Mod 5 - Lecture 2 - Articulations PDF

Articulations Classification of joints and structure of some important joints in body  Learning Objectives Compare and contrast the two ways to classify joints. Describe the structure and types of the synovial joints Describe the structure and function of the joints that make up the shoulde...

Articulations Classification of joints and structure of some important joints in body  Learning Objectives Compare and contrast the two ways to classify joints. Describe the structure and types of the synovial joints Describe the structure and function of the joints that make up the shoulder complex. Describe the structures of the elbow and radio-ulnar joints. Describe the structure and function of the hip joint. Analyze the structure and function of the knee joint. Joints (Articulations) Joints (articulations) are unions or junctions between two or more bones or rigid parts of the skeleton. Greek root arthro means joint. Joints can be classified by function or structure Functional classification is based on amount of movement Synarthroses—immovable; common in axial skeleton Amphiarthroses—slightly movable; common in axial skeleton Diarthroses—freely movable; common in appendicular skeleton (all synovial) Structural classification is based on material that binds bones together: Fibrous—Bones are connected by fibrous connective tissue Cartilaginous—Bones are connected by cartilage Synovial—Bones are connected by synovial membrane  Fibrous Joints 3 types of fibrous joints: 1. Sutures – Short fibers between bones. Not movable (Synarthroses) Examples: sutures in skull. 2. Syndesmosis – Long fibers between bones. Slightly movable (Amphiarthroses) Examples: between radius and ulna or tibia and fibula. 3. Gomphosis – Periodontal ligament between bones: Not movable (Synarthroses) Examples: Teeth roots in jaws.  Cartilaginous Joints 2 types of cartilaginous joints: Synchondroses – Hyalin cartage between bones. Not movable (Synarthroses) Examples: costochondral joints, epiphyseal plates in long bones. Symphyses – Fibrocartilage between bones. Slightly movable (Amphiarthroses) Examples: Intervertebral discs, symphyses pubis. Summary of Joint Classes  Classification of Joints Structural classification Functional classification Fibrous Synarthroses 1. Sutures 2. Gomphosis 3. Syndesmosis Cartilaginous 1. Synchondrosis Amphiarthroses 2. Symphysis Synovial Diarthroses Synovial Joints Most movable type of joint, all are diarthroses Each contains these components: a fluid-filled joint cavity Articular cartilage Articular capsule has 2 layers: Fibrous layer—outer layer of dense irregular connective tissue Synovial membrane—inner layer ofloose connective tissue Synovial fluid Reinforcing ligaments Some synovial joints contain an articular disc Classification based on the shape which determines types of movements Movements Allowed by Synovial Joints Three basic types of movement Gliding—one bone glides across the surface of another, no change in the angles between joints. Angular movement—movements change the angle between bones, can be uniaxial, biaxial, or multiaxial Flexion and extension (bending and straightening) Abduction and adduction (moving closer or farther away from the trunk) Circumduction (combination of two that looks like making a cone in space) Rotation—movement around a bone’s long axis Synovial Joints Classified by Shape Plane joint - Articular surfaces are flat planes Types of movements: gliding Ex: Intercarpal, intertarsal, Acromioclavicular Hinge joints – Uniaxial, allows angular movement in one plane. Types of movements: Flexion/extension Ex: Elbow, Knee, Ankle, Interphalangeal Pivot joints – Uniaxial allows only rotation of bones around their long axis Types of movements: rotation Ex: Atlantoaxial, radioulnar.  Synovial Joints Classified by Shape Condylar (or ellipsoid) joints – Biaxial allows angular movements in two planes: Types of movements: abduction/adduction, flexion/extension, circumduction Ex: Radiocarpal, Metacarpophalangeal Saddle joints – Biaxial allows angular movements in two planes: Types of movements: abduction/adduction, flexion/extension, circumduction, opposition Ex: - Thumb (1st carpophalengeal) Synovial Joints Classified by Shape Ball-and-socket joints – multiaxial—allow movement in all axes, Spherical head of one bone fits into round socket of another Types of movements: abduction/adduction, flexion/extension, rotation, circumduction, Ex: Shoulder and hip joints Selected Synovial Joints Shoulder (glenohumeral) joint The most freely movable joint lacks stability Articular capsule is thin and loose Muscle tendons contribute to joint stability Important ligaments: Glenohumeral ligament Coracohumeral ligament Coracoacromial ligament  Bursa and Tendon Sheaths Bursa Membrane bound pocket filled with synovial fluid Found where tendons or ligaments rub against bone or other tissue Reduces friction, shock absorption Tendon Sheath A bursa that extends along a tendon for some distance  Selected Synovial Joints Elbow joint The hinge joint – Articulation of the humero-ulnar joint with the trochlear notch of the ulna allows only flexion and extension The Radio-ulnar Joints – proximal and distal allow the rotational movements of supination and pronation Important ligaments: Ulnar collateral ligament Radial collateral ligament Annular ligament The Elbow Joint  Selected Synovial Joints Hip joint A ball-and-socket structure Movements occur in all axes Limited by ligaments and acetabulum Head of femur articulates with acetabulum Stability comes chiefly from acetabulum and capsular ligaments: Iliofemoral Pubofemoral Ischiofemoral Ligament of the head of femor  Selected Synovial Joints Knee joint (tibiofemoral joint) Acts primarily as a hinge joint Two fibrocartilage menisci occur within the joint cavity Femoropatellar joint—shares the joint cavity, allows patella to glide across the distal femur Knee Joint Ligaments of the knee joint Extracapsular: Fibular and tibial collateral ligament Intracapsular ligaments Cruciate ligaments (cross each other like an “X”) Anterior cruciate ligament — prevents anterior sliding of the tibia Posterior cruciate ligament — prevents forward sliding of the femur or backward displacement of the tibia Any Questions?