the tendon bundles of the lateral pterygoid muscle is attached to the medial edge of the articular disc.
The temporomandibular joint is strengthened with intracapsular (intraarticular) and capsular ligaments, as well as extracapsular ligaments. In the cavity of the temporomandibular joint, the anterior and posterior disco-temporal ligaments are located, extending from the upper edge of the disc upward, anteriorly and posteriorly, and to the zygomatic arch. Intra-articular (intracapsular) lateral and medial disco-mandibular ligaments run from the lower edge of the disc down to the neck of the lower jaw. Lateral ligament(lig. laterale) is a lateral thickening of the capsule, it has the shape of a triangle, the base facing the zygomatic arch (Fig. 108). This ligament begins at the base of the zygomatic process of the temporal bone and on the zygomatic arch, goes down to the neck of the lower jaw.
Figure: 108.Lateral ligament of the temporomandibular joint, right. Outside view. 1 - zygomatic arch, 2 - zygomatic bone, 3 - coronoid process of the lower jaw, 4 - maxillary bone, 5 - second molar, 6 - lower jaw, 7 - third molar, 8 - chewing tuberosity, 9 - branch of the lower jaw, 10 - awl-mandibular ligament, 11 - the condylar process of the lower jaw, 12 - the anterior (external) part of the lateral ligament of the temporomandibular joint, 13 - the posterior (internal) part of the lateral ligament of the temporomandibular joint, 14 - the mastoid process of the temporal bone, 15 - external ear canal.
Medial ligament (lig. Mediale) runs along the ventral side of the capsule of the temporomandibular joint. This ligament begins at the inner edge of the articular surface of the mandibular fossa and the base of the spine of the sphenoid bone and attaches to the neck of the mandible.
Outside the joint capsule of the joint, there are two ligaments (Fig. 109). Wedge-mandibular ligament(lig. sphenomandibulare) begins on the spine of the sphenoid bone and attaches to the tongue of the lower jaw. Awl-mandibular ligament(lig. stylomandibulare) goes from the styloid process of the temporal bone to the inner surface of the lower jaw, near its angle.
The following movements are performed in the right and left temporomandibular joints: lowering and raising the lower jaw, corresponding to the opening and closing of the mouth, advancing the lower jaw forward and returning to its original position; movement of the lower jaw to the right and left (lateral movements). Lowering of the lower jaw occurs when the heads of the lower jaw rotate around the horizontal axis in the lower floor of the joint. The movement of the lower jaw to the sides is performed with the participation of the articular disc. In the right temporomandibular joint, when moving to the right (and in the left joint when moving to the left), the head of the lower jaw rotates under the articular disc (around the vertical axis), and in the opposite joint, the head with the disc moves forward (sliding) onto the articular tubercle.
Figure: 109.Extra-articular ligaments of the temporomandibular joint. Inside view. Sagittal cut. 1 - sphenoid sinus, 2 - lateral plate of the pterygoid process of the sphenoid bone, 3 - pterygoid-spinous ligament, 4 - spine of the sphenoid bone, 5 - neck of the lower jaw, 6 - sphenoid-mandibular ligament, 7 - styloid process of the temporal bone, 8 - condylar process of the lower jaw, 9 - awl-mandibular ligament, 10 - opening of the lower jaw, 11 - pterygoid hook, 12 - pterygoid tuberosity, 13 - angle of the lower jaw, 14 - maxillary-hyoid line, 15 - molars, 16 - premolars, 17 - canines, 18 - hard palate, 19 - medial pterygoid plate, 20 - inferior turbinate, 21 - wedge-palatine opening, 22 - middle turbinate, 23 - superior turbinate, 24 - frontal sinus.
Connections of the bones of the trunk
Vertebral connections
There are various types of connections between the vertebrae. The bodies of neighboring vertebrae are connected using intervertebral discs(disci intervertebrales), processes - using joints and ligaments, and arcs - using ligaments. The intervertebral disc has a central part
Figure: 110.Intervertebral disc and facet joints. View from above.
1 - lower articular process, 2 - articular capsule, 3 - articular cavity, 4 - upper articular process, 5 - costal process of the lumbar vertebra, 6 - annulus fibrosus, 7 - nucleus pulposus, 8 - anterior longitudinal ligament, 9 - posterior longitudinal ligament, 10 - lower vertebral notch, 11 - yellow ligament, 12 - spinous process, 13 - supraspinous ligament.
takes gelatinous nucleus(nucleus pulposus), and the peripheral part - fibrous ring(annulus fibrosus), (fig. 110). The gelatinous nucleus is elastic; when the spine is tilted, it shifts towards extension. The annulus fibrosus is built from fibrous cartilage. There is no intervertebral disc between the atlas and the axial vertebra.
The connections of the vertebral bodies are reinforced by the anterior and posterior longitudinal ligaments (Fig. 111). Anterior longitudinal ligament(lig. longitudinale anterius) goes along the front surface of the vertebral bodies and intervertebral discs. Posterior longitudinal ligament(lig. longitudinale posterius) goes inside the spinal canal along the back surface of the vertebral bodies from the axial vertebra to the level of the first coccygeal vertebra.
Between the arches of adjacent vertebrae yellow ligaments(ligg.flava), formed by elastic connective tissue.
The articular processes of adjacent vertebrae form facet,or intervertebral joints(art. zygapophysiales, s. intervertebrales). The articular cavity is located according to the position and direction of the articular surfaces. In the cervical region, the articular cavity is oriented almost in the horizontal plane, in the thoracic region - in the frontal plane and in the lumbar region - in the sagittal plane.
The spinous processes of the vertebrae are interconnected with the help of interspinous and supraspinous ligaments. Interspinous ligaments(ligg. interspinalia) are located between adjacent spinous processes. Supraspinous ligament(lig. supraspinale) is attached to the tops of the spinous processes of all vertebrae. In the cervical spine, this ligament is called nuchal ligament(lig. nuchae). Between the transverse processes are located transverse ligaments(ligg. intertransversaria).
Lumbosacral junction, or lumbosacralthe joint (articulatio lumbosacralis), located between the V-th lumbar vertebra and the base of the sacrum, is strengthened by the ilio-lumbar ligament. This ligament goes from the posterior-superior edge of the ilium to the transverse processes of the IV and V lumbar vertebrae.
Sacrococcygeal joint (art. sacrococcygea) represents the connection of the apex of the sacrum with the 1st coccygeal vertebra. The junction of the sacrum with the coccyx is strengthened by the paired lateral sacrococcygeal ligament, which runs from the lateral sacral ridge to the transverse process of the 1st coccygeal vertebra. The sacral and coccygeal horns are interconnected by connective tissue (syndemosis).
