Introduction to the Articular System PDF

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Introduction to the Articular System....

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Introduction to the Articular System 1. Define the concept of arthology, articulation and kinesiology. ARTROLOGY: Scientific study of the joints. JOINT: Joints are joints between two or more bones or rigid parts of the skeleton. This joint is not only to bring bones in contact, but also to allow mobility and transmission of forces. Junctions exhibit various forms and functions. Some have no movements, others allow small movements and others have free mobility. KINESIOLOGY: Kinesiology is the science that focuses on the analysis of the movements of the human body. The name kinesiology comes from the Greek kinesis = movement + logos = treatise, study.

2. Study the functions of joints. Joints, also called joints, have two main functions: keeping bones together and allowing the skeleton to move. Thanks to the presence of the joints, we have a stable body that can, for example, maintain an upright posture. In addition to ensuring the union of the skeleton, the joints also prevent bone wear.

3. Identify the joints of the human body and the functional and structural classifications. Joints are classified structurally based on anatomical characteristics and functionally according to the type of movement they enable. The structural classification of the joints is based on two criteria: (1) whether or not there is space between the joint bones, called the joint cavity, and (2) the type of connective tissue that joins the bones. From a structural point of view, joints are classified as: Fibrous Joints: There is no joint cavity and bones are held together by dense unmodified connective tissue rich in collagen fibers. The three types of fibrous joints are sutures, syndesmoses and interosseous membranes. Sutures The suture is a fibrous joint composed of a thin layer of dense unmodified connective tissue, sutures occur between the bones of the skull. An example of suture is the coronal suture between the parietal and frontal bones. The irregular and interconnected suture margins provide additional strength and reduce the chances of fracture. Sutures are joints that form as the bones of the skull come into contact with each other during development. They are immobile or discreetly mobile. In older individuals, the sutures are immobile (synarthrosis), but in newborns / infants and children they are discreetly

movable (anfiartroses). Sutures play an important role in absorbing skull impacts. Syndesmoses Syndesmosis is a fibrous joint in which there is a greater distance between the joint faces and more unmodified dense connective tissue than in a suture. Unmodified dense connective tissue is typically arranged as a bundle (ligament), allowing the joint to have limited movement. An example of syndesmosis is tibiofibular (distal) syndesmosis, in which the anterior tibiofibular ligament connects the tibia and fibula). In this joint, there is a slight movement (anfiarthrosis). Another example of syndesmosis is called gonphosis, or dentoalveolar joint. The only examples of gonfoses in the human body are the joints between the roots of the teeth and their alveoli in the jaw or jaw. Dense unmodified connective tissue between the tooth and its socket consists of the periodontium. A healthy gonphosis does not allow movement (synarthrosis). The inflammation associated with gum, periodontal and bone degeneration is called periodontal disease. Interosseous membranes The final category of fibrous joints is the interosseous membrane, which consists of a substantial lamina of dense unmodified connective tissue that connects neighboring long bones and allows discrete movement (anfiarthrosis). There are two major interosseous membrane-like joints in the human body. One occurs between the radius and ulna in the forearm and the other between the tibia and fibula in the leg. Cartilage joints: There is no joint cavity and bones are held together by cartilage, allowing little or no movement. The two types of cartilage joints are: Synchondroses Synchondrosis is a cartilage joint in which the connective material is hyaline cartilage. The epiphysial (growth) lamina that connects the epiphysis and diaphysis of a growing bone is an example of synchondrosis. The shows a photomicrograph of the epiphysial lamina. From a functional point of view, synchondrosis is a motionless joint (synarthrosis). When bone growth ceases, the hyaline cartilage is replaced by bone and synchondrosis becomes a synostosis, that is, a bone joint. Another example of synchondrosis is the joint between the first rib and the sternal manubrium, which also ossifies during adulthood and becomes an immobile synostosis (synarthrosis), or bone joint. Symphyses Symphysis is a cartilage joint in which the ends of the bones of the joint are covered by hyaline cartilage, but a large flat disc of fibrocartilage connects the bones. All symphyses occur in the midline of the body. The pubic symphysis between the anterior faces of the hip bones is an example of this type of joint, also found at the junction of the manubrium and body of the sternum and in the intervertebral joints between the vertebral bodies. A part of the intervertebral

