JOINTS Arthrology Flexible connective tissue form joints that

JOINTS (Arthrology) • Flexible connective tissue form joints that hold bones together , while still permitting some motion • A joint, also called articulation or arthosis is a point of contact between two bones, a bone and cartilage or bone and teeth • The scientific study of joints is called arthrology. Chaitali prabhudesai

Joint Classification The joints are classified in two different ways: Based on their structure-Structural Classification Based on their function: Functional Classification The structural classification is based on two criteria 1)The presence or absence of a space between articulating bones called synovial cavity 2)The type of connective tissue that binds the bones together • • Chaitali prabhudesai

Joint Classification • Structurally joints are classified as following: – Fibrous joints : the bones are held together by fibrous connective tissue that is rich in collagen fibers. No synovial cavity. – Cartilaginous joints: the bones are held together by cartilage. No synovial cavity. – Synovial joints: the bones forming the joint have a synovial cavity and are united by dense irregular connective tissue. Chaitali prabhudesai

Joint Classification • • Functionally joints are classified as following: Synarthosis: An immovable joint Amphiarthosis: A slightly movable joint Diarthosis: A freely movable joint. All Diarthosis are synovial joints. They have a variety of shapes and permit several different types of movements Chaitali prabhudesai

Fibrous Joints • These are joints that lack a synovial cavity and the articulating bones are held very closely together by fibrous connective tissue. They permit little or no movement. They are further classified in three types: – Sutures – Syndesmoses – Gomphoses Chaitali prabhudesai

Types of Fibrous Joints – Sutures: thin layer of dense connective issue. Unites bones of the skull. – E. g. coronal suture between parietal and frontal bones – The irregular interlocking of sutures give them additional strength and decrease the changes of fracture – Because a suture is immovable, it is functionally classified as a synarthrosis. – Some sutures are replaced by bone in the adult. Such a suture is called synostosis. (or a joint in which there is complete fusion of two separate bones in one bone) Chaitali prabhudesai

Types of Fibrous Joints Chaitali prabhudesai

Types of Fibrous Joints – Syndesmoses: there is a greater distance between the bones and more fibrous connective tissue. The tissue is either arranged as a bundle (ligament) or as a sheet (interosseous membrane). – Example: distal tibiofibular joint where anterior tibiofibular ligament connects the joint also the interosseous membrane between parallel borders of tibia and fibula – Because it permits slight movement, a syndesmosis is classified functionally as an amphiarthrosis. Chaitali prabhudesai

Chaitali prabhudesai

Types of Fibrous Joints • Gomphoses- this is a type of fibrous joint in which a cone-shaped peg fits into a socket. The only example are the articulations of the roots of the teeth with the sockets of the alveolar processes of the maxillae and mandible. The dense fibrous connective tissue is called the periodonatal ligament. This is functionally classified as a synarthrosis. Chaitali prabhudesai

Chaitali prabhudesai

Cartilaginous Joints • This also lacks a synovial cavity and permits little or no movement. • Bones are connected by a hyaline cartilage or fibrocartilage • These are further divided into : – Synchondroses – Symphyses Chaitali prabhudesai

Types of Cartilaginous Joints – Synchondroses: here the connecting material is hyaline cartilage. Example is the joint between the first rib and manubrium of the sternum. Chaitali prabhudesai

Types of Cartilaginous Joints • Symphyses: here the ends of the articulating bones are covered with hyaline cartilage but the bones are connected by a broad flat disc of fibrocartilage. • All symphyses occur in the midline of the body • Examples: pubic symphysis, junction of the manubrium and sternum, intervertebral joints. Functionally, this is an amphiarthrosis, a slightly movable joint. Chaitali prabhudesai

Synovial Joints • The unique characteristic of a synovial joint is presence of a space called synovial cavity between articulating bones • Because the synovial joint allows the joint to be freely movable all synovial joints are classified as diarthoses • The bones of synovial joint are covered by a layer of hyaline cartilage called articular cartilage • The cartilage covers the articulating surface of the bone with a smooth slippery surface but does not bind them together • It also helps to reduce friction between the joint during movement and help to absorb shock Chaitali prabhudesai

Synovial Joints • Articular Capsule: A sleeve like articular capsule surrounds the synovial joint and unites the articulating bones • It is composed of two layers a fibrous capsule usually consist of irregular dense connective tissue that attaches to the periosteum of articulating bone • The flexibility of this capsule permits considerable movements , while its tensile strength helps the bones from dislocation Chaitali prabhudesai

Synovial Joints • The inner layer of this articular capsule is a synovial membrane which is composed of areolar connective tissue and elastic fibers • At many synovial joints the synovial membrane includes accumulations of adipose tissue called articular fat pad e. g. knee joint Chaitali prabhudesai

Synovial Joints • Synovial Fluid: The synovial membrane secretes synovial fluid , a viscous clear or pale yellow fluid • It forms a thin film over the surfaces with articular capsule • Its functions include reducing friction by lubricating the joint, absorbing shock , supplying o 2 and nutrients to and removing co 2 and metabolic waste from chondrocytes within articular cartilage Chaitali prabhudesai