Figure: 111.Connections of the cervical vertebrae and the occipital bone. Medial view. The vertebral column and occipital bone are sawn in the median sagittal plane.
1 - the basilar part of the occipital bone, 2 - the tooth of the axial vertebra, 3 - the upper longitudinal bundle of the cruciate ligament of the atlas, 4 - the integumentary membrane, 5 - the posterior longitudinal ligament, 6 - the posterior atlanto-occipital membrane, 7 - the transverse ligament of the atlas, 8 - the lower longitudinal bundle of the cruciate ligament of atlas, 9 - yellow ligaments, 10 - interspinous ligament, 11 - intervertebral foramen, 12 - anterior longitudinal ligament, 13 - articular cavity of the median atlanto-axial joint, 14 - anterior arch of the atlas, 15 - apex ligament, 16 - anterior atlanto-occipital membrane, 17 - anterior atlanto-occipital ligament.
Figure: 112.Atlanto-occipital and atlanto-axial joints. Back view. The posterior occipital bone and the posterior arch of the atlas were removed. 1 - clivus, 2 - ligament of the apex of the tooth, 3 - pterygoid ligament, 4 - lateral part of the occipital bone, 5 - tooth of the axial vertebra, 6 - transverse foramen atlas, 7 - atlas, 8 - axial vertebra, 9 - lateral atlanto-axial joint , 10 - atlanto-occipital joint, 11 - the canal of the hyoid nerve, 12 - the anterior edge of the foramen magnum.
Connections of the spine to the skull
Between the occipital bone of the skull and the first cervical vertebrae there is atlantooccipital joint(art. atlanto-occipitalis), combined (paired), condylar (ellipsoid or condylar). This joint is formed by two condyles of the occipital bone, connected to the corresponding superior glenoid fossa of the atlas (Fig. 112). The articular capsule is attached along the edge of the articular cartilage. This joint is strengthened by two atlanto-occipital membranes. Anterior atlanto-occipital membrane(membrana atlanto-occipitalis anterior) stretched between the anterior edge of the occipital foramen of the occipital bone and the anterior arch of the atlas. Posterior atlantooccipital membrane(membrana atlantooccipitalis posterior) thinner and wider, located between the posterior semicircle of the occipital foramen and the upper edge of the posterior arch of the atlas. The lateral sections of the posterior atlantooccipital membrane are called lateral atlanto-occipital ligaments(lig. atlantooccipitale laterale).
At the right and left atlanto-occipital joints around the frontal axis, the head is tilted forward and backward (nodding movements), around the sagittal axis - abduction (head tilt to the side) and adduction (reverse movement of the head to the middle.
Between the atlas and the axial vertebrae, there is an unpaired median atlanto-axial joint and a paired lateral atlanto-axial joint.
Mid-atlanto-axial joint (art. atlantoaxialis mediana)formed by the anterior and posterior articular surfaces of the axial vertebra tooth. The tooth in front is connected to the fossa of the tooth located on the back side of the anterior arch of the atlas (Fig. 113). Behind the tooth articulates with transverse ligament of atlas(lig. transversum atlantis), stretched between the inner surfaces of the lateral masses of the atlant. The anterior and posterior articulations of the tooth have separate articular cavities and articular capsules, but are considered as a single median atlanto-axial joint, in which head rotations about the vertical axis are possible: outward rotation of the head - supination, and inward rotation of the head - pronation.
Lateral atlanto-axial joint (art.atlantoaxialis lateralis), paired (combined with the median atlanto-axial joint), formed by the glenoid fossa on the lateral mass of the atlas and the superior articular surface on the body of the axial vertebra. The right and left atlanto-axial joints have separate joint capsules. The joints are flat in shape. In these joints, sliding occurs in the horizontal plane during rotation in the median atlanto-axial joint.
Figure: 113.Connection of the atlas with the tooth of the axial vertebra. View from above. Horizontal cut at the level of the axial vertebra tooth. 1 - tooth of the axial vertebra, 2 - articular cavity of the median atlanto-axial joint, 3 - transverse ligament of the atlas, 4 - posterior longitudinal ligament, 5 - integumentary membrane, 6 - transverse foramen of the axial vertebra, 7 - lateral mass of the atlas, 8 - anterior arch of the atlas.
The median and lateral atlanto-axial joints are reinforced with several ligaments. Apex ligament(lig. apicis dentis), unpaired, stretched between the middle of the posterior edge of the anterior circumference of the foramen magnum and the apex of the tooth of the axial vertebra. Pterygoid ligaments(ligg.alaria), paired. Each ligament begins on the lateral surface of the tooth, runs obliquely upward and laterally, and attaches to the inner side of the occipital condyle.
Behind the ligament of the apex of the tooth and pterygoid ligaments is cruciate ligament of atlas(lig. cruciforme atlantis). It is formed by the transverse ligament of the atlas and longitudinal beams(fasciculi longitudinales) fibrous tissue extending up and down from the transverse ligament of the atlas. The upper bundle ends on the anterior semicircle of the occipital foramen, the lower one - on the posterior surface of the axial vertebral body. Behind, from the side of the spinal canal, the atlanto-axial joints and their ligaments are covered with a wide and strong connective tissue membrane(membrana tectoria). The lining membrane is considered part of the posterior longitudinal ligament of the spinal column. Above, the integumentary membrane ends on the inner surface of the anterior edge of the foramen magnum.
Spinal column (columna vertebralis)it is formed by vertebrae connected by intervertebral discs (symphysis), joints, ligaments and membranes. The spine forms curves in the sagittal and frontal planes (kyphosis and lordosis), it has great mobility. The following types of spinal column movements are possible: flexion and extension, abduction and adduction (lateral bending), twisting (rotation) and circular motion.
Connections of the ribs with the spine and with the sternum.
The ribs are connected to the vertebrae using costal-vertebral joints(artt. costovertebrales), which include the joints of the rib head and costal-transverse joints (Fig. 114).
Rib head joint (art. capitis costae) is formed by the articular surfaces of the upper and lower costal fossae (half-pit) of two adjacent thoracic vertebrae and the rib head. From the ridge of the rib head to intervertebral disc in the joint cavity there is an intra-articular ligament of the rib head, which is absent at the 1st rib, as well as at the 11th and 12th ribs. Outside, the capsule of the rib head is reinforced with a radiant ligament of the rib head (lig. Capitis costae radiatum), which begins on the front side of the rib head and attaches to the bodies of adjacent vertebrae and to the intervertebral disc (Fig. 115).