disc is composed of fibrocartilage. The symphysis is a discreetly movable joint (anfiarthrosis) Synovial Joints: The bones that form the joint have joint cavity and are joined by the dense unmodified connective tissue of a joint capsule and often by accessory ligaments. The functional classification of joints is related to the degree of movement they allow. Functionally, the joints are classified as: Synthrosis: a motionless joint Anfiarthrosis: a discreetly movable joint Diarthrosis: a freely movable joint. All diarthroses are synovial joints. They come in many forms and enable many different types of movements.

4. Classify synovial joints according to their form and function. Highlight their respective movements. Synovial joints have certain characteristics that distinguish them from other joints. The unique feature of the synovial joint is the presence of a space called the joint cavity or synovial cavity between the integral bones of the joint. Since the articular cavity allows considerable movement in the joint, all synovial joints are functionally classified as freely movable (diarthrosis). The bones in the synovial joint are covered by a layer of hyaline cartilage called articular cartilage. Cartilage covers the articular faces of bones with a smooth, sliding surface, but does not bind them together. Articular cartilage reduces friction between bones in the joint during movement and helps absorb impacts. The basic criterion for the morphological classification of synovial joints is the shape of the joint surfaces. However, sometimes it is difficult to make this correlation. In addition, there are disagreements among anatomists regarding not only the classification of certain joints, but also regarding the denomination of the types. According to Anatomical Terminology, the morphological types of synovial joints are: · Flat, in which the articular surfaces are flat or slightly curved, allowing one surface to slide in another direction. The acromioclavicular joint (between the scapula acromion and the clavicle) is an example. Slippage exists in all synovial joints but in flat joints it is discrete, causing the range of motion to be greatly reduced. However, it should be noted that small slips between various articulated bones allow for appreciable range and range of motion. This is what happens, for example, in the joints between the short carpal and tarsal bones. · Gingual, or hinge, and the names refer much more to the movement (flexion and extension) they perform than to the shape of the joint surfaces. The elbow joint is a good example of the tingle and the simple observation shows how the humeral articular surface, which comes in contact with the ulna, is in spool form. However, the joints between the phalanges are also of the gingival type and in

them the shape of the articular surfaces does not resemble a spool. This is a concrete case in which the morphological criterion was not strictly obeyed. Performing only flexion and extension, the gingival synovial joints are monoaxial.

· Trochoid, in which the articular surfaces are cylinder segments and, for this reason, cylindroids might be a more appropriate term to designate them. These joints allow rotation and their unique axis of motion is vertical: they are monoaxial. A typical example is the proximal radioulnar joint (between the radius and ulna) responsible for pronation and supination movements of the forearm. In pronation there is a medial rotation of the radius and, in supination, lateral rotation. In anatomical description position the forearm is in supination. Condylar, whose articular surfaces are elliptical in shape. Ellipsoid would perhaps be a more appropriate term. These joints allow flexion, extension, abduction and adduction, but not rotation. They have two axes of movement and are therefore bi-axial. The radio-carpal (or wrist) joint is an example. Others are the temporomandibular joint (TMJ) and the metacarpophalangeal joints. Seal, in which the articular surface of a skeletal part is saddle-shaped, concave in one direction and convexity in another, and fits into a second part where convexity and concave are opposite to the first. The carpal metacarpal joint of the thumb is a typical example. It is interesting to note that this joint allows flexion, extension, abduction, adduction and rotation (consequently also circumduction) but is classified as bi-axial. The fact is justified because the isolated rotation cannot be actively performed by the thumb being only possible with the combination of the other movements. · Spheroid, which has articular surfaces that are ball segments and fit into hollow receptacles. The pen holder, which can be moved in any direction, is a non-anatomical example of a spheroid joint. This type of articulation allows movements around three axes and is therefore tri-axial. Thus, the shoulder joint (between the humerus and scapula) and the hip joint (between the hip bone and femur) allow flexion, extension, adduction, abduction, rotation and circumduction movements.

