The structure of joints and classification of connections of bones: characteristics of the main joints
The structure and functions of joints and bones: a detailed breakdown with pictures and videos
Perfection slides for thoughtlessness movements
When you see in the «Minute of fame» next «snake woman», recoiling his body almost in pigtails, you know that the standard for the rest of the people the structure of joints and bones is not about her. What about the dense tissues may be involved – there are none!
However, even she has a hard tissue are the place to be – lots of joints, bones, and structures in their compounds, according to the classification divided into several categories.
Classification of bones
There are several types of bones based on their shape.
Bones tubular shape having a cavity inside the bone marrow and formed of compact and spongy substances that perform support, protection and movement role. Divided into:
- long (bones of the shoulders, forearms, thighs, shins), having epifizarnah the nature of ossification;
- short (both Zapata bone, hocks, finger phalanges) with monopolisers type of ossification.
Bone spongy structure, with a predominance in the mass of spongy substance with a small thickness of the covering layer of compact substance. Also divided into:
- long (including the rib and the sternum);
- short (bones of the vertebral, carpal, tarsal).
To this category belong education sesamoid bone, placed near the joints involved in strengthening them and facilitate their activities with a skeleton close connection is not available.
Flat bones form, including the categories:
- flat skull (frontal and parietal), which plays a role of protection and formed from two outer plates of compact substance is located between them a layer of spongy substance with connective tissue origin;
- flat bones both zones of the limbs (shoulder and pelvic) with a predominance in the structure of the spongy substance, performing the role of support and protection, the Genesis of cartilage.
Mixed bones (Endermologie and endochondral) Genesis with a different structure and objectives:
- forming the base of the skull;
- the clavicular.
Bones do not live by themselves – they are connected to each other by joints, the most ingenious of ways: two, three, from different angles, with varying degrees of slip on each other. Allowing our body provided incredible freedom static and dynamic postures.
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But not all bone connections should be considered tartratami.
According to the classification of connections of bones to those not include the following types of articulation:
- continuous (also called adhesions or synarthroses);
The first gradation is:
- synostosis — fusion boundaries between bones to complete immobility, a zigzag «lightning» sutures in the skull;
- synchondrosis — splicing through the cartilage layer, for example, the intervertebral disc;
- SYNDESMOS — durable stitching connective tissue structure, the interosseous sacroiliac ligament, for example;
- ensarkos — when you connect the bones with the help of muscle layer.
Tendinous membrane, stretched between the paired entities forearms and shins, dead holding them next to each other, joints are not.
As well as the connection polupodvizhnym (gemartrozy) in the face of the pubic symphysis (inferior) cavity-a slit in the thickness of the fibro-cartilage of the seam, or in the form of Sacro-podgornyh of amphiarthroses with these articular surfaces, but with the extreme limited range of motion in poluustav.
The structure and function
Joint (discontinuous or synovial joint) can only be considered having all the necessary attributes of a movable articulation of bones.
To all desertrose could move in them in certain places there are special education and auxiliary elements.
If a dice is a head with a pronounced roundness in the form of thickening of the epiphysis of the end of the division, coupled with it another is exactly corresponding in size and shape of the recess, sometimes significant (such in the pelvic bone in the vastness called «the cruet»). But can exist and the articulation of one bone head structure on the body-the shaft of the other, as in the radioulnar joint.
In addition to perfect match each other shapes that form the joint, their surface covered with a thick layer of hyaline cartilage with a literally mirror-smooth surface for perfect glide each other.
But smoothness is not enough – the joints should not disintegrate into its component parts. Therefore, it is surrounded by dense connective tissue elastic cuff – bag-capsule similar to the ladies Muff handwarmer in the winter. In addition, his bond is different the power of ligaments and muscle tone, providing biodynamic equilibrium in the system.
A sign of true desertrose is the existence of a proper joint cavity filled with synovial fluid produced by the cartilage cells.
The classical and most simple structure is a shoulder. This is the gap of the joint between his bag and the two bone endings, with surfaces: the round head of the humerus and coincident with it the configuration of the glenoid cavity on the scapula, filled with synovial fluid, plus the ligaments that hold the entire structure together.
Other desertrose have a more complex structure in the wrist, every bone in contact with several neighbors.
The spine, as a special case
But the special complexity of the different relationships between the vertebrae – the bones of short columnar, with a complex surface topography and a variety of structures for different degrees of rolling adhesion with adjacent formations.