Costal-transverse joint (art. costotransversaria) is formed by the tubercle of the rib and the costal fossa of the transverse process. This joint is absent in the 11th and 12th ribs. Strengthens the capsule costal ligament(lig. costotransversarium), which connects the neck of the underlying rib with the bases of the spinous and transverse processes of the overlying vertebra. Lumbar
Figure: 114.Ligaments and joints that connect the ribs to the vertebra. View from above. Horizontal cut through the costal-vertebral joints.
1 - articular cavity of the facet joint, 2 - transverse process, 3 - lateral costal ligament, 4 - rib tubercle, 5 - costal-transverse ligament, 6 - rib neck, 7 - rib head, 8 - radial ligament of the rib head, 9 - body vertebra, 10 - articular cavity of the rib head joint, 11 - articular cavity of the costal-transverse joint, 12 - upper articular process of the VIII thoracic vertebra, 13 - lower articular process of the VII thoracic vertebra.
costal ligament(lig. lumbocostale) stretched between the costal processes of the th lumbar vertebrae and the lower edge of the 12th rib.
In the combined costal-transverse joint and the joint of the head of the rib, rotational movements are carried out around the neck of the rib, while the front ends of the ribs connected to the sternum are raised and lowered.
Connections of the ribs with the sternum. The ribs are connected to the sternum using joints and synchondrosis. The cartilage of the 1st rib forms synchondrosis with the sternum (Fig. 116). The cartilage of the ribs from the 2nd to the 7th, connecting with the sternum, form sternocostal joints(artt.sternocostales). The articular surfaces are the anterior ends of the costal cartilage and the costal notches of the sternum. Joint capsules are strengthened radiant sternocostal ligaments(ligg. sternocostalia), which grow together with the periosteum of the sternum, form sternum membrane(membrana sterni). The joint of the 2nd rib also has intra-articular sternocostal ligament(lig.sternocostale intraarticulare).
The cartilage of the 6th rib is passionate with the overlying cartilage of the 7th rib. The front ends of the ribs from the 7th to the 9th are connected with each other with their cartilages. Sometimes between the cartilages of these ribs are formed interchondral joints(art. interchondrales).
Rib cage (compages thoracis)is a bone-cartilaginous formation, consisting of 12 thoracic vertebrae, 12 pairs of ribs and sternum, connected by joints and ligaments (Fig. 23). The ribcage has the form of an irregular cone, which distinguishes between the front, back and two side walls, as well as the upper and lower openings (apertures). The anterior wall is formed by the sternum, costal cartilage, back wall - the thoracic vertebrae and the posterior ends of the ribs, and the lateral ones - the ribs. The ribs are separated from each other
Figure: 115.Connections of the ribs with the sternum. Front view. On the left, the anterior part of the sternum and ribs were removed with a frontal cut.
1 - symphysis of the sternum handle, 2 - anterior sternoclavicular ligament, 3 - costoclavicular ligament, 4 - first rib (cartilaginous part), 5 - intra-articular sternocostal ligament, 6 - sternum body (spongy substance), 7 - sternum -costal joint, 8 - costal-cartilaginous joint, 9 - interchondral joints, 10 - xiphoid process of the sternum, 11 - costo-xiphoid ligaments, 12 - symphysis of the xiphoid process, 13 - radiant sternocostal ligament, 14 - sternum membrane, 15 - external intercostal membrane, 16 - costal-sternum synchondrosis, 17 - the first rib (bony part), 18 - clavicle, 19 - sternum handle, 20 - interclavicular ligament.
Figure: 116.Rib cage. Front view.
1 - upper chest opening, 2 - sternum angle, 3 - intercostal spaces, 4 - costal cartilage, 5 - rib body, 6 - xiphoid process, 7 - XI rib, 8 - XII rib, 9 - lower chest aperture, 10 - sub-sternal angle, 11 - costal arch, 12 - false ribs, 13 - true ribs, 14 - sternum body, 15 - sternum handle.
intercostal spaces (spatium intercostale). Top hole (aperture) chest(apertura thoracis superior) limited 1st chest vertebra, the inner edge of the first ribs and the upper edge of the sternum handle. Lower chest aperture(apertura thoracis inferior) is bounded behind by the body of the XII thoracic vertebra, in front by the xiphoid process of the sternum, and on the sides by the lower ribs. The antero-lateral edge of the lower aperture is called costal arch(arcus costalis). The right and left costal arches in front limit sub-sternal angle(angulus infrasternialis), open downwards.
Bone joints upper limb (juncturae membri superioris)subdivided into the joints of the upper limb girdle (sternoclavicular and acromioclavicular joints) and joints of the free part of the upper limb.
Sternoclavicular joint (art. sterno-clavicularis) is formed by the sternal end of the clavicle and the clavicular notch of the sternum, between which there is an articular disc fused with the joint capsule (Fig. 117). The joint capsule is strengthened by the anterior and posterior sternoclavicular ligaments(ligg.sternoclavicularia anterior et posterior). Stretched between the sternal ends of the clavicle interclavicular ligament(lig. interclaviculare). The joint is also strengthened by the extracapsular costoclavicular ligament, which connects the sternal end of the clavicle and the upper surface of the 1st rib. In this joint, it is possible to raise and lower the clavicle (around the sagittal axis), move the clavicle (acromial end) forward and backward (around the vertical axis), rotate the clavicle around the frontal axis, and circular motion.
Acromioclavicular joint (art. acromioclavicularis) is formed by the acromial end of the clavicle and the articular surface of the acromion. The capsule is fortified acromioclavicular
Fig. 117.The sternoclavicular joint. Front view. On the right, the joint was opened by a frontal incision. 1 - interclavicular ligament, 2 - sternal end of the clavicle, 3 - first rib, 4 - costoclavicular ligament, 5 - anterior sternoclavicular ligament, 6 - costal cartilage of the first rib, 7 - sternum handle, 8 - spongy substance of the sternum , 9 - costal-sternal synchondrosis, 10 - synchondrosis of the first rib, 11 - articular disc, 12 - articular cavities of the sternoclavicular joint.
bundle(lig.acromioclaviculare), stretched between the acromial end of the clavicle and the acromion. Near the joint is a powerful coracoclavicular ligament(lig.coracoclaviculare), connecting the surface of the acromial end of the clavicle and the coracoid process of the scapula. In the acromioclavicular joint, movements relative to three axes are possible.
Between the individual parts of the scapula, there are ligaments that are not directly related to the joints. The coracoacromial ligament is stretched between the apex of the acromion and the coracoid process of the scapula, the superior transverse ligament of the scapula connects the edges of the notch of the scapula, turning it into an opening, and the inferior transverse ligament of the scapula connects the base of the acromion and the posterior edge of the glenoid cavity of the scapula.
The joints of the free part of the upper limb connect the bones of the upper limb with each other - the scapula, humerus, bones of the forearm and hand, form joints of various sizes and shapes.
