Ch. 8 Joints of the Skeletal System

Ch. 8 Joints of the Skeletal System

Part 1: Classifying Joints & Joint Movements Interactive pages 269-278

Types of Joints (AKA: Articulations) Structural Classification (type of tissue that binds the bones Fibrous Cartilaginous Synovial Functional Classification (degree of movement) Synarthrotic Immovable Amphiarthrotic Slightly Moveable Diarthrotic Freely Moveable

Fibrous Joints Bones bound by dense connective tissue (collagen fibers) Types of Fibrous Joints Syndesmosis Bound by a sheet (interosseous membrane) or bundle (interosseous ligament) of Dense C.T. Permits slight movement (amphiarthrosis) such as twisting between the tibia and the fibula Sutures Between plates of the skull (fontanels in infancy) Immovable (synarthrotic) Gomphosis Union of a bony process in a socket (root of tooth attached to mandible or maxilla by periodontal ligament) Immovable

Syndesmosis Suture Gomphosis

Cartilaginous Joints Bones bound by cartilage or fibrocartilage Types of Cartilaginous Joints Synchondrosis Hyaline Cartilage Most Temporary during growth (ex. Epiphyseal plate) Becomes synostosis at maturation Permanent Synchondrosis between manubrium & 1st rib (sternocostal joint) Symphysis Articulating bones covered in hyaline cartilage Connected by a pad of fibrocartilage Ex. Pubic symphysis & intervertebral joints

Synchondrosis Symphysis

Synovial Joints: General Structure Freely Moveable (Diarthrosis) Ends of bones covered in hyaline cartilage called Articular Cartilage Bones held together by joint capsule Outer layer is Dense C.T. fibers attach to periosteum Inner layer is Loose C.T. Synovial membrane Secretes synovial fluid Synovial fluid testing may indicate arthritis, gout, or infection Ligaments reinforce the joint capsule Accessory Structures of the Joint Menisci Pad of fibrocartilage that cushion and distribute weight Bursae Fluid filled sacs that cushion tendons that glide over bones

Synovial Joint Structure Accessory Structures

Synovial Joints: Types Ball & Socket or Spheroidal Wide range of motion (multiaxial movement) Rounded head articulates with cup-shaped cavity of another bone Hip (Acetabulofemoral) & Shoulder (Glenohumeral) Condylar or Ellipsoidal Back and forth/side to Side (biaxial movement) Oval condyle of one bone fits into the elliptical cavity of another Metacarpophalangeal joints Plane or Gliding Sliding and Twisting (nonaxial movement) Flat articulating surfaces Intercarpal & Intertarsal joints

Synovial Joints: Types Hinge One plane of movement (uniaxial) Convex/Concave articulating surfaces Humeroulnar joint and interphalangeal joints Pivot or Trochoid Rotation in one plane (uniaxial) Cylindrical surface of one bone rotates in a ring of bone and ligament Atlantoaxial joint & proximal radioulnar joing Saddle or Sellar Wide range of motion (biaxial) Both bones have a convex and concave surface Carpometacarpal 1

Types of Joint Movements Flexion: Bending at joint to decrease angle Extension Moving at a joint to increase angle Hyperextension Extension beyond anatomical position Abduction Moving part away from midline Adduction Moving part towards midline

Types of Joint Movements Dorsiflexion Movement at ankle that moves anterior foot closer to the shin Plantar flexion Movement at the ankle that moves anterior foot farther from shin Medial rotation Turning limb toward midline Lateral rotation Turning limb away from midline Pronation Rotate forearm to palm down Supination Rotate forearm to palm up Circumduction Moving a part so that the end follows a circular path

Types of Joint Movements Inversion Turning plantar surface medially Eversion Turning plantar surface laterally Protraction Moving a part forward Retraction Moving a part backward Elevation Raising a part Depression Lowering a part

Part 2: Specific Synovial Joints & Disorders Interactive pages 277-288

Examples of Synovial Joints Examples of large, complex synovial (also freely movable) joints: Shoulder. Elbow. Hip. Knee.

Figure 8.13a Shoulder Joint Shoulder Joint: AKA Glenohumeral Joint Ball-and-socket. Head of humerus and glenoid cavity of scapula. Loose joint capsule. Ligaments prevent displacement. Glenoid labrum. Several bursae. Very wide range of movement, including rotation, circumduction.

Major ligaments of the shoulder joint: Coracohumeral ligament. Glenohumeral ligaments. Transverse humeral ligament. Left: Dr. Ronald Bergman

Elbow Joint: Contains 2 articulations: Humeroulnar & Humeroradial Hinge joint: Between trochlea of humerus and trochlear notch of ulna. Flexion / extension only. Plane (gliding) joint: Between capitulum of humerus and fovea on head of radius. Pronation / supination. Several reinforcing ligaments.

Major ligaments of elbow joint: Radial collateral ligament. Ulnar collateral ligament. Anular ligament.

Hip Joint: AKA: Acetabulofemoral Ball-and-socket joint. Head of femur and acetabulum of hip bone. Acetabular labrum. Heavy joint capsule. Many reinforcing ligaments. Variety of movement, yet less than at shoulder joint.

Major ligaments of the hip joint: Iliofemoral ligament (strongest ligament in body). Pubofemoral ligament. Ischiofemoral ligament. Left: Dr. Ronald Bergman

Clinical Application 8.1 Synthetic materials are used to replace joints damaged by arthritis or injury. Steel and titanium replace larger joints, silicone used for smaller joints, some are ceramic. Hip replacements are the most common. New technology for joint replacement: Use of materials that resemble natural body chemicals, such as coating implant with hydroxyapatite. 3D printing technology used to create custom replacement joints.

Knee Joint: AKA: Tibiofemoral Largest & most complex joint. 3 bones: Femur: Medial and lateral condyles of distal end. Tibia: Medial and lateral condyles of proximal end. Patella: Articulates with anterior surface of femur. Strengthened by many ligaments. and tendons. Cushioned by bursae, fat pads. Menisci separate femur and tibia.

Major ligaments of the knee joint: Patellar ligament. Oblique popliteal ligament. Arcuate popliteal ligament. Tibial (medial) collateral ligament. Fibular (lateral) collateral ligament. Anterior cruciate ligament. Posterior cruciate ligament. Knee joint characteristics: Modified hinge joint between condyles. Flexion / extension. Some rotation when knee is flexed. Plane joint between femur & patella.

Joint Disorders Sprains: Tearing of connective tissue in joint, without bone dislocation. Bursitis: Inflammation of a bursa, from overuse or stress. Arthritis: Inflammation, swelling, and pain in a joint. Rheumatoid arthritis: autoimmune disease. Osteoarthritis: degenerative, most common type, occurs with aging. Lyme arthritis: caused by Lyme disease, passed through tick bite.

Lifespan Changes Joint stiffness is an early sign of aging. Many people develop arthritis as they age. Fibrous joints first to change; can strengthen, however, over a lifetime Cartilage in synchondroses stiffens. Ligaments lose elasticity. Changes in symphysis joints of vertebral column diminish flexibility and decrease height (due to water loss from the intervertebral discs). Synovial joints lose function, as capillary supply diminishes. Disuse hampers the nutrient supply to joints; speeds up stiffening. Activity and exercise can keep joints functional longer.