Human Anatomy and Physiology Joints

Joints Topics • Discuss both functional and structural classifications for body joints • Describe the characteristic features for fibrous, cartilaginous, and synovial joints and give examples of each • Define and identify the different body movements • Discuss the structure of specific body joints and the movements allowed by each • Explain the development of body joints Bones come together in places in the body called joints, which enable us to move our bodies in different ways. a key : • Joints are the sites in the body where bones meet. They enable movement and classify either its structure or its function. • Structural classifications of joints include fibrous, cartilaginous, and synovial joints. • Functional classifications of joints include immovable, slightly movable, and freely movable joints. Movable (synovial) joints are more abundant and include six types: axial joints, hinges, caudal (condylar), saddle (saddle) joints, flat joints, and ball joints (acetabular). There are three types of joints in the body. Synovial joints are freely movable and allow movement at the site where the bones meet. They provide a wide range of motion and flexibility. Other joints provide greater stability and less flexibility. Bones in cartilaginous joints are attached to cartilage and are slightly mobile. Bones in fibrous joints are immovable and are connected by fibrous connective tissues. Joints can be classified according to their structure or function. Skeletal classifications are based on how the bones are attached to the joints. Fibrous, synovial, and cartilage fibers are structural classifications of joints. Classifications based on joint function consider how mobile bones are in joint locations. These classifications include immovable joints (a fibrous joint), slightly movable joints (aductive joint), and freely movable joints (rotary joint). Immovable (fibrous) joints Fibrous joints hold the bones of the skull together to protect the brain. Fixed or fibrous joints are those that do not allow movement (or allow very little movement) at joint sites. The bones in these joints do not have a common cavity and are held together structurally by thick, fibrous connective tissue, usually collagen. These joints are important for stability and protection. There are three types of immovable joints: the suture joint, the fibrous joint, and the immobile sphenoid joint. • Sutures: These narrow fibrous joints connect the bones of the skull (except for the jawbone). In adults, the bones are held tightly together to protect the brain and help shape the face. In newborns and infants, the bones in these joints are separated by a larger area of connective tissue and are more flexible. Over time, the bones of the skull fuse together to provide more stability and protection for the brain. • Syndesmosis: This type of fibrous joint connects two bones that are relatively far apart. Bones are connected by tissue ligaments or the thickened membrane (the membrane between bones). The fibrous joint that connects the bones of the forearm (between the elbow and the wrist) and the two long bones of the lower leg. Gomphosis: This type of fibrous joint holds the tooth in place in its cavity in the upper and lower jaw. Gomphosis is an exception to the rule that connects joints to bone, because it connects teeth to bone. This specialized joint is also called a socket and socket joint and allows limited movement. Slightly movable joints (cartilaginous) The intervertebral discs are cartilaginous joints, made up of a thick fibrous membrane, that support the bones while allowing limited movement. Slightly movable joints allow some movement but provide less stability than immovable joints. These joints can be structurally classified as cartilaginous joints, as the bones are attached to the cartilage in the joints. Cartilage is a strong, flexible connective tissue that helps reduce friction between bones. Two types of cartilage can be found in cartilaginous joints: hyaline cartilage and fibrocartilage. Hyaline cartilage is very flexible and elastic, while fibrocartilage is stronger and less flexible. Cartilaginous joints, which consist of hyaline cartilage, can be found between certain bones in the rib cage. The intervertebral discs located between the spinal vertebrae are examples of slightly movable joints made up of fibrocartilage. The fibrous membrane provides support to the bones while allowing limited movement. These are important functions as they relate to the spine as the spinal vertebrae help protect the spinal cord. The pubic symphysis (which connects the left and right hip bones) is another example of a cartilaginous joint that unites the bones with fibrocartilage. The pubic symphysis helps support and stabilize the pelvis. Freely movable joints (synovials) Synovial joints are freely movable and provide the greatest degree of mobility Freely movable joints are structurally classified as synovial joints. Unlike fibrous and cartilaginous joints, synovial joints contain a joint cavity (fluidfilled space) between the connecting