Shoulder joint (art. humeri)formed by the glenoid cavity of the scapula, which is complemented at the edges by the articular lip, and the spherical head of the humerus (Fig. 118). The articular capsule is thin, free, attached to the outer surface of the articular lip and to the anatomical neck of the humerus.
The joint capsule is strengthened from above coracohumeral ligament(lig.coracohumerale), which begins at the base of the coracoid process of the scapula and attaches to the upper
Figure: 118.Shoulder joint, right. Frontal cut.
1 - acromion, 2 - articular lip, 3 - supra-articular tubercle, 4 - articular cavity of the scapula, 5 - coracoid process of the scapula, 6 - superior transverse ligament of the scapula, 7 - lateral angle of the scapula, 8 - subscapular fossa of the scapula, 9 - lateral edge of the scapula, 10 - articular cavity of the shoulder joint, 11 - articular capsule, 12 - long head of the biceps brachii, 13 - humerus, 14 - intertubercular synovial sheath, 15 - head of the humerus, 16 - tendon of the long head of the biceps brachii.
parts of the anatomical neck and to large tubercle humerus. The synovial membrane of the shoulder joint forms protrusions. The intertubular synovial sheath surrounds the tendon of the long head of the biceps brachii, which passes through the articular cavity. The second protrusion of the synovial membrane is the subscapularis tendinous bursa located at the base of the coracoid process.
In the shoulder joint, spherical in shape, flexion and extension, abduction and adduction of the arm, turning the shoulder outward (supination) and inwardly (pronation), circular movements are carried out.
Elbow joint (art. cubiti)formed by the humerus, radius and ulna (complex joint) with a common joint capsule that surrounds three joints: the shoulder-elbow, brachioradial and proximal radial-ulna (Fig. 119). Shoulder-elbow joint(art. humeroulnaris), block-shaped, formed by the connection of the humerus block with the block-shaped notch of the ulna. Shoulder-radius joint(art. humeroradialis), spherical, is the connection of the head of the condyle of the humerus and the glenoid cavity of the radius. Proximal elbow joint(art. radioulnaris), cylindrical, formed by the articular circle of the radius and the radial notch of the ulna.
The articular capsule of the elbow joint is reinforced with several ligaments. Ulnar collateral ligament(lig. collaterale ulnare) begins on the medial epicondyle of the humerus, attaches to the medial edge of the block-shaped notch of the ulna. Radial collateral ligament(lig. collaterale radiale) begins on the lateral epicondyle of the humerus, attaches at the antero-outer edge of the block-shaped notch of the ulna. Annular ligament of the radius(lig. annulare radii) begins at the anterior edge of the radial notch and is attached at the posterior edge of the radial notch, covering (surrounding) the neck of the radial bone.
In the elbow joint, movements around the frontal axis are possible - flexion and extension of the forearm. Around the longitudinal axis in the proximal and in the distal ray-loc-
Figure: 119.Elbow joint (right) and joints of the forearm bones. Front view. 1 - humerus, 2 - joint capsule,
3 - medial epicondyle of the humerus,
4 - block of the humerus, 5 - articular cavity of the elbow joint, 6 - oblique chord, 7 - ulna, 8 - interosseous membrane of the forearm, 9 - distal radioulnar joint, 10 - radius bone, 11 - annular ligament of the radius, 12 - head radius, 13 - the head of the condyle of the humerus.
the joints, the radius is rotated together with the hand (inwardly - pronation, outward - supination).
Connections of the bones of the forearm and hand. The bones of the forearm are connected to each other using discontinuous and continuous connections (Fig. 119). Continuous connection is interosseous membrane of the forearm(membrana interossea antebrachii). It is a strong connective tissue membrane stretched between the interosseous edges of the radius and ulna. Downward from the proximal elbow joint between both bones of the forearm, a fibrous cord is stretched - an oblique chord.
The discontinuous joints of the bones are the proximal (above) and distal radioulnar joints, as well as the joints of the hand. Distal radius-elbow joint(art. radioulnaris distalis) is formed by joining the articular circumference of the ulna and the ulnar notch of the radius (Fig. 119). The articular capsule is free, attached along the edge of the articular surfaces. The proximal and distal radial-elbow joints form a combined cylindrical joint. In these joints, the radius, together with the hand, rotates around the ulna (longitudinal axis).
Wrist joint (art. radiocarpea), complex in structure, elliptical in shape, is a connection of the bones of the forearm with the hand (Fig. 120). The joint is formed by the carpal articular surface of the radius, the articular disc (from the medial side), as well as the scaphoid, lunate and triangular bones of the hand. The articular capsule is attached along the edges of the articulating surfaces, reinforced with ligaments. Radial collateral ligament of the wrist(lig. collaterale carpi radiale) begins on the styloid process of the radius and is attached to the scaphoid bone. Ulnar collateral ligament of the wrist(lig. collaterale carpi ulnare) goes from the styloid process of the ulna to the triangular bone and to the pisiform bone of the wrist. Palmar-carpal ligament(lig. radiocarpale palmare) goes from the posterior edge of the articular surface of the radius to the first row of the wrist bones (Fig. 121). In the wrist joint, movements are performed around the frontal axis (flexion and extension) and around the sagittal axis (abduction and adduction), a circular motion.
The bones of the hand are connected to each other by numerous joints that have articular surfaces of different shapes.
Midcarp joint (art. mediocarpalis) is formed by the articulating bones of the first and second rows of the wrist (Fig. 120). This joint is complex, the joint space has an S-inverse shape, continues into the joint spaces between the individual bones of the wrist and communicates with the carpometacarpal joints. The articular capsule is thin and is attached along the edges of the articular surfaces.
Intercarpal joints (art. intercarpales) are formed by the adjacent wrist. Joint capsules are attached at the edges of the articulating surfaces.
The mid-carpal and intercarpal joints are inactive, strengthened by many ligaments. Radial ligament of the wrist(lig. carpi radiatum) goes on the palmar surface of the capitate bone to the adjacent bones. The adjacent wrist bones also connect the palmar intercarpal ligaments and the dorsal intercarpal ligaments.
Carpometacarpal joints (artt. carpometacarpales) (2-5 metacarpal bones), flat in shape, have a common joint space, inactive. The articular capsule is reinforced by the dorsal carpal-metacarpal and palmar carpal-metacarpal ligaments, which are stretched between the bones of the wrist and hand (Fig. 121). Carpometacarpal joint of the thumb bone(art. carpometacarpalis pollicis) is formed by the saddle articular surfaces of the trapezoid bone and the base of the 1st metacarpal bone.
Intercarpal joints (artt. intermetacarpales) are formed by the adjacent lateral surfaces of the bases of 2-5 metacarpal bones. The joint capsule in the intercarpal and wrist
Figure: 120.Joints and ligaments of the hand. Palmar view.
