Biomechanics: Joints Movement - Research Paper Example

Biomechanics, joints movement Biomechanics, joints movement Introduction Biomechanics can be defined as the application ofmechanical principles to living structures, specifically to the human body’s locomotor system. Biomechanics, therefore, involves the interrelations of muscles, joints and skeleton. The bones tend to form the levers while the ligaments around the joints form the hinges. The muscles tend to provide forces for moving the levers about the joints. Kinematics is a mechanics’ branch that involves the geometry of objects’ motion that is velocity, displacement and acceleration without considering the forces producing motion (Everett & Kell, 2010). On the other hand, kinetics is the study of the relationship between the force system acting on a body and the change produced in body motion. This implies that human motion employs various aspects for it to take place. Bones which form points play a pivotal role in facilitating human motion as the document analyzes. Discussion Joints are the key factors of human movement. The term joint in human body describes the way bones are coupled to other bones by a muscle, ligaments and tendons. There are several joint types in a human body. They include hip joint and shoulder joint, they are joints formed by a socket and a ball. Other types of joints include the knee or elbow which are formed when the ends of two bones or more come together. Joints consist of muscles, bones, ligaments, cartilage and connective tissues (Dimon & Qualter, 2008). The cartilage prevents the ends of the bones from rubbing each other directly. The cartilage is not as stiff and hard as the bone is, but it is less flexible and stiffer than a muscle. The tendons are the bands of the fibrous tissue which connect the muscles to bones. The ligaments are the fibrous tissue’s bands which connect the bones’ ends together hence forming a joint. Any physiologic movement that is possible at every joint in a body takes place the muscles contract or whenever the gravity acts on the bone hence moving it. This motion can be termed as the osteokinematic movement. This movement describes how every bony joint partner moves in relation to the other partner. The specific movements which take place at the articulating surfaces of joints are termed as the arthrokinematic movement. Osteokinematic movement or the motions between the bones only is not sufficient. This is because there is no concern which is given to the exact matter that takes place at the joint because coupling involves commonly motion coupling around various axes. Arthrokinematic movements also consider the forces which have been applied to the joint and also include the accessory movement which occurs in a particular articulation. It is hence important to relate the osteokinematic movement witharthrokinematic movement whenever joint motion is being evaluated (Everett & Trew, 2005). The joint motion entails the mechanical axis’ movement of the moving bone relation to the joint surface that is stationary. The mechanical axis of the joint can be defined as the line passing through the moving bone that is oriented perpendicular to the stationary joint surface’s center. Whenever one of the joint’s surface moves relative to the other joint sliding, rolling, spinning or combinations take place. This implies that the joints facilitate motion when a certain type of movement takes place in them. Motion in a human body cannot take place when the joint has not moved the way it ought to. Spinning, for instance, refers to the rotational movement around the available mechanical axis. This motion is only possible as real movement in the shoulder, hip and proximal radius (Dimon & Qualter, 2008). Rolling, on the other hand, takes place whenever the surface of a bone contact tends to point at the same interval of the other bone. Slide takes place when it is only one point of the joint surface contacts several different points on the joint surface that is opposing. In most of the human body’s joints, these motions tend to take place simultaneously. The concave-convex rule relates to the expected coupling of translational (slide) and rotational (roll) movements (Everett & Kell, 2010). Whenever a convex surface tends to move on a concave surface, rolling and sliding are expected to take place in different direction. Whenever a concave surface tends to move on a convex surface rolling and sliding takes place in the same direction. Pure roll movement tends to take place in case of a joint dislocation while pure sliding is possible in case of a surface impingement. Moreover, the coupling of slide and roll is crucial anatomically because less articular cartilage is required in a joint so as to facilitate movement and decrease joint wear. These are essential concepts in the clinical decision making regarding the restoration of the restricted joint motion. Spin and roll can be restored using passive range of motion procedures which help in inducing the arthrokinematic movements of that dysfunctional joint (Soames, 2002). When restoring slide movements, the manipulative or thrust techniques are required. These techniques are also applicable in solving the rolling and spinning problems. It is worth noting that when the object is moving, the axis through which the movement is taking place can vary in its placing from one time to another. This can be termed as instantaneous axis of rotation (IAR). It is used in denoting this location point. An asymmetric force that is applied to a joint can cause some shifting in the normal IAR. This concept has great value in that every type of plane motion is describable relative to IAR (Everett & Trew, 2005). The concept plays a pivotal role in describing the plane movement or the movements in two different dimensions. Whenever a three-dimensional motion takes place between objects, a unique axis is formed in space which is referred to as the helical axis of motion (HAM) or the screw axis of motion. HAM tends to be the most precise way of describing motion that is occurring between the irregular shaped objects like anatomic structures. This is because identification of such objects’ reference points accurately and consistently is difficult. Most of the movements tend to take place around and via various axes simultaneously. This implies that in human context, pure movements occur in very rare cases. The extent and nature of a human joint motion is determined specifically by the joint structure and more so the direction and the shape of the joint surfaces (Dimon & Qualter, 2008). There are no two opposing joints’ surfaces which perfectly match. Similarly, they are not geometric perfectly. All human joints have a certain degree of curvature which is never constant but changes from one point to another. As a result of the incongruence that takes place between the joint surfaces a play and joint space is required so as to allow free movement. This joint play tends to be an accessory movement which is crucial for the joint’s normal functioning. The joint’s resting position or its neutral position takes place when the joint capsule is most relaxed and when the greatest play is possible (Soames, 2002). The joint’s motion comprises of five different movement qualities that need to be