bones. Synovial joints allow more movement but are less stable than fibrous and cartilaginous joints. Examples of synovial joints include the joints in the wrist, elbow, knees, shoulders, and hip. Three major structural components are present in all synovial joints and include the synovial cavity, articular capsule, and articular cartilage. • Synovial cavity: This space between adjacent bones is filled with synovial fluid where the bones can move freely with respect to each other. The synovial fluid helps prevent friction between the bones. • Articular capsule: It consists of fibrous connective tissue, this capsule surrounds the joint and connects to the adjacent bones. The inner layer of the capsule is lined with a synovial membrane that produces thick synovial fluid. • Articular cartilage: Inside the articular capsule, the rounded ends of the adjacent bones are covered with smooth articular cartilage (relating to the joints) consisting of hyaline cartilage. Articular cartilage absorbs shock and provides a smooth surface for fluent movements. In addition, bones in synovial joints may be supported by structures outside the joint such as ligaments, tendons, and bursae (fluid-filled sacs that reduce friction between the supporting structures at joints). Types of synovial joints in the body Synovial joints allow a number of different types of body movements. Six types of synovial joints are located in different locations in the body. • Pivot joint: This joint allows rotational movement around one axis. One bone encircles a ring formed by the other bone in the joint and ligaments. The bone that goes around the ring may rotate or it may rotate around the bone. The joint between the first and second cervical vertebrae near the base of the skull is an example of an axial joint. The head is allowed to rotate from side to side. • Hinge joint: This joint allows bending and straightening movements along one plane. Similar to door hinges, movement is limited to one direction. Examples of articular joints include the elbow, knee, ankle, and interdigital joints. • Condylar joint: Many different types of movements are allowed by this type of joint, including bending and straightening, from side to side, and circular movements. One bone has an oval, or convex, shape, matching the low oval or concave shape of another bone. This type of joint can be found between the forearm bones and the wrist bones. • Saddle joint: These distinct joints are highly flexible, allowing for bending and straightening, side to side, and circular motions. The bones in these joints form what looks like a rider on a saddle. One bone is turned inward on one side, and the other is rotated outward. An example of a saddle joint is the thumb joint between the thumb and the palm of the hand. • Plane joint: Bones of this type slide past each other in a sliding motion. Bones at planar joints are similar in size and the surfaces where the bones meet at the joint are nearly flat. These joints can be found between the bones of the wrist and the foot, as well as between the collar bone and the shoulder. • Ball joint (acetabular): These joints allow the greatest degree of movement allowing bending and narrowing, from side to side, circular, and rotational motion. The end of one bone in this type of joint is rounded (ball) and fits into the end (socket) of another bone. The hip and shoulder joints are examples of a ball joint (acetabular). Each type of synovial joint allows for specialized movements that allow different degrees of movement. It may allow movement in only one direction or movement at multiple levels, depending on the type of joint. Thus, the joint's range of motion is limited by the type of joint and its supporting muscles. The movement of the body in general depends on the joints, as they facilitate the movement of the bones in different directions, and their function is centered around connecting the bones smoothly. The joints of the human body in the following lines. What are the joints of the human body? What is their importance? And how many? The human race belongs to the family of vertebrates, and they are the organisms that are based on the axis of the fulcrum, which is the spine, and the joints represent that part between each bone and the other, and the number of these joints is 360 joints. They give the person the strength and resistance required to do hard work, and these joints can be damaged if you put too much pressure on them. Therefore, doctors advise slowly increasing the pressure on the joints and bones, and using healthy methods in carrying and lifting heavy objects. We know the following types of joints: Types of joints in the human body Joints are classified according to two types of classifications, structural classifications, which depend on the general shape of the joints, and functional classifications, which define the functions of each type of joint: Classification of the joints of the human skeletal body Cartilage, or what is known as cartilaginous joints, which is located in the form of cartilage between the bones, and works to achieve softness