1 - distal radioulnar joint, 2 - ulnar collateral ligament of the wrist, 3 - pisiform-hook-shaped ligament, 4 - pisiform-metacarpal ligament, 5 - hook of the hook-shaped bone, 6 - palmar carpometacarpal ligament, 7 - palmar metacarpal metacarpal ligaments, 8 - ligaments, 9 - metacarpophalangeal joint (opened), 10 - fibrous sheath of the tendons of the fingers of the hand (opened), 11 - interphalangeal joints (opened), 12 - deep flexor muscle tendon of the fingers, 13 - muscle tendon - superficial flexor of the fingers, 14 - collateral ligaments, 15 - carpometacarpal joint of the thumb of the hand, 16 - capitate bone. 17 - radial ligament of the wrist, 18 - radial collateral ligament of the wrist, 19 - palmar wrist ligament, 20 - lunate bone, 21 - radius, 22 - interosseous membrane of the forearm, 23 - ulna.
common metacarpal joints. The intercarpal joints are reinforced with transversely located dorsal and palmar metacarpal ligaments.
Metacarpophalangeal joints (artt. metacarpophalangeae), from the 2nd to the 5th, are spherical in shape, and the 1st is block-shaped, formed by the bases of the proximal phalanges of the fingers and the articular surfaces of the heads of the metacarpal bones (Fig. 121). Joint capsules are attached at the edges of the articular surfaces, reinforced with ligaments. On the palmar side, the capsules are thickened due to the palmar ligaments, on the sides - by collateral ligaments. Deep transverse metacarpal ligaments are stretched between the heads of the 2nd to 5th metacarpal bones. Therefore, movements in them are possible around the frontal axis (flexion and extension) and around the sagittal axis (abduction and adduction), small circular movements. In the metacarpophalangeal joint of the thumb of the hand - only flexion and extension
Interphalangeal joints of the hand (artt. interphalangeae manus) are formed by the heads and bases of the adjacent phalanges of the fingers of the hand, block-shaped in shape. The joint capsule strengthens
Figure: 121.Joints and ligaments of the hand, right. Longitudinal cut.
1 - radius, 2 - wrist joint, 3 - navicular bone, 4 - radial collateral ligament of the wrist, 5 - trapezium bone, 6 - trapezius bone, 7 - carpometacarpal joint of the thumb, 8 - carpometacarpal joint, 9 - metacarpal bones. 10 - interosseous metacarpal ligaments, 11 - intercarpal joints, 12 - capitate bone, 13 - hook bone, 14 - triangular bone, 15 - lunate bone, 16 - ulnar collateral ligament of the wrist, 17 - articular disc of the wrist joint, 18 - distal ray of the elbow , 19 - saccular depression, 20 - ulna, 21 - interosseous membrane of the forearm.
lena palmar and collateral ligaments. In the joints, movements are possible only around the frontal axis (flexion and extension)
Lower limb joints
Bone joints lower limbs subdivided into the joints of the bones of the girdle of the lower limbs and the free part of the lower limb. The joints of the girdle of the lower extremities include the sacroiliac joint and the pubic symphysis (Fig. 122 A).
Sacroiliac joint (articulatio sacroiliaca)formed by the auricular surfaces of the pelvic bone and sacrum. The articular surfaces are flattened, covered with thick fibrous cartilage. In the shape of the articular surfaces, the sacroiliac joint is flat, the articular capsule is thick, tightly stretched, attached along the edges of the articular surfaces. The joint is reinforced with strong ligaments. Anterior sacroiliac ligament(lig. sacroiliacum anterius) connects the front edges of the articulating surfaces. The back of the capsule is reinforced posterior sacroiliac ligament(lig.sacroiliacum posterius). Interosseous sacroiliac ligament(lig.sacroiliacum interosseum) connect both articulating bones. Movement in the sacroiliac joint is as limited as possible. The joint is stiff. The lumbar spine is connected to the ilium ilio-lumbar ligament(lig. iliolumbale), which begins on the anterior side of the transverse processes of the IV and V lumbar vertebrae and attaches to the posterior iliac crest and to the medial surface of the wing of the ilium. The pelvic bones are also connected to the sacrum using two
Figure: 122A.Joints and ligaments of the pelvis. Front view.
1 - IV lumbar vertebra, 2 - intertransverse ligament, 3 - anterior sacroiliac ligament, 4 - ilium, 5 - sacrum, 6 - hip joint, 7 - greater trochanter of the femur, 8 - pubic-femoral ligament, 9 - pubic symphysis, 10 - lower pubic ligament, 11 - superior pubic ligament, 12 - obturator membrane, 13 - obturator canal, 14 - descending part of the ilio-femoral ligament, 15 - transverse part of the ilio-femoral ligament, 16 - ischial foramen magnum, 17 - inguinal ligament, 18 - upper anterior iliac spine, 19 - lumbar-iliac ligament.
powerful extra-articular ligaments. Sacro-tuberous ligament(lig. sacrotuberale) goes from the ischial tuberosity to the lateral edges of the sacrum and coccyx. Sacrospinous ligament(lig. sacrospinale) connects the ischial spine with the sacrum and coccyx.
Pubic symphysis (symphysis pubica)formed by the symphysial surfaces of the two pubic bones, between which is located interpubic disc(discus interpubicus), which has a narrow slit cavity located sagittally. The pubic symphysis is reinforced with ligaments. Superior pubic ligament(lig. pubicum superius) is located transversely upward from the symphysis, between both pubic tubercles. Arcuate pubic ligament(lig. arcuatum pubis) is adjacent to the symphysis from below, passes from one pubic bone to another.
Pelvis (pelvis)formed by the connecting pelvic bones and sacrum. It is a bone ring, which is a receptacle for many internal organs (Fig. 122 B). The pelvis is divided into two sections - the large and small pelvis. Big pelvis(pelvis major) is limited from the lower pelvis by a border line that passes through the promontory of the sacrum, then along the arcuate line of the ilium, the crest of the pubic bones and the upper edge of the pubic symphysis. The large pelvis is bounded behind by the body of the V lumbar vertebra, from the sides - by the wings of the iliac bones. In front of a large pelvis bone wall does not have. Small pelvis(pelvis minor) from behind is formed by the pelvic surface of the sacrum and the ventral surface of the coccyx. On the side, the walls of the pelvis are the inner surface of the pelvic bones (below the boundary line), sacrospinous and sacro-tuberous ligaments. The front wall of the small pelvis is the upper and lower branches of the pubic bones, and the front is the pubic symphysis. Small pelvis
Figure: 122B.The pelvis is female. Front view.
