1.7 Types of Joints PDF

[00:00:00] >> Types of joints This is the objective for this lecture. Joints are where two or more bones attach, joints can be divided into two categories, synarthrosis and diarthrosis. A synarthrosis joint is a non- synovial joint or joint without a joint cavity. A diarthrosis joint is a synovial j...

[00:00:00] >> Types of joints This is the objective for this lecture. Joints are where two or more bones attach, joints can be divided into two categories, synarthrosis and diarthrosis. A synarthrosis joint is a non- synovial joint or joint without a joint cavity. A diarthrosis joint is a synovial joint or a joint with a joint cavity. [00:00:30] Diarthrosis joints are referred to as synovial joints. Examples include but are not limited to the hip, knee, shoulder and elbow joints. There are five distinguishing characteristics of this type of joint. The joint cavity is enclosed by a fiber elastic joint capsule. The hyaline cartilage covers the surfaces of both of the enclosed bones as you can see in this picture. [00:00:57] The synovial fluid Forms a film over the joint surfaces. The synovial membrane lines the inner surface of the joint capsule. The joint capsule is comprised of two layers, so you can see this fibrous membrane is the outer surface. Synovial joints have a lubricating system called synovial fluid. Synovial fluid allows almost frictionless movement at the joint surfaces. [00:01:31] The composition of synovial fluid is nearly the same as blood plasma with a decreased total protein content and a higher concentration of hyaluronan. Synovial joints are further classified based on their complexity. Simple or uniaxial joints are a single pair of articular surfaces, with one being convex and one being concave. [00:01:55] Examples include hinge joints or trochoid joints. Compound or biaxial joints are a single joint capsule that contains more than a single pair of articulating surfaces. Examples of biaxial joints include condyloid and saddle joints. Complex or triaxial or multiaxial joints contain an inter-articular substance within the joints, such as a meniscus or a disc that increases the number of joint surfaces. [00:02:23] The two types of joints in this category are plain joints and ball and socket joints. Synovial joints can be classified according to their structure or similarity into the following categories. A spheroid or a ball and socket joint is one where the sphere on the head of one bone fits into the rounded cavity on another bone. [00:02:42] This joint allows motions in all three planes. Examples include the heads of the femur and the humerus at the hip and the shoulder. A ginglymoid joint or a hinge joint is characterized by a spool-like surface and a concave surface. An example of a hinge joint is a humeral ulna joint at the elbow. [00:03:02] A saddle or a sellar joint is characterized by a convex surface in one plane and a concave surface in the plane perpendicular to it. Examples of a saddle joint include the carpometacarpal joint of the thumb. And the ellipsoid joint is similar to sphere a joint and that they allow the same types of movement, but to a lesser degree. [00:03:24] Examples of this type of joint are the radiocarpal articulation at the wrist. Continuing with the synovial joint classifications, a pivot joint or a trochoid joint, is characterized by a swivel-like process turning within a ring or a ring on a fulcrum. The ring being formed partly a bone and partly by ligament. [00:03:44] These joints permit only rotations. Examples of pivot joints include the humeral radial joint at the elbow. A planar or a gliding joint is characterized by flat surfaces that slide over each other. Movement at this joint does not occur about an axis and is termed non-axial. Examples of planar joints include the inner metatarsal joints and some inner carpal joints. [00:04:09] And then condyloid joints is characterized by an avoid articular surface or condyle. One bone may articulate with another by one surface or by two but never more than two, if two distinct surfaces are present the joint is called condylar or bicondylar. The cavity is designed in a manner to permit the motions of flexion, extension, adduction, abduction and circumduction but no axial rotation. [00:04:39] These are the references.