and ease of movement. Synovial joints are characterized by the formation of a synovial layer surrounding the joint; To ensure that it does not rub or stick to the bones or to each other. Fibrous joints, which are connected to the bones by fibrous tissue, keeps the bones together, such as those in the skull. Functional classification of the joints of the human body Fixed joints: They are fixed joints that do not change in shape, and as a person ages, these joints fuse with each other to form one part, such as: the human skull, which at the beginning of life consists of several moving joints, in order to expand and accommodate the increasing growth in childhood age. Low-moving joints or cartilage: These joints help the body to perform light movements in a certain direction, such as the joints of the vertebrae, and this thin layer of joints erodes in some cases, especially with age, causing pain such as back and knee pain. Mobile joints: They are the most joints capable of moving in multiple directions and they are widespread in the human body, such as the thighs and shoulder joints. Thanks to these joints, you can move your arm and leg in various directions and completely freely. Types of joints by shape Let's get acquainted with the three types of joints according to their shape: 1. Fibrous Joints It is one of the fixed joints that can be called the immovable joint, and its place is located between the inflexible bones. In this type of joint, the bones are fused with each other in a way that makes them fixed in place to form a strong bone structure. Examples of these joints are the following: The skull, which consists of a number of bones fused together. the upper jaw. Rib cage. Backbones. Pelvic bones. There are also two types of fibrous joint, namely: Suture: It consists of a fibrous cover. Gomphosis: This is a movable fibrous sphenoid joint. 2. Cartilaginous Joints It is a type of partially movable joint, which includes cartilaginous fusion of joints, and is found in places where fusion occurs between bones through cartilage. A cartilaginous fusion is a temporary cartilaginous joint that is found in young children until the end of puberty. 3. Synovial Joints It is the most common type of joint in the body because it helps the body to move widely, and this type gets its blood and nerve supplies through the existing arteries. This joint helps to complete the following activities: Walking. jogging; Writing. It is one of the joints that have kinetic properties, such as: Flexibility and move easily. Slide over each other. Rotation. The synovial joint is located in the following places: the shoulder. the neck. knee. the wrist. Types of joints by function Functional classification of joints is as follows: joint type. The degree of movement of the joint. Now let's get acquainted with the six types of joints: 1. Ball And Socket Joint In this type, one bone is attached in a hollow space to one of the other bones, and the ball joint helps with the following things: rotational motion. Forward and backward movement. lateral movement. This type is found in the following places: shoulders. thighs; 2. Pivot joint This type helps in several things, which include the following: The ability of bones to turn. Assist in lateral and backward movement as in the neck. Turn around in a limited way only. 3. Hinge joint This joint allows the following movements: Home and Away. bending; Movement calendar. It is also found in various places, here are the most prominent: ankle. elbows. knee. elbows; fingers of the hand. toes. 4. Saddle joint It is a biaxial joint that allows movement on two levels: Flexion and stretching. Dimensions and approximation. The thumb bone is the only one that contains the saddle joint. 5. Condyloid joint It is also a pivot hinge that allows movement from top to bottom, and from one side to the other. They are located in places such as: the wrist. elbow. 6. Gliding joint It is a common type of synovial joint that allows two or more flat or circular bones to move freely together without any friction or fragmentation of the bones. Types of joints according to movement There is another classification of joints according to their ability to move according to the following: Immobile joints: where two or more bones stick together, but without any movement. It is located in the skull bone. Partially movable joints: where two or more bones are fixed together in a tight way that allows them to move only with a limited extent, such as: the vertebrae of the spine. Mobile joints: which include most types of joints in the human body that allow him to move freely. What are the types of joints? Before we get to know the types of joints, we should know the definition of the skeletal system and its most important functions, which are: skeletal system; It is a support and movement system made up of bones, ligaments (ligaments), tendons, muscles and cartilage. Functions: Providing movement with the help of muscles and joints. Giving the body its general shape. Protection and support of internal organs. Production of blood cells (red and white blood