1 - sacrum, 2 - sacroiliac joint, 3 - large pelvis, 4 - small pelvis, 5 - pelvic bone, 6 - pubic symphysis, 7 - subpubic angle, 8 - obturator opening, 9 - acetabulum, 10 - border line ...
Figure: 123.Hip joint, right. Frontal cut.
1 - acetabulum, 2 - articular cavity, 3 - ligament of the femoral head, 4 - transverse ligament of the acetabulum, 5 - circular zone, 6 - ischium, 7 - femoral neck, 8 - greater trochanter, 9 - articular capsule, 10 - the acetabulum, 11 - the head of the femur, 12 - the ilium.
has an inlet and outlet. The superior aperture (hole) of the small pelvis is at the level of the boundary line. The exit from the small pelvis (lower aperture) is limited behind by the coccyx, on the sides - by the sacral-tuberous ligaments, the branches of the ischial bones, the ischial tubercles, the lower branches of the pubic bones, and in front - by the pubic symphysis. The obturator opening located in the side walls of the small pelvis is closed with an obturator membrane. On the lateral walls of the small pelvis there are large and small sciatic openings. The sciatic foramen magnum is located between the sciatic major notch and the sacrospinal ligament. The lesser sciatic foramen is formed by the lesser sciatic notch, sacro-tuberous and sacrospinous ligaments.
Hip joint (art. coxae), spherical in shape, formed by the lunate surface of the acetabulum of the pelvic bone, enlarged by the acetabulum and the head of the femur (Fig. 123). Above the notch of the acetabulum, the transverse ligament of the acetabulum is thrown. The articular capsule is attached along the edges of the acetabulum, on the femur in front - on the intertrochanteric line, and behind - on the intertrochanteric crest. The joint capsule is strong, reinforced with thick ligaments. In the thickness of the capsule is a bundle - circular area(zona orbicularis), covering the neck of the femur in a loop. Iliofemoral ligament(lig.iliofemorale)
is located on the front side of the hip joint, it begins on the inferior anterior iliac spine and attaches to the intertrochanteric line. Pubic-femoral ligament(lig. pubofemorale) goes from the superior branch of the pubic bone to the intertrochanteric line on the femur. The ischio-femoral ligament (lig. Ischiofemorale) begins on the body of the ischium and ends at the trochanteric fossa of the greater trochanter. In the joint cavity there is a ligament of the femoral head (lig. Capitis femoris), connecting the fossa of the head and the bottom of the acetabulum.
In the hip joint, flexion and extension are possible - around the frontal axis, abduction and adduction of the limb - around the sagittal axis, outward (supination) and inward (pronation) turns - relative to the vertical axis.
Knee joint (art.genus),a large and complex joint, formed by the femur, tibia and patella (Fig. 124).
Inside the joint there are semilunar-shaped intra-articular cartilages - lateral and medial menisci (meniscus lateralis et meniscus medialis), the outer edge of which is spliced
Figure: 124.Knee joint, right. Front view. The joint capsule is removed. The patella is down. 1 - patellar surface of the femur, 2 - medial condyle of the femur, 3 - posterior cruciate ligament, 4 - anterior cruciate ligament, 5 - transverse knee ligament, 6 - medial meniscus, 7 - tibial collateral ligament, 8 - tibia, 9 - patella, 10 - tendon of the quadriceps femoris muscle, 11 - patellar ligament, 12 - head of the fibula, 13 - tibiofibular joint, 14 - tendon of the biceps femoris, 15 - lateral meniscus, 16 - fibular collateral ligament, 17 - lateral condyle of the femur.
with a joint capsule. The inner thinned edge of the meniscus is attached to the condylar elevation of the tibia. The front ends of the menisci are connected transverse knee ligament(lig. transversum genus). The knee joint capsule is attached to the edges of the articular surfaces of the bones. The synovial membrane forms several intra-articular folds and synovial bursae.
The knee joint is reinforced with several strong ligaments. Peroneal collateral ligament(lig. collaterale fibulare) goes from the lateral epicondyle of the femur to the lateral surface of the fibular head. Tibial collateral ligament(lig. collaterale tibiale) begins on the medial epicondyle of the femur and attaches to the upper part of the medial edge of the tibia. On the back of the joint is located oblique popliteal ligament(lig. popliteum obliquum), which begins medially
the edge of the medial condyle of the tibia and is attached to the posterior surface of the femur, above its lateral condyle. Arcuate popliteal ligament(lig. popliteum arcuatum) begins on the posterior surface of the head of the fibula, bends medially and attaches to the posterior surface of the tibia. In front, the joint capsule is strengthened by the tendon of the quadriceps femoris muscle, which is called patellar ligament(lig. patellae). There are cruciate ligaments in the cavity of the knee joint. Anterior cruciate ligament(lig. cruciatum anterius) begins on the medial surface of the lateral condyle of the femur and attaches to the anterior intercondylar field of the tibia. Posterior cruciate ligament(lig. cruciatum posterius) stretched between the lateral surface of the medial condyle of the femur and the posterior intercondylar field of the tibia.
The knee joint is complex (contains menisci), condylar. Flexion and extension occur in it around the frontal axis. When the lower leg is bent, the lower leg can be rotated outward (supination) and inward (pronation) around the longitudinal axis.
Shin bone joints. The bones of the lower leg are connected using the tibiofibular joint, as well as continuous fibrous joints - the tibiofibular syndesmosis and the interosseous membrane of the lower leg (Fig. 125).
Tibiofibular joint (art. tibiofibularis)formed by the articulation of the articular peroneal surface of the tibia and the articular surface of the head of the fibula. The articular capsule is attached along the edge of the articular surfaces, reinforced by the anterior and posterior ligaments of the fibular head.
Tibiofibular syndesmosis (syndesmosis tibiofibularis)formed by the peroneal notch of the tibia and the rough surface of the base of the lateral malleolus of the fibula. Anterior and posterior tibiofibular syndesmosis is strengthened by the anterior and posterior tibiofibular ligaments.
Figure: 125.Shin bone joints. Front view. 1 - proximal epiphysis of the tibia, 2 - diaphysis (body) of the tibia,
3 - distal epiphysis of the tibia,
4 - medial malleolus, 5 - lateral ankle, 6 - anterior tibiofibular ligament, 7 - fibula, 8 - interosseous membrane of the tibia, 9 - head of the fibula, 10 - anterior ligament of the fibular head.
Interosseous membrane of the lower leg (membrana interossea cruris) - a strong connective tissue membrane stretched between the interosseous edges of the tibia and fibula.
Connections of the bones of the foot. The bones of the foot are connected to the bones of the lower leg (ankle joint) and to each other, form the joints of the bones of the tarsus, bones of the metatarsus, as well as the joints of the toes (Fig. 126).