The spine has a structure that resembles beads, only the «beads» it is the body of each of the adjacent bones, which are connected among themselves by means of hemarthrosis (synchondrosis) on the basis of the cartilage matrix. Their spinous processes, overlapping each other like shingles, and the arms forming the receptacle for the spinal cord, are fastened by means of tough ligaments.
The joints between the transverse processes of the vertebrae with flat surfaces (as well as rib-vertebral, formed through the rib head and articular depressions on the vertebral bodies, situated laterally) is quite real, having all of the required attributes are: working surfaces, cracks, capsules and ligaments.
In addition to the compounds with each other and with the ribs, the vertebrae form a fusion in the area of the sacrum, which turns this group into a monolith, through which these joints attached «tail»-the coccyx – education is quite moving, especially in the childbirth process.
The sacroiliac desertrose are the beginning of the pelvic girdle, formed by the bones of the same name, on the front closes into a ring with the pubic symphysis.
In addition to spinal disc in the system pillar there are other joints: combination that forms one unpaired and two paired component joints of the Atlanto-axial (between the first and second vertebrae) and the paired Atlanto-occipital (between the first vertebra and the occipital bone).
Due to this structure of the spine is education is incredibly flexible, with a greater degree of freedom of movement and at the same time exceptionally strong, bearing the brunt of the body. Apart from the function reference it performs a protective role, serving as a channel in which runs the spinal cord, and is involved in hematopoiesis.
Range of defeat of the joints of the vertebrae varied from injury (with different category of fractures and displacements) to the exchange-dystrophic processes leading to various degrees of stiffness of the spine (degenerative disc disease and similar conditions), and infectious lesions (in the form of tuberculosis, syphilis, brucellosis).
The above classification of connections of bones does not include the systematics of the joints, having a few options.
In accordance with the number of articular surfaces there are the following categories:
- simple, with two surfaces, as in the joint between the phalanges of finger I;
- complex with more than two surfaces, for example, in the elbow;
- integrated with the internal structures of the cartilage that divides the cavity in the insulated chamber, as in a knee;
- combined in various combinations isolated from each other joints: temporomandibular connection intra-articular disc divides the working cavity into two separate chambers.
Functions allocate joints with one, two or multiple axes of rotation (one-, two — and multi-axis), depending on the form having the form:
An example of uniaxial joints are:
- cylindrical – Atlanto-axial midline;
- hinge – interphalangeal;
- helical – shoulder-elbow.
Structure of complex shape:
- elliptical as the beam-lateral carpal;
- miscalculating as the knee;
- saddle as the metacarpal-carpal joint of the I finger.
Multi-axis represented by the varieties:
- spherical, like shoulder;
- pan – a deeper variation of the spherical (like a hip);
- flat (as spinal).
There is a separate category tight joints (amphiarthroses) having different shapes of surfaces, but similar in another – they are extremely logopedija due to the strong tension of the capsule and very strong ligaments, therefore their sliding displacement relative to each other almost imperceptibly.
Characteristics, structure and function of major joints
With all the abundance of joints in the human skeleton it is most logical to consider them as separate groups – categories of joints:
- of the spine;
- zones of the limbs (upper and lower).
In accordance with this provision in the skeleton the skull consists of two diarthrosis:
- temporal mandibular;
The first of these paired connections created with the participation of heads of the bone of the lower jaw and the working cavities in the temporal bones.
The joint consists of two synchronously functioning, although spaced on opposite sides of the skull formations. Configuration is a condylar, is classified as composite because of the presence of dividing its volume into two isolated from each other camera of the cartilage matrix.
Due to the existence of the diarthrosis possible freedom of movement of the mandible in three planes and participation in the process of primary processing of food, and in swallowing, breathing and the formation of speech sounds. The jaw also serves as a means of protecting the oral cavity against damage and participates in the creation of the relief of the face. Can be injury and infection with the development of acute (mumps) and chronic (tuberculosis, gout) diseases.
Steamy configuration of the Atlanto-occipital condylar region also. It serves for the connection of the skull (occipital bone with its convex surfaces) with the spine by means of two first cervical vertebrae, acting as one, the first of which – Atlanta – there are working pits. Each half of the current synchronous education has its own capsule.
Which is a biaxial Atlant allows you to make head movements of the frontal and sagittal axes – like sternocleidomastoid and tilts left and right, providing the freedom of navigation and the fulfillment of man’s social role.