cells). Provide a gripping surface for the muscles. Two structures are required for the bones that make up the skeleton to hold together; joints and ligaments. There are 206 bones in our body and 360 joints that connect them. Joints can be called "bone joints". Types of joints: The joints in our body are divided into 3 groups: Fixed or immobile joints (joints of the skull). Semi-motile joints (vertebrae and jawbone). Mobile joints (synovial joints) (joints of the shoulder, arm and leg). First: fixed joints These joints are found where the bones are clamped and tightly connected to each other, as in the skull. Bones connected by immobile joints such as bones welded to each other, some fixed joints are permanent and some are temporary, in the temporary joint the articular bones necessarily fuse sooner or later after birth. For example, all the joints of the skull are temporary except for the joints between the mandible and the middle ear. Second: semi-mobile joints In semi-motile joints, there are cushions (discs) made of elastic cartilage tissue between the two articular bones. Movements of semi-motile joints are limited, bones can move in proportion to the flexibility of the structure between them. As for the elderly, the possibilities of movement decrease due to the loss of elasticity of the ligaments that connect the joints. The joints between the vertebrae that make up the spine can be given as examples of semi-motile joints. Third: movable joints Most of the joints of the body are mobile joints, the space inside each of them is filled with a type of fluid that lubricates the joint during movement. The joint is held together by soft bands called ligaments, which ensure that the bones do not separate during movement. The joint is the point of contact between two bones. The joints and structures around it allow the knee to bend while walking, bend the elbow when lifting something, bend the hip to one side during body movements, hold the body in the hand, and move the head in all directions. There is a slippery fluid between the bones that prevents them from rubbing against each other, this can cause various joint diseases. Movable joints allow some movement, but at the same time provide stability to immovable joints, and can be classified structurally as cartilaginous joints, because they connect cartilage and joints. Cartilaginous joints can be found in the rib cage, and the vertebrae between the spinal vertebrae are movable joints. In order to prevent the deterioration of the joint structure, the muscles, ligaments and bones must be protected from external influences and their structures strengthened. Read also Oils for treating arthritis Synovial fluid properties It is a clear, pale yellow, dark liquid that has the following characteristics: Lubricates the joint surface. Helps reduce friction. Nourishes articular cartilage. It is a rich liquid that contains hyaluronic acid which is the basis of dark and lubricating, and several mucous proteins. Types of synovial joints in the body There are the following types of joints in the body: Flat joints, generally these joints allow one bone to move by sliding over the other, an example is the acromioclavicular joint located above the shoulders. Sealing joints allow bending and expansion in one plane. An example is the elbows. Axial joints provide movement around the axis, meaning that they regulate their rotational movements. An example is the distal radio joint. Compound or bicondylar joints. These joints provide movement from one axis to another with limited rotation. They consist of two convex condyles. An example of this type of joint is the knee joint. The condylar joints provide movement between two perpendicular axes and passive or secondary movement in a third axis. Thus, it allows bending, pulling, pulling and zooming (conical motion). This is how the wrist joint is. Saddle joints, they provide the same range of motion as the condylar joints, but give a greater range of motion, allowing for bending, pulling, pulling and magnification (conical motion) movements. Ball joints allow movement except for sliding. They provide flexion, extension, pulling, rotation and extension (a conical movement). The hip is an example of this type of joint. Synovial joint characteristics Primarily, joints contain a layer of cartilage that covers the articular surfaces of elements such as the skeleton. In this way, the bones are not in direct contact with each other, when these joints are viewed on an X-ray machine, a large space is observed between the adjacent bones. Also, the second characteristic of synovial joints is the presence of an articular capsule. This capsule consists mainly of the inner synovial membrane and the outer fibrous membrane. Synovial membrane: This membrane covers the inner surfaces of the capsules and tendon sheaths of the synovial joints, generally in contact with the fibrous membrane and lubricant of the synovial fluid. This synovial membrane is highly vascular and produces synovial fluid, which then accumulates in the joint space and lubricates the joint surfaces. In