Figure: 126.Ankle and foot joints. Right, top and front view.
1 - tibia, 2 - ankle joint, 3 - deltoid ligament, 4 - talus, 5 - talonavicular ligament, 6 - bifurcated ligament, 7 - dorsal wedge-navicular ligament, 8 - dorsal metatarsal ligaments, 9 - articular capsule I metatarsophalangeal joint, 10 - articular capsule of the interphalangeal joint, 11 - collateral ligaments, 12 - metatarsophalangeal joints, 13 - dorsal tarsometatarsal ligaments, 14 - dorsal wedge-cuboid ligament, 15 - interosseous talocalcaneal ligament, 16 - calcaneus 17 - lateral talocalcaneal ligament, 18 - anterior talofibular ligament, 19 - calcaneofibular ligament, 20 - lateral malleolus, 21 - anterior tibiofibular ligament, 22 - interosseous membrane of the lower leg.
Ankle joint (art.talocruralis),complex in structure, block-shaped in shape, formed by the tibia and articular surfaces of the talus block, articular surfaces of the medial and lateral ankles. Ligaments are located on the lateral surfaces of the joint (Fig. 127). On the lateral side of the joint are frontand posterior talofibular ligaments(ligg. talofibulare anterius et posterius) and calcaneofibular ligament(lig. calcaneofibulare). They all begin at the lateral ankle. The anterior talofibular ligament goes to the neck of the talus, the posterior talofibular ligament goes to the posterior process of the talus, and the calcaneofibular ligament goes to the outer surface of the calcaneus. On the medial side of the ankle joint is located medial (deltoid) ligament(lig. mediale, seu deltoideum), starting at the medial ankle. This ligament is attached to the dorsum of the scaphoid, to the support, and to the postero-medial surface of the talus. Flexion and extension (relative to the frontal axis) are possible in the ankle joint.
The bones of the tarsus form the subtalar, talocalcaneal-navicular and calcaneal-cuboid, as well as the wedge-navicular and tarsometatarsal joints.
Subtalar joint (art. subtalaris)formed by the junction of the talus articular surface of the calcaneus and the posterior calcaneal articular surface of the talus. The articular capsule is attached to the edges of the articular cartilage. The joint is strengthened lateraland medial talocalcaneal ligaments(ligg. talocalcaneae laterale et mediale).
Figure: 127.The joints and ligaments of the foot in a longitudinal section. View from above.
1 - tibia, 2 - ankle joint, 3 - deltoid ligament, 4 - talus, 5 - talocalcaneal-navicular joint, 6 - scaphoid, 7 - wedge-navicular joint, 8 - interosseous intercliniform ligament, 9 - wedge-shaped bones, 10 - interosseous wedge-metatarsal ligament, 11 - collateral ligaments, 12 - interphalangeal joints, 13 - metatarsophalangeal joints, 14 - interosseous metatarsal ligaments, 15 - tarsometatarsal joints, 16 - cuboid bone, 17 - calcaneo-cuboid joint, 18 - bifurcated ligament, 19 - interosseous talocalcaneal ligament, 20 - lateral ankle, 21-interosseous membrane of the lower leg.
Talocalcaneonavicular joint (art.talocalcaneonavicularis) formed by the articular surface of the head of the talus articulating with the scaphoid in front and the calcaneus below. The joint in the form of articular surfaces refers to spherical. The joint is strengthened interosseous talocalcaneal ligament(lig. talocalcaneum interosseum), which is located in the sinus of the tarsus, where it connects the surfaces of the grooves of the talus and calcaneus, plantar calcaneonavicular ligament(lig. colcaneonaviculare plantare), connecting the support of the talus and the lower surface of the scaphoid.
Heel-cuboid joint (art. calcaneocuboidea)formed by the articular surfaces of the calcaneus and cuboid bones, saddle-shaped in shape. The joint capsule is attached along the edge of the articular cartilage, taut. The joint strengthens long plantar ligament(lig. plantare longum), which begins on the lower surface of the calcaneus, fan-shaped anteriorly and attaches to the bases of the 2nd to 5th metatarsal bones. Plantar calcaneo-cuboid ligament(lig. calcaneocuboidea) connects the plantar surfaces of the calcaneus and cuboid bones.
The calcaneo-cuboid joint and the talonavicular joint (part of the talocalcaneonavicular joint) form a combined transverse tarsal joint (art.tarsi transversa),or Choparov joint, which has common bifurcated ligament(lig. bifurcatum), consisting of the calcaneonavicular and calcaneal-cuboid ligaments, which begin at the upper-lateral edge of the calcaneus. The calcaneonavicular ligament is attached to the postero-lateral edge of the scaphoid, the calcaneal-cuboid ligament to the rear of the cuboid bone. In this joint, movements are possible: flexion - pronation, extension-supination of the foot.
Wedge-navicular joint (art.cuneonavicularis)formed by the flat articular surfaces of the scaphoid and three sphenoid bones. The articular capsule is attached along the edges of the articular surfaces. These joints are strengthened by the dorsal, plantar and interosseous ligaments of the tarsus. Movement in the wedge-navicular joint is limited.
Tarsus-pus joints (artt.tarsometatarsales)formed by cuboid, sphenoid and metatarsal bones. The articular capsules are stretched along the edges of the articulating surfaces. The joints are reinforced with the dorsal and plantar tarsometatarsal ligaments. The interosseous wedge-metatarsal ligaments connect the sphenoid bones to the metatarsal bones. The interosseous metatarsal ligaments connect the bases of the metatarsal bones. Movement in the tarsometatarsal joints is limited.
Intermetatarsal joints (artt. intermetatarsales)formed by the bases of the metatarsal bones facing each other. The articular capsules are reinforced with transversely located dorsal and plantar metatarsal ligaments. There are interosseous metatarsal ligaments between the articular surfaces facing each other in the articular cavities. Movement in the intermetatarsal joints is limited.
Metatarsophalangeal joints (artt. metatarsophalangeae),spherical, formed by the heads of the metatarsal bones and the bases of the proximal phalanges of the fingers. The articular surfaces of the phalanges are almost spherical, the articular fossa are oval. The joint capsule on the sides is reinforced with collateral ligaments, from below - with plantar ligaments. The heads of the metatarsal bones are connected by a deep transverse metatarsal ligament. In the metatarsophalangeal joints, flexion and extension of the fingers relative to the frontal axis is possible. Around the sagittal axis, abduction and adduction are possible within small limits.
Interphalangeal joints of the foot (artt. interphalangeae pedis), block-shaped, formed by the base and the head of the adjacent phalanges of the toes. The articular capsule of each interphalangeal joint is reinforced with plantar and collateral ligaments. In the interphalangeal joints, flexion and extension are performed around the frontal axis.