5. Understand the principles of innervation and vascularization of synovial joints. The synovial joints are very innervated. Nerves are derived from those that supply adjacent skin or muscles that move joints. Pain-sensitive nerve endings are numerous in the fibrous membrane of the capsule and ligaments and are sensitive to the stretching and twisting of these structures. However, the main type of sensitivity is proprioception. From the proprioceptor endings of the capsule - neurotendinous spindles - depart impulses that interpreted in the central nervous system inform about the relative position of the bones of the

joint, the degree and direction of movement. Sometimes this information is unconscious, and works at the level of the spinal cord to control the muscles acting on the joint. Although many of the synovial joint components are avascular, the surrounding arteries send numerous branches that penetrate the ligaments and joint capsule to carry oxygen and nutrients. Veins remove carbon dioxide and joint debris. The arterial branches of the different arteries usually emerge around the joint before penetrating the joint capsule. Chondrocytes in the articular cartilage of a synovial joint receive oxygen and nutrients from the blood-derived synovial fluid, and all other joint tissues are supplied directly by capillaries. Carbon dioxide and waste pass from articular cartilage chondrocytes to synovial fluid and then into veins, carbon dioxide and waste from all other joint structures pass directly into the veins. 6. Conceptualize synovial membrane and synovial fluid. Identify the structure and function of synovial pockets and sheaths. The synovial membrane is the innermost layer of the joint capsule. It is abundantly vascularized and innervated and is responsible for the production of synovial fluid (synovium), which is similar in consistency to egg white and has the function of lubricating and nourishing the articular cartilages. The volume of synovial fluid present in a joint is minimal, just enough to thinly coat the joint surfaces and is located in the joint cavity. In addition to these characteristics, which are common to all synovial joints, in several of them there are fibrocartilaginous formations, interposed to the articular surfaces, the discs and menisci, of function discussed: they would serve the best adaptation of the articulating surfaces (making them congruent). or they were structures designed to receive violent pressures acting as shock absorbers. Menisci, with their characteristic half moon shape, are found in the knee joint. Discs are found in the sternoclavicular and temporomandibular joints. The synovial membrane secretes synovial fluid, a viscous, clear or light yellow liquid, so named for its similarity in appearance and consistency with egg white. Synovial fluid is composed of hyaluronic acid secreted by synovial cells in the synovial membrane and filtered interstitial fluid from blood plasma. It forms a thin film on the surfaces within the joint capsule. Its functions include reducing friction for joint lubrication, shock absorption, oxygen and nutrient supply and removal of carbon dioxide and chondrocyte metabolic waste within the articular cartilage. (Remember that cartilage is avascular tissue, so it has no blood vessels to perform the last function mentioned.) Synovial fluid also contains phagocytic cells that remove microbes and debris from joint wear and tear. When a synovial joint is immobilized for some time, the fluid becomes quite viscous (like a gel), but as joint movement intensifies, the fluid becomes less viscous. One of the benefits of warming up before exercise is the stimulation of the Synovial fluid production and secretion, more fluid means less stress on joints while exercising.

The various movements of the body cause friction between the moving parts. Saciform structures called pockets are strategically placed to relieve friction in some joints, such as the knee and shoulder joints. Pockets are not a strict part of synovial joints, but resemble joint capsules because their walls consist of an outer fibrous membrane of thin dense connective tissue lined with a synovial membrane. A small amount of fluid similar to synovial fluid fills these pockets. The pockets may be located between skin and bones, between tendons and bones, between muscles and bones or between ligaments and bones. The fluidfilled sacs dampen the movement of these body parts against each other. Structures called synovial sheaths also reduce joint friction. Synovial sheaths are tubular pockets, which involve certain tendons that suffer considerable friction when passing through tunnels formed by connective tissue and bone. The inner layer of a synovial sheath, the visceral layer, attaches to the surface of the tendon. The outer layer, known as the parietal layer, is attached to the bone. Between the layers is a cavity that contains a synovial fluid film. The synovial sheath protects all sides of a tendon from friction when it slides. Synovial sheaths are found where tendons pass through synovial cavities, such as the biceps brachii muscle tendon in the shoulder joint. Synovial sheaths are also found on the wrist and ankle, where many tendons come together in a confined space, and on the toes and hands, where a great deal of movement occurs.

