The Volgograd State Medical University Chair for Human Anatomy Lecture: General arthrology Particular anatomy of joints is delivered by: Dr. Elena Vladimirovna Gorelik, PhD

Types of junctions: 1. Continuous junctions in which there is a layer of which there is a layer of connective tissue or cartilage connective tissue or cartilage between bones. between bones. A fissure or a cavity between joining bones is absent.

2. Interrupted junctions or joints (synovial junctions) or joints (synovial junctions) are characterized by the presence of cavity and synovial membrane covering the inside part of joint capsule between the bones.

3. Symphyses (or semijoints) have a little fissure in the have a little fissure in the cartilaginous cartilaginous or connective-tissued layer or connective-tissued layer between the joining bones between the joining bones (a transitional form from continuous junctions to interrupted ones). (a transitional form from continuous junctions to interrupted ones).

Continuous junctions of bones Continuous junctions are more elastic, solid and, as a rule, they have limited mobility. There are: a) fibrous junctions, a) fibrous junctions, b) synchondroses (cartilaginous junctions), b) synchondroses (cartilaginous junctions), c) bony junctions. c) bony junctions.

a) Fibrous junctions, articulationes fibrosae, are solid junctions of bones by means of thick fibrous connective tissue. articulationes fibrosae, are solid junctions of bones by means of thick fibrous connective tissue. There are three types of fibrous junctions: - syndesmoses, - suturae, - suturae, - impaction. - impaction.

Syndesmosis is formed by the connective tissue, its collagenic fibers knit with periosteum and turn into it without a definite border. Syndesmosis is formed by the connective tissue, its collagenic fibers knit with periosteum and turn into it without a definite border. Syndesmosis include ligaments and interosseal membranes. Syndesmosis include ligaments and interosseal membranes.

Ligaments, ligamenta, Ligaments, ligamenta, are thick bundles of thick fibrous connective tissue. are thick bundles of thick fibrous connective tissue. Ligaments are between the bones and they are obstacles that limit movements. In the vertebral column there are ligaments formed by elastic connective tissue of yellowish colour (yellow ligaments, ligamenta flaua). In the vertebral column there are ligaments formed by elastic connective tissue of yellowish colour (yellow ligaments, ligamenta flaua). They are stretched in flexion of the vertebral column forward (flexion of the vertebral column) and then they become shorter again to promote extension of the vertebral column. They are stretched in flexion of the vertebral column forward (flexion of the vertebral column) and then they become shorter again to promote extension of the vertebral column.

Interosseal membranes, Interosseal membranes, membranae interosseae, membranae interosseae, are stretched between the dyaphyses of long tubular bones. Interosseal membranes, ligaments are often served as the basis of muscles.

Suture, sutura, Suture, sutura, is a variety of fibrous junction in which there is a narrow connective-tissued layer between the edges of joining bones. is a variety of fibrous junction in which there is a narrow connective-tissued layer between the edges of joining bones. There is a sutura serrata, a sutura squamosa and a sutura squamosa and a sutura plana depending on configuration of joining bones edges. a sutura plana depending on configuration of joining bones edges.

A particular type of fibrous juncture is impaction (e.g. dentoalveolar juncture, articuldtio dentoalveoldris). This term defines the juncture of a tooth and bony tissue of dental alveolus. There is a thin layer of connective-tissue, periodontium, between a tooth and a bone.

b) Synchondroses are junctions of bones by means of cartilaginous tissue. They are firm and little movable that depends on the thickness and structure of cartilaginous layer between the bones. * If a cartilage between the joining bones exists during the whole life, such synchondroses are constant. * If a cartilage between the joining bones exists during the whole life, such synchondroses are constant. * If a cartilaginous layer between the bones is kept till the definite age (fonticuli), this temporal juncture, a cartilage, is substituted with osseal tissue – c) synostosis. * If a cartilaginous layer between the bones is kept till the definite age (fonticuli), this temporal juncture, a cartilage, is substituted with osseal tissue – c) synostosis.

Interrupted or synovial junctions of bones (joints) They are notable for more mobility, variety of movements. They are notable for more mobility, variety of movements. Every joint includes articular surfaces of bones covered with cartilage, Every joint includes articular surfaces of bones covered with cartilage, articular capsule, articular cavity filled wiyh synovial fluid. Some joints also include lacertus formations such as articular disks, meniscus and glenoid lie. Some joints also include lacertus formations such as articular disks, meniscus and glenoid lie.

In majority of cases in joining bones articular surfaces correspond to each other. They are congruent (lat. congruens means fitting, corresponding). * If one articular surface is convex (articular head), the other one which joins the first one is equally concave (articular cavity). In some joints these surfaces are not either the same shape or size, they are incongruent.

Articular cartilage, cartilage articularis, smoothes roughness of articular surfaces of bones, in motion it amortizes jolts. The bigger exertion the joint has under the action of gravity, the more thickness of articular cartilages becomes. As a rule, articular cartilage is flat, it is constantly moist with synovial fluid which facilitates movements of joints. There are no blood and lymphatic vessels in articular cartilage, its nourishment is implemented by synovial fluid.

