Stedmans Concise Dictionary defines a joint as follows: joint in anatomy, the place of attachment, generally more or less mobile, between two or more bones ... and is classified into three general morphological types: fibrous joints, cartilage joints and synovial joints . (eleven). In this edition, the following definition adheres to the above-mentioned meaning with the addition of the joint name: The joint is defined as a skeletal, bone-to-bone connection held together by fibrous, cartilage, or synovial tissue. Joints are named after the bones that are held together. In some joints, the bones are held so close together that there is no noticeable movement. They provide great stability. Some joints provide stability in one direction and freedom of movement in the opposite direction, while others offer freedom of movement in all directions. The joints that provide little or no movement are the ones that hold the two sides of the body together. The sagittal suture of the skull is considered a motionless joint, held together by a strong fibrous membrane. The sacroiliac joint and the pubic symphysis are considered slightly mobile and held together by strong fibrocartilage membranes. Most joints fall into the category of joints that move freely and are held together by the synovial membranes. The elbow and knee joints are essentially jointed joints. The structure of the articular surfaces and the strong lateral and medial ligaments limit lateral movement, while the posterior ligaments and muscles limit extension. Therefore, there is stability and strength in the extended position. Conversely, the shoulder joints can move in all directions and have less stability. 


The overall structure of the muscle helps determine muscle action and affects how a muscle responds to stretching. Muscle fibers are arranged in bundles called bundles. The arrangement of the fascicles and their attachments to the tendons varies anatomically. In the general structure there are two main divisions: fusiform (or spindle) and pennada. A third, fan-like arrangement is probably a modification of the other two, but has a different clinical significance. In the spindle-shaped structure, the fibers are arranged essentially parallel to the line from the origin to the attachments, and the fascicles terminate at both ends of the muscle in flat tendons.In the pinnate structure, the fibers insert obliquely into the tendon or tendons that run along the muscle to one side (i.e., unipennate) or across the belly of the muscle (i.e., bipennate). In all likelihood, the long fusiform muscle is the most vulnerable to stretching. The movement of the joint is in the same direction as the length of the fiber and each longitudinal component depends on the others. The pinnate muscles are probably the least vulnerable to stretching, because the muscle fiber is oblique to the direction of joint movement and because the fibers and bundles are short and parallel and therefore do not depend on other segments for the continuity of joint action. The fan-shaped muscle has the advantages and disadvantages of the previous two. It could be thought of as a group of muscles arranged next to each other to form a fan-shaped unit. Each segment is independent in the sense that it has its own origin with a common entry. For example, in the fan-shaped pectoralis major, the clavicular part may not be affected but the sternal part may be paralyzed in a spinal cord injury. According to Grays Anatomy, the "arrangement of fascicles is related to the power of the muscles". Those with relatively few fascicles, which run the full length of the muscle, have greater range of motion but not as much power. The peniform muscles, with a large number of bundles distributed along the tendons, have greater power but less freedom of movement "

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