7. Identify the structural elements of the synovial joints. Differentiate static and dynamic stabilizers. In addition to the presence of this fluid, synovial joints have three other basic characteristics: articular cartilage, joint capsule, and joint cavity. Articular cartilage is hyaline-like cartilage that lines the contact surfaces in a particular joint (articular surfaces), ie the articular cartilage is the portion of bone that has not been invaded by ossification. Due to this coating the articular surfaces are smooth, polished and whitish in color. The articular cartilage is avascular and also has no innervation. Therefore, its nutrition, especially in the most central areas, is precarious, which makes the regeneration, in case of injuries, more difficult and slower. The joint capsule is a connective membrane that surrounds the synovial joint like a cuff. It has two layers: the fibrous membrane (external) and the synovial membrane (internal). The former is more resistant and may be reinforced at some points by ligaments designed to increase its resistance. In many synovial joints, however, there are ligaments independent of the joint capsule, and in some, such as the knee, there are also intra-articular ligaments. The articular cavity is the space between the articular surfaces and is filled with synovial fluid.

Ligaments and joint capsules are intended to maintain the union between bones, but in addition, they prevent movement in undesirable planes and limit the range of motion considered normal. The synovial membrane is the innermost layer of the joint capsule. It is abundantly vascularized and innervated and is responsible for the production of synovial fluid (synovium), which is similar in consistency to egg white and has the function of lubricating and nourishing the articular cartilages. Vertebral stability is given by static and dynamic elements of the spine, being the static ones: vertebral bodies, facet joints, joint capsule, invertebral discs and spinal ligaments; and the dynamic ones: the musculoskeletal system and ligaments, especially the multifidus and transverse muscles of the abdomen.

8. Recognize the types of movement allowed by the synovial joints. Synovial joint movements are grouped into 4 main categories: (1) sliding, (2) angular movements, (3) rotation, and (4) special movements, which occur only in certain joints. Slipping Sliding is a simple movement in which practically flat bone surfaces move back and forth and side to side. There is no significant change in the angle between the bones. The range of sliding movements is limited due to the joint capsule structure, associated ligaments and bones, however, these sliding movements can also be combined with rotation. The intercarpal and intertarsal joints are examples of joints where sliding movements occur. Angular movements Angular movements increase or decrease the angle between the bones of the joint. The main angular movements are flexion, extension, lateral flexion, hyperextension, abduction, adduction and circumduction. These movements are always studied with reference to the anatomical position. Flexion, extension, lateral flexion and hyperextension Flexion and extension are opposite movements. In flexion, there is a decrease in the angle between the bones of the joint, and in extension there is an increase in the angle between the bones of the joint, often to return a part of the body to the anatomical position after being flexed. In general, both movements happen on the sagittal plane. Although flexion and extension usually occur in the sagittal plane, there are some exceptions. For example, flexion of the thumb involves medial movement of the thumb, crossing the palm at the carpometacarpal joint between the trapezoid and the metacarpal thumb, as when touching the opposite side of the palm with the thumb. Another example is the movement of the trunk to the right and left sides at the waist. This movement, which occurs in the frontal plane and

involves the intervertebral joints, is called lateral flexion. Continuation of extension beyond the anatomical position is called hyperextension.

Abduction, adduction and circumduction Radial abduction or deviation is the movement of a bone in the opposite direction from the midline, ulnar adduction or deviation is the movement of a bone towards the midline. Both movements usually occur in the frontal plane. O lateral movement of the humerus at the shoulder joint, lateral movement of the palm at the wrist joint, and lateral movement of the femur at the hip joint are examples of abduction. Adduction is the movement back to the anatomical position of each of these body parts. The midline of the body is not used a...