Synovial Joints • Bursae and Tendon Sheaths: The various movements of the body create friction between the moving parts • Saclike structures called bursae are situated to alleviate friction in some joints like knee and shoulder • They are filled with a small amount of fluid like the synovial fluid • Tendon Sheaths also reduce friction at joints, they wrap around certain tendons that produce friction. Chaitali prabhudesai

Synovial Joints Chaitali prabhudesai

Types of Synovial Joints • Planar joints • Hinge Joints • Pivot Joints • Condyloid Joints • Saddle Joints • Ball-and-Socket Joints- Chaitali prabhudesai

Types of Synovial Joints • Planar joints- the articulating surfaces are flat or slightly curved. • Planar joints permit gliding movements • These joints are said to be non axial because the motion they allow does not occur around an axis or around a plane • Example are intercarpal joints, intertarsal joints, sternoclavicular joints, acromioclavicular joints, sternocostal joints, vertebrocostal joints. Chaitali prabhudesai

Chaitali prabhudesai

Types of Synovial Joints • Hinge Joints-the convex surface of one fits into the concave surface of another. • The hinge joint produces an angular opening and closing motion like that of a hinged door • In most joints one bone remains in a fixed position while the other moves around an axis • These as monoaxial as they allow motion around a single axis • Hinge joint permit only flexion and extension • Eg. Knee, elbow, ankle, interphalangeal. Monaxial (uniaxial). Chaitali prabhudesai

Trochlea humerus Trochlear notch ulna Chaitali prabhudesai

Types of Synovial Joints • Pivot Joints-here the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament. • This is monaxial , as it allows rotation only around its own longitudinal axis • Examples atlanto-axial joint, radioulnar joint : turns palm anteriorly and posteriorly. Chaitali prabhudesai

Angular ligament Head Of radius Radius ulna Chaitali prabhudesai

Types of Synovial Joints • Condyloid Joints-also called ellipsoidal joint. The convex ovalshaped projection of one fits into the oval-shaped depression of another. • A condyloid joint is a biaxial joint because it permits movements around two axis • It allows flexion, Extension, Adduction, Abduction and circumduction • Eg. Wrist and metacarpophalangeal joints. Biaxial. Chaitali prabhudesai

Chaitali prabhudesai

Types of Synovial Joints • Saddle Joints-here the articular surface of one bone is saddle-shaped and the articular surface of the other fits into the “saddle”. • Saddle joint is biaxial joint because it permits movements around two axis • It allows flexion, Extension, Adduction, Abduction and circumduction • Eg. Carpometacarpal joint. Biaxial. Chaitali prabhudesai

Chaitali prabhudesai

Types of Synovial Joints • Ball-and-Socket Joints- this consists of the ball -like surface of one bone fitting into a cuplike depression of another bone. • These joints are multiaxial as they permit movement about three axis • It allows flexion, Extension, Adduction, Abduction and circumduction and rotation • Egs. Shoulder and hip joints. Chaitali prabhudesai

Glenoid Cavity of Scapula Chaitali prabhudesai

Types of Movements • Gliding: This is a simple movement in which relatively flat bone surfaces move side-to-side and back-and-forth with respect to one another • There is no significant alteration of angle between the bones • E. g. Intercarpal and Intertarsal joint • Angular movements: Four angular movements may occur in various diarthrodial joints: flexion, extension, abduction, and adduction (F 7. 8). Angular movements increase

Types of Movements • FLEXION When a bone is moved in an anteriorposterior plane in such a manner as to decrease the angle between it and its adjoining bone, flexion occurs. Examples include bending the elbow, bringing the thigh towards the abdomen, and bringing the calf of the leg toward the back of the thigh. Pulling the heel upward, thus lowering the toe region of a foot, is referred to as plantar flexion. Chaitali prabhudesai

Types of Movements EXTENSION Extension is the opposite of flexion. It causes the angle between adjoining bones to increase. Extension occurs when a flexed joint is moved back to the anatomical position, such as straightening the arm, thigh, and knee. Hyperextension occurs when the part is moved beyond the straight position, such as arching the back or bringing the limbs posteriorly beyond the plane of the body. Raising the toe region toward the shin is often considered to be extension of the foot, but is called dorsiflexion. Chaitali prabhudesai

Types of Movements • ABDUCTION When a part, such as a limb, is moved away from the midline of the body, abduction occurs. In the case of the fingers and toes, abduction involves moving them away from the midline of the hand or foot. • ADDUCTION Adduction, the reverse of abduction, involves the movement of a part toward the midline of the body, back toward the anatomical position. In the case of the fingers and toes, the movement is toward the Chaitali prabhudesai

Types of Movements • Circular Movements • In addition to the four angular movements, four circular movements are allowed by some diarthrodial joints: circumduction, rotation, supination, and F 7. 8 pronation (F 7. 8) Chaitali prabhudesai

Types of Movements • CIRCUMDUCTION : The joint motion known as circumduction delineates a cone. The base of the cone is outlined by the movement of the distal end of the bone, with the apex of the cone Iying in the articular cavity. The movement is actually a sequential combination of flexion, abduction, extension, and adduction. Circumduction is common at the hip and the shoulder joints, and is possible in other joints also. • ROTATION The motion of a bone around a central axis is rotation. If the anterior surface of a bone such as the humerus or femur moves inward, it is called inward (medial) rotation. When the anterior surface turns outward it is outward (lateral) rotation.