Articular capsule, capsula articulаris, is fastened to the joining bones at the edges of articular surfaces; it firmly knits with periosteum, forming isolated articular cavity. * Capsule has two layers: external layer is fibrous membrane, membrana fibrosa (stratum fibrosum), and internal layer is synovial membrane, membrana synouialis (stratum synovidle). In some parts fibrous membrane forms thickenings – capsular ligaments: extracapsular ligaments, intracapsular ligaments.

Synovial membrane covers fibrous membrane inside. Synovial membrane has not big outgrowths turned to the joint cavity - synovial villi – which are rich in blood vessels. They extend its surface. Internal surface of articular capsule (synovial membrane) is always moist with synovial fluid, which removes rubbing of articular surfaces.

Articular cavity, Articular cavity, is a fissural space between articular surfaces. is a fissural space between articular surfaces. It is limited by synovial membrane of articular capsule, it keeps some quantaty of synovial fluid. It is limited by synovial membrane of articular capsule, it keeps some quantaty of synovial fluid. An articular cavity form depends on a form of joining surfaces, presence or absence of lacertus formations inside the joint An articular cavity form depends on a form of joining surfaces, presence or absence of lacertus formations inside the joint (disk, meniscus, intracapsular ligaments). (disk, meniscus, intracapsular ligaments).

Articular disks and menisci are cartilaginous plates of various forms which are located between not fully corresponded to each other (incogruent) articular surfaces. Disk is an entire plate which divides the articular cavity into two chambers (two levels). Menisci are not entire cartilaginous or connective- tissued plates. Disks and menisci are able to be dislocated in motion.

Glenoid lie is at the edge of concave articular surface, it supplements it and makes it deeper. Synovial bursae are diverticula of synovial membrane in thin parts of joint fibrous membrane. Bursae remove rubbing of contiguous tendons and bones.

Biomechanics of joints There are frontal, sagittal and longitudinal (along the joining bones) rotation axes.

On frontal axis flexion (flexio) and extension (extensio) are implemented. In flexion the angle between the joining bones becomes less (e.g. in flexion in the elbow joint the angle between an arm and a forearm becomes less). In extension the angle becomes bigger (up to 180°) and straightening of an extremity or a body occurs.

On sagittal axis adduction (adductio), and abduction (abductio) are implemented. In adduction one of the joining bones approches to the median cavity. In abduction one of the joining bones moves off away from the median cavity.

In rotation (rotаtio) a bone rotates in both directions on its longitudinal axis. Circular motion (circumductio) is a consecutive motion on their axis in which a free end of a moving bone or an extremity (a hand) rotates a round.

Joint classification Simple joint, articulatio simplex, is formed only by two articular surfaces. Compound joint, articulatio composita, is formed by three or more articular surfaces.

Complex joint is characterized by the presence of an articular disk or a meniscus between joining surfaces. Combined joint is introduced by two anatomical isolated joints acting together.

According to the form of articular surfaces there are trochoid, ellipsoidal and spheroid joints. Variations of these joint forms are the following: hinge joint, calix joint and plane joint.

Form of articular surfaces determines number of axes on which there is motion in the given joint: 1) joints with one axis of motion - uniaxial; 2) joints with two axes of motion - biaxial; 3) joints with many axes of motion, three of which are basic -multiaxial, or triaxial.

Uniaxial joints Trochoid joint, articulatio trocholdea. (joining of an atlas with a dens, proximal and distal radioelbow joints). Hinge joint, ginglymus. On the articular surface of cylindrical form there is a bony crest, and on the correspondent articular cavity there is a directing sulcus (interphalangeal joints of a foot and a hand).

Biaxial joints Ellipsoidal joint, articulatio ellipsoidea is a radiocarpal joint which has two axes: frontal axis and sagittal axis. Saddle joint, articulatio sellaris is a joint between a metacarpal bone of the first finger of the hand and the bone-trapezium of the wrist (art. carpometacdrpea pollicis). Condylar articulation, articulatio bicondylaris is motions on two axes (knee joint).

Multiaxial joints Spheroid joint, articulatio spheroidea (humeral articulation). Calex joint, articulatio cotylica (hip joint). Plane joint, articulatio plana Movements in joints are able to rotate on three axes, but their size is limited because of nonconsiderable difference in curvature and sizes of articular surfaces.

Symphysis are fibrous or cartilaginous junctures in the thickness of which there is a small cavity as a narrow fissure. This juncture is not covered with a capsule outside and the inner surface of a fissure is not covered with synovial membrane.

Symphysis Transitional junctures can be strengthened by interosseal ligaments. In these junctures some little dislocations of joining bones relatively to each other are possible (symphysis of manibrium sterni, intervertebral symphyses and pubic symphysis).

Thank you for attention