The basic pathology of the Atlanto-occipital diarthrosis is injured as a result of a sudden throwing back of the head and development of osteoarthritis and other metabolic and degenerative conditions due to the long preservation of a forced posture.
Given the above description of the spine, passing to diarthroses the shoulder girdle, it should be understood that the connection of the clavicle with the sternum and the scapula with the clavicle are synarthroses. These same joints are:
Sharewidget of the humeral head – the key to a nearly full circular freedom of movement for the upper limb, therefore, the shoulder refers to a multiaxial joint. The second component of the mechanism – scapular depression. All other attributes of a diarthrosis is also clear. Shoulder connection is most susceptible to damage (due to the large degrees of freedom), to a much lesser extent, infections.
The complex structure of the elbow caused by the articulation of three bones: humerus, radius and ulna, with a common capsule.
The shoulder-elbow joint – the hinge: the shoulder block is included in the notch of the ulna, shoulder-radiation – the result of the occurrence of the condyle heads of the shoulder in the hole of the head bones of the beam with the formation of the spherical workspace.
Movement in the system are carried out according to two axes: flexion-extension, and also thanks to the participation of the proximal beam-ulnar joints, the possible rotation (pronation and supination), because the head of the beam is rolled along the groove of the ulna.
Problems of the elbow joints are damaged, as well as inflammatory conditions (acute and exacerbation of chronic infections), malnutrition due to sports professionally.
Ray-ulnar distal joint is cylindrical shaped connection that provides vertical rotation of the forearm. In the working chamber there is a disk that separates the signified the connection cavity from the carpal joint.
Disease of the elbow region:
Through the capsule covering the lower epiphysis of the beam and the first row of carpal bones is formed elliptical configuration of the wrist joint. This is a complex articulation with the sagittal and frontal axes of rotation that allow like a Ghost-abstraction brush with circular rotation and extension-flexion.
The most common diseases:
- injuries (bruises, fractures, sprains, dislocations);
- different degrees of severity tunnel syndrome;
- arthritis and arthrosis;
Articulation of small bones of the upper limb is a combination of flat and saddle joints (carpometacarpal) with spherical joints (metacarpophalangeal), and a hinge configuration (interphalangeal joints). This design provides the base of the brush strength and finger – dexterity and flexibility.
The main category of lesions of this area, the polyarthritis of different etiology (rheumatoid to gout and lupus), de quervain disease, as well as a consequence of vascular disorders (Raynaud’s syndrome).
The pelvic girdle
To diarthrosis of the pelvic girdle are:
- the metatarsophalangeal;
Form the hip multi-axis joint is bowl-shaped, with the participation of the femoral head and depression of the sciatic, for applying a diversion hips back and forth and the medial-lateral and rotation.
TZB prone to damage (due to the high degrees of freedom) and lesions of the microbial flora, recorded here most often hematogenous (TB, brucellosis, gonorrhea).
The most common disease of the hip region:
- syndrome femoro-acetabular impingement;
- the Perthes disease.
The knee (hinge) is formed by part of the condyles of the femur and the concave surface of the tibia. In addition to the powerful ligaments support the front creates education sesamoid – the patella.
The inner surface is augmented to full compliance of the articular surfaces of the menisci and ligaments. Available movements are flexion-extension and part of the rotation.
Pathology affecting the knee:
- injuries (especially patellar dislocation);
- knee «mouse».
In creating the ankle (classic ginglymoid) joints involved head-block ramming and cutting formed a «plug» of both tibiae.
The structure of diarthrosis allows to:
- small vertical abstraction-cast (in flexion).
The most frequent disorder of function – broken ankles (external or internal), as well as a violation of metabolic processes in the body and blood circulation in the lower extremities.
Area of the Tarsus formed a «mosaic» of joints:
This connection combined either flat configuration (the first two, cylindrical and spherical).
Preprosto-metatarsal diachrony presents various (mostly flat) joints, forming support for arches of the foot, made joints the metatarsophalangeal (hinge).
Also the trochlear shape interphalangeal joints stop misleading the toes a sufficient level of mobility and flexibility (patients who have lost both hands, paint and even sew the legs) are not at the expense of strength.
The small joints of the foot tend lose due to metabolic-dystrophic processes in the body, disorders of local and General blood supply and due to chronic injuries in the form of wearing shoes with high heels or elementary close.
The existence of different ways of connecting bones, and the diversity of the articular surfaces themselves, understanding their structure and function allows for people to live and act, but also to make the treatment of the musculoskeletal system (and if necessary even to replace worn out artificial structures).