Chapter 9: Joints

(Joints) Chapter 9 Articulations: joints where bones meet · Joints hold bones together but permit movement · Point of contact ↳ between two bones ↳ between cartilage and bone ↳ between teeth and bone Classification by Structure · based on the anatomy of the joint · includes: -fibrous joints -cartilaginous joints -bony joints -synovial joints · (bony joints form when fibrous/ cartilaginous joints ossify) Classification by Function · based on the movement of the joint (range of motion) ① synarthrosis ↳ immovable joint ↳ suture or gomphosis ② amphiarthrosis ↳ slightly movable joint ↳ symphysis ③ diarthrosis ↳ Freely moveable joint ↳ synovial joint Fibrous Joints Cartilaginous Joints fibrous connective tissue fibrocartilage or hyaline cartilage · bones held closely together by · little or no movement · eg. cranial sutures · bones tightly connected by · allows little or no movement · eg. Symphysis pubis or sternal angle Synovial Joints · synovial Fluid: produced by the synovial membrane that lines the joint cavity (areolar tissue) · production of synovial fluid is stimulated by joint movement · functions: Accessory Structures: ↳ provides lubrication · cartilage and fat pads ↳ plays a role in shock absorption · tendons ↳ supplies oxygen and nutrients to chondrocytes · ligaments · bursae Articular Motion · linear/gliding movements · angular movements ↳ flexion and extension ↳ abduction and adduction · circumduction · rotation Range of motion: how far a joint can move Movements at Synovial Joints (review textbook pages 271-275) Angular Movements: · Flexion · Extension · Hyper extension · Adduction · Abduction Rotational Movements: Special Movements: · lateral/external rotation · dorsiflexion vs. Plantar flexion · medial/internal rotation · pronation · supination · inversion vs. eversion · opposition · lateral flexion Whats the difference between rotation and circumduction? ↳ circumduction is fixed at a point Classification of Synovial Joints · classified by the type and range of motion that the joint allows · 6 basic categories ① plane/gliding joints ② hinge joints ③ condylar/ellipsoid joints ④ Saddle joints ⑤ pivot joints ⑥ ball-and-socket joints ① Plane/Gliding Joint · bone surfaces are flat or slightly curved · gliding and slight non-axial movements only eg. intercarpal or intertarsal joints, sternoclavicular joint ② Hinge Joint · convex surface of one bone fits into concave surface of second bone · Angular, monoaxial movement (like a door hinge) eg. Knee, elbow, ankle, and interphalangeal joints ③ Pivot joint · rounded surface of bone articulates with ring formed by second bone & ligament · rotational movement only eg. proximal radioulnar joint, Atlanto-axial joint ④ Condyloid/Ellipsoidal Joint · oval shaped projection fits into oval depression · angular, biaxial movement eg. Wrist joint (radiocarpal joint), metatarsophalangeal joints ⑤ Saddle Joint · articular face fit together like a rider and a saddle · each articular face is concave on one axis and convex on the other · biaxial movement eg. first carpometacarpal joint (thumb) ⑥ Ball and Socket Joint · rounded head of one bone (ball) articulates with cup-shaped depression in second bone · multiaxial movement eg. Shoulder joint (glenoid cavity), hip joint (acetabulum) Elbow Joint · complex hinge joint, involves humerus, radius, and ulna · large humeroulnar joint and smaller humeroradial joint · muscles attaching to the rough surface of the olecranon allow for extension of joint · supination of the forearm and flexion of the elbow Knee Joint · complex hinge joint, transfers weight from femur to tibia · includes 3 separate articulations: 2 between condyles of femur and superior surface of tibia, 1 between patella and femur · movements: flexion, extension, limited rotation · Unique joint capsule ↳ medial and lateral mensci (fibrocartilage pads) Shoulder Joint · glenohumeral joint · ball and socket joint, where the head of the humerus articulates with the glenoid cavity of the scapula · largest range of motion of any joint · Specific structures: ↳ glenoid labrum (fibrocartilage lip deepens socket) ↳ rotator cuff (limits ROM to give stability) Hip Joint · strong ball and socket joint · head of the femur articulates with the acetabulum of the hip ↳ contains horseshoe shaped articular cartilage and acetabular labrum · movements: flexion, extension, abduction, adduction, circumduction, rotation · stabilized by surrounding muscles Intervertebral Joints · involves 2 types of joints: ↳ symphyses ↳ synovial · found between vertebrae (axis to sacrum) · intervertebral disks ↳ anulus fibrosus (outer layer) ↳ nucleus pulposus (inner layer) ↳ superior and inferior surfaces covered by thin vertebral end plates made of hyaline cartilage and fibrocartilage · synovial joint between C1 and C2 allow for increased movement · vertebral movements: flexion, extension, lateral flexion, rotation