present for the joint to function normally. These qualities include the active range of motion, joint play, end feel or play, passive range of motion and the paraphysiologic movement. When the joint is in a close-packed neutral position, the joint play is required to be available. A range of active movement which is under the musculature control tends to follow (Tözeren, 2000). The passive motion is range is the other quality. It is usually produced by an examiner and entails the active range coupled with a small degree of movement in an elastic range. The resistance elastic barrier is hence encountered that exhibits the end feel characteristic movement. The small movement that is available and surpasses the elastic barrier occurs post-cavitation and is usually termed as the paraphysiologic movement. The joint movement beyond the paraphysiologic barrier tends to take the joint beyond its anatomic integrity’s limit hence into a movement’s pathologic zone. Once the joint enters the pathologic zone, the joint structures tend to get damaged including the soft tissue and the osseous components. Both the end-feel and joint play movements are believed to be essential for the joints normal movement (Dimon & Qualter, 2008). There are four main movements that take in joints so as to facilitate the intended body motion. It worth noting that the joints are the key determinants of every motion a human being takes. The joint’s motions can be classified in four different kinds namely rotation, circumduction, angular and gliding movements. The gliding movement is one of the movements which take place in bones. It is the simplest type of motion that can occur in a joint. It entails a surface moving or gliding over another without any rotary or angular movement. The movement is very common to all types of movable joints. However, in some especially in the most of the tarsus and carpus articulations, it is the sole motion permitted (Everett & Kell, 2010). The motion is never confined to the plane surfaces but it can exist between any contiguous surfaces of any form. The angular movement is the other movement that takes place in joints. It takes place between the long bones only and through it the angle between the two bones tends to diminish or increase. It may take place backward and forward hence constituting the extension and the flexion (Tözeren, 2000). It can also take place toward and from the body’s median plane or in the case of toes or fingers, from the middle line of the foot or hand thus constituting the abduction and adduction as shown in the figure 1 below. The strict hinge-joints or the ginglymoid tends to admit the extension and flexion only. The combined extension and flexion movements take place in the more movable joints like the shoulder, the hip, thumb’s carpometacarpal joint and the wrist. Figure 1 Circumduction is another form of motion that takes place between the bone’s head and the articular cavity. It takes place when the bone s made to circumscribe a conical shape. The cone’s base tends to be the bone’s distal end, the apex that is in the articular cavity. This type of a motion is usually seen in the hip joints and shoulder. Rotation is the other type of movements in joints (Everett & Kell, 2010). This is the movement in which the bone moves around a fixed central axis without being displaced. The rotation axis may lie on a separate bone. A bone can also rotate around its longitudinal axis such as the rotation at the shoulder-joint as indicated in figure 2 below. Figure 2 The muscles’ ligamentous actions are other crucial action that facilitates movements in the joints. The movements of various joints of a limb are combined by long muscles passing over various joints. When they are relaxed and stretched to a great extent, they act as elastic ligaments when it comes to restraining particular movements of a joint except when they are combined with each other’s corresponding movements (Tözeren, 2000). This implies that the hamstring muscles’ shortness prevents the complete flexion of the hip unless the knee-joint get flexed in order to bring their attachments nearer together. These arrangements are used in three different ways. One of the ways is coordinating the types of movements which are most habitual and necessary. This enables them to be performed with the least power expenditure. The second way is that it helps the short muscles which pass over one joint only to act upon more than a single joint. The third way is providing joints with ligaments which are of great power in movements’ resistance to an extent of incompatible with joint’s mechanism and at the same time yield power when it is necessary (Everett & Trew, 2005). These movements in the body joints facilitate various activities which facilitate the mobility of either the whole body or some parts of the body. It is with the help of joints that people manage to stand, sit, talk, run and walk among other activities. Misleading information In this study, however, there is some information that can be termed as misleading. This is mostly because they seem to counter knowledge about the bones hence creating a kind of confusion. One of the information I found misleading is that joint movement may change depending on the nature of force subjected to it. However, the knowledge about bones indicates that the movements of bones are dictated by the shape formed by the combining bones to form the joint (Tözeren, 2000). This implies that every joint has a unique shape that suits the intended motion. It is hence misleading or confusing to argue that joint’s movement can change by whatever means unless in case of a deformation. Similarly, it has been recorded that joints can be classified broadly as either permanent or temporal. This is very confusing and misleading information. It is hard to understand how joints human joints can be temporal. It is difficult to figure out the factors considered so as to classify a joint as either permanent or temporal (Everett & Trew, 2005). Everything temporal implies that it can be dismantled anytime and life continues normally since it has been fixed to serve just a short term or a minor purpose. This information is therefore quite misleading. Conclusion The discussion above has revealed clearly that joints are integral facilitators of human motion. It is with the help of joints that the whole body as well as the body parts can be able to move and hence accomplish a specific task. Without the joints, therefore, human motion will not be possible. It is worth noting that the human motion comes as a result of the joints’ motion. The joints move so that the body can be able to move. It is, therefore, an integral part of the biomechanical. References Dimon, T., & Qualter, J. (2008). Anatomy of the moving body: A basic course in bones, muscles, and joints. Berkeley, Calif: North Atlantic Books. Everett, T., & Kell, C. (2010). Human movement: An introductory text. Edinburgh: Churchill Livingstone/Elsevier. Everett, T., & Trew, M. (2005). Human movement: An introductory text. Edinburgh: Churchill Livingstone. Soames, R. (2002). Joint motion: Clinical measurement and evaluation. Edinburgh: Churchill Livingstone. Tözeren, A. (2000). Human body dynamics: Classical mechanics and human movement. New York [u.a.: Springer. Read More