Joints (Ar5cula5ons) 8 Joints: Part A site where two or more bones meet Func5ons of joints: Give skeleton Hold skeleton together Func5onal Classifica5on of Joints Based on amount of allowed by the joint Three func5onal classifica5ons: Synarthroses Amphiarthroses Diarthroses Structural Classifica5on of Joints Based on binding bones together and whether or not a joint cavity is present Three classifica5ons: Fibrous Car5laginous Synovial Fibrous Joints Bones joined by connec5ve 5ssue No joint cavity Most are synarthro5c ( ) Three types: Sutures Syndesmoses Gomphoses Fibrous Joints: Sutures Rigid, joints containing short connec5ve 5ssue fibers Allow for growth during youth In middle age, sutures ossify and are called 1
(a) Suture Joint held together with very short, interconnecting fibers, and bone edges interlock. Found only in the skull. Fibrous Joints: Syndesmoses Suture line Dense fibrous connective tissue Figure 8.1a Bones connected by (bands of fibrous 5ssue) Movement varies from immovable to slightly movable Examples: Synarthro5c distal 5biofibular joint Diarthro5c interosseous connec5on between radius and ulna (b) Syndesmosis Joint held together by a ligament. Fibrous tissue can vary in length, but is longer than in sutures. Fibula Tibia Fibrous Joints: Gomphoses Peg- in- socket joints of teeth in alveolar sockets Fibrous connec5on is the periodontal Ligament Figure 8.1b (c) Gomphosis Peg in socket fibrous joint. Periodontal ligament holds tooth in socket. Car5laginous Joints Socket of alveolar process Root of tooth Bones united by car5lage No joint Two types: Periodontal ligament Figure 8.1c 2
Car5laginous Joints: Synchondroses A bar or plate of hyaline car5lage unites the bones All are (a) Synchondroses Bones united by hyaline cartilage Epiphyseal plate (temporary hyaline cartilage joint) Sternum (manubrium) Joint between first rib and sternum (immovable) Figure 8.2a Car5laginous Joints: Symphyses Hyaline car5lage covers the ar5cula5ng surfaces and is to an intervening pad of fibrocar5lage Strong, flexible (b) Symphyses Bones united by fibrocartilage Body of vertebra Fibrocartilaginous intervertebral disc Hyaline cartilage Pubic symphysis Figure 8.2b All are Include all limb joints; most joints of the body 1. Ar5cular car5lage: car5lage 2. Joint ( ) cavity: small poten5al space 3
3. Ar5cular ( ) capsule: Outer fibrous capsule of dense irregular connec5ve 5ssue Inner synovial of loose connec5ve 5ssue 4. fluid: Viscous slippery filtrate of plasma + hyaluronic acid Lubricates and nourishes ar5cular car5lage Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Synovial membrane Periosteum Articular capsule 5. Three possible types of reinforcing ligaments: (intrinsic) part of the fibrous capsule outside the capsule deep to capsule; covered by synovial membrane Figure 8.3 6. Rich and blood vessel supply: Nerve fibers detect pain, monitor joint posi5on and stretch Capillary beds produce filtrate for synovial fluid : Fric5on- Reducing Structures : Flacened, fibrous sacs lined with synovial membranes Contain synovial fluid Commonly act as ball bearings where ligaments, muscles, skin, tendons, or bones 4
Coracoacromial ligament Subacromial bursa Cavity in bursa containing synovial fluid Bursa rolls and lessens friction. Humerus head rolls medially as arm abducts. Humerus resting Humerus moving : Fric5on- Reducing Structures : Elongated bursa that wraps completely around a tendon (b) Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rub against a bone Figure 8.4b Acromion of scapula : Movement Coracoacromial ligament Subacromial bursa Fibrous articular capsule Tendon sheath Tendon of long head of biceps brachii muscle Humerus Joint cavity containing synovial fluid Hyaline cartilage Synovial membrane Fibrous capsule acachments across a joint: Origin acachment to the immovable bone Inser5on acachment to the movable bone Muscle contrac5on causes the inser5on to move toward the origin Movements occur along, frontal, or sagical planes (a) Frontal section through the right shoulder joint Figure 8.4a : Range of Mo5on slipping movements only movement in one plane movement in two planes movement in or around all three planes Movements at 1. 2. : Flexion, extension, hyperextension Abduc5on, adduc5on Circumduc5on 3. Medial and lateral rota5on 5
Movements at 4. Special movements, prona5on Dorsiflexion, plantar flexion of the foot Inversion, Protrac5on, retrac5on Eleva5on, Opposi5on Gliding Movements One flat bone surface glides or another similar surface Examples: Intercarpal joints Intertarsal joints Between ar5cular processes of vertebrae Angular Movements Gliding Movements that occur along the plane: Flexion decreases the angle of the joint Extension increases the angle of the joint excessive extension beyond normal range of mo5on (a) Gliding movements at the wrist Figure 8.5a Hyperextension Extension Extension Flexion Hyperextension Flexion (b) Angular movements: flexion, extension, and hyperextension of the neck Figure 8.5b (c) Angular movements: flexion, extension, and hyperextension of the vertebral column Figure 8.5c 6
Angular Movements Flexion Flexion Extension Extension Movements that occur along the plane: Abduc5on movement away from the midline Adduc5on movement toward the midline flexion + abduc5on + extension + adduc5on of a limb so as to describe a