Continuous joints have great elasticity, strength and, as a rule, limited mobility. Depending on the type of tissue connecting the bones, there are three types of continuous connections:
1) fibrous joints,
2) synchondrosis (cartilage joints)
3) bone joints.
Fibrous joints
Articulationes fibrosae, are strong joints of bones with dense fibrous connective tissue. Three types of fibrous joints have been identified: syndesmosis, sutures and hammering.
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Types of bone joints (diagram).
A-joint. B-syndesmosis. B-synchondrosis. G-symphysis (hemiarthrosis). 1 - periosteum; 2 - bone; 3 - fibrous connective tissue; 4 - cartilage; 5 - synovial membrane; 6- fibrous membrane; 7 - articular cartilage; 8-articular cavity; 9-slit in the interpubic disc; 10-interpubic disc.
Syndesmosis, syndesmosis, is formed by connective tissue, the collagen fibers of which grow together with the periosteum of the connecting bones and pass into it without a clear border. Syndesmosis includes ligaments and interosseous membranes. Ligaments, ligamenta, are thick bundles or plates formed by dense fibrous connective tissue. Most of the ligaments are thrown from one bone to another and reinforce the discontinuous joints (joints) or act as a brake that limits their movement. In the spinal column, there are ligaments formed by elastic connective tissue that has a yellowish color. Therefore, such ligaments are called yellow, ligamenta flaua. The yellow ligaments are stretched between the arches of the vertebrae. They stretch when the spinal column is flexed anteriorly (flexion of the spine) and, due to their elastic properties, are shortened again, contributing to the extension of the spinal column.
Interosseous membranes, membranae interosseae, are stretched between the diaphysis of long tubular bones. Often interosseous membranes, ligaments serve as the starting point for muscles.
A seam, sutura, is a type of fibrous junction in which there is a narrow connective tissue layer between the edges of the connecting bones. The connection of bones with sutures occurs only in the skull. Depending on the configuration of the edges of the connecting bones, a dentate suture, sutura serrata, is distinguished; scaly suture, sutura squamosa, and flat suture, sutura plana. At the jagged suture, the serrated edges of one bone fit into the spaces between the teeth of the edge of the other bone, and the interlayer between them is the connective tissue. If the connecting edges of flat bones have obliquely cut surfaces and are superimposed on each other in the form of scales, then a scaly seam is formed. In flat seams, using a thin connective tissue layer, the smooth edges of two bones are connected.
A special type of fibrous joint is hammering, gomphosis (for example, dentoalveolar joint, articulatio dentoalueolaris). This term denotes the connection of the tooth with the bone tissue of the dental alveoli. Between the tooth and the bone there is a thin layer of connective tissue - the periodontium, periodontum.
Synchondrosis, synchondroses, are joints of bones using cartilage tissue. Such joints are characterized by strength, low mobility, elasticity, due to the elastic properties of cartilage. The degree of bone mobility and the amplitude of springy movements in such a joint depend on the thickness and structure of the cartilaginous layer between the bones. If the cartilage between the connecting bones exists throughout life, then such synchondrosis is permanent. In cases where the cartilaginous layer between the bones persists until a certain age (for example, sphenoid-occipital synchondrosis), this is a temporary connection, the cartilage of which is replaced by bone tissue. Such a joint replaced by bone tissue is called a bone joint - synostosis, synostosis (BNA).
INTERRUPTED OR SYNOVIAL BONE CONNECTIONS (JOINTS)
Synovial joints (joints),
articulationes synoviales are the most advanced types of bone connections. They are distinguished by great mobility, a variety of movements. Each joint includes the articular surfaces of the bones, covered with cartilage, the joint capsule, the joint cavity with a small amount of synovial fluid. In some joints, there are also auxiliary formations in the form of articular discs, menisci and articular lip.
The articular surfaces, fades articulares, in most cases of the articulating bones correspond to each other - they are congruent (from Latin congruens - corresponding, coinciding). If one articular surface is convex (articular head), then the second, articulating with it, is equally concave (articular cavity). In some joints, these surfaces do not correspond to each other either in shape or in size (incongruent).
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There are three types of bone joints.
- Continuous joints in which there is a layer of connective tissue or cartilage between the bones. There is no gap or cavity between the connecting bones.
- Discontinuous joints, or joints (synovial joints), are characterized by the presence of a cavity between the bones and the synovial membrane lining the joint capsule from the inside.
- Symphysis, or semi-joints, have a small gap in the cartilaginous or connective tissue layer between the connecting bones (transitional form from continuous connections to discontinuous).
Continuous connections
have great elasticity, strength and, as a rule, limited mobility. Depending on the type of tissue connecting the bones, there are three types of continuous connections:
1) fibrous joints, 2) synchondrosis (cartilage joints) and
3) bone joints.
Fibrous joints
articulationes fibrosae, are strong joints of bones with dense fibrous connective tissue. There are three types of fibrous joints: syndesmosis, sutures and hammering.
Syndesmosis, syndesmosis, is formed by connective tissue, the collagen fibers of which grow together with the periosteum of the connecting bones and pass into it without a clear border. Syndesmosis includes ligaments and interosseous membranes.
Ligaments, ligamenta, are thick bundles or plates formed by dense fibrous connective tissue.
Interosseous membranes, membranae interosseae, are stretched between the diaphysis of long tubular bones. Often, interosseous membranes, ligaments serve as the starting point for muscles.
A seam, sutura, is a type of fibrous junction in which there is a narrow connective tissue layer between the edges of the connecting bones. The connection of bones with sutures occurs only in the skull. Depending on the configuration of the edges of the connecting bones, a dentate suture, sutura serrata, is distinguished; scaly suture, sutura squamosa, and flat suture, sutura plana.
A special type of fibrous joint is hammering, gomphosis (for example, dentoalveolar joint, articulatio dentoalveolaris). This term denotes the connection of the tooth with the bone tissue of the dental alveoli. Between the tooth and the bone there is a thin layer of connective tissue - the periodontium, periodontum.
Synchondrosis, synchondroses, are joints of bones using cartilage tissue. Such joints are characterized by strength, low mobility, elasticity due to the elastic properties of cartilage. The degree of bone mobility and the amplitude of springy movements in such a joint depend on the thickness and structure of the cartilaginous layer between the bones. If the cartilage between the connecting bones exists throughout life, then such synchondrosis is permanent.
In cases where the cartilaginous layer between the bones persists until a certain age (for example, sphenoid-occipital synchondrosis), this is a temporary connection, the cartilage of which is replaced by bone tissue. Such a bone-replaced joint is called a bone joint - synostosis, synostosis (BNA).
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