addition, closed synovial cysts appear outside the joints, here they form bursae, or tendon sheaths. Bags usually form between tendons and structures such as joints, tendons, bones or skin, which reduce friction when one structure moves against another. Additionally, tendon sheaths surround the tendons and reduce friction. fibrous membrane: The fibrous membrane consists of a dense, irregular connective tissue that, in general, can be said to surround and stabilize the joint. Parts of the fibrous membrane may thicken to form connective tissue that subsequently stabilizes the joint. Connective tissues outside the capsule usually provide additional support. Read also Ankle sprain complications and treatment Other characteristic structures of the synovial joints: Another distinguishing feature of synovial joints is the presence of additional structures within the area covered by the synovium. Some of these additional structures are: Articulated discs: Usually composed of cartilage, including fibrous tissue, it absorbs compressive forces, adapts to changes in the joint surface during movement, and increases the range of motion in the joints. Articulated fat pads: They are usually located between the synovial membrane and the capsule, in addition, they enter and exit these areas as the contour of the joint changes during movement. The synovial joints are surrounded by a synovial capsule that covers the synovial space and connects the bones of the joints, the synovial joint provides the connection between the two bones, and it consists of a cavity lined with cartilage filled with fluid. 4. Movements of body parts and tissues 4.1. body parts movements Preparing to study and define the movements of parts of the body or the body as a whole requires starting to define some concepts, including: A- Gravitational line: It is an imaginary line perpendicular to the surface of the Earth that goes down from the center of gravity of the body, and its determination depends on the location of the center of gravity of the body. b- Anatomical position: It is the position that is based on to determine the basic surfaces and axes as well as movements, which are as follows: Upright standing position. Looking forward (horizontal). The arms are outstretched to the side of the body and the palms are facing forward. Legs clenched and extended, toes pointing forward. C- Surfaces of spatial movement: The surface is defined from a geometrical point of view as the regular spatial plane, and the movement in the vacuum is determined by three perpendicular surfaces or spatial planes that meet at a point that is the center of gravity of the body. These surfaces are: Surface or sagittal plane: it passes through the body vertically to divide it into equal and symmetric halves, right and left, and accordingly it passes through the body from front to back or back. Lateral surface or plane (front vertical): it passes through the body vertically to divide it into front and back halves, and accordingly it passes through the body from one side to the other. Surface or horizontal (transverse) plane: it passes through the body vertically to divide it into upper and lower halves, and accordingly it passes through the body in a plane parallel to the surface of the earth. These three surfaces are called the original spatial planes or planes of motion in a vacuum because they pass through the center of the body's gravity and this means that they divide the body into halves. - It should be noted that when describing the movements of the body or part of its parts, the surfaces used may not be the original surfaces, but it is important for us to understand that any movement of the body or any movement of a part of its parts is attributed to these surfaces or their equivalent in space. D- Axes: The three surfaces are perpendicular to their confluence with each other, and the perpendicularity of each of these surfaces creates an imaginary line known as the axis. This axis is either a point or a clear fixed line around which movement occurs. Among the axes, we mention the following: The sagittal axis: It is the axis that passes through the center of gravity of the body from the back towards the front or vice versa. This axis is formed after the horizontal plane is perpendicular to the sagittal plane so that it rests perpendicular to the front vertical plane. Transverse axis: It is the axis that passes through the center of gravity of the body from one side to the other, and this axis is formed as a result of the perpendicularity of the horizontal plane with the front vertical plane, where this axis is perpendicular to the sagittal plane. Longitudinal axis: It also passes through the center of gravity of the body from the bottom up or vice versa, and this axis is formed after the perpendicularity of the sagittal plane with the front vertical plane, and this axis is perpendicular to the horizontal plane. Note: Those are some notes and collections that helped me through my studies. I share it to help my fellow students in their learning process. I wish you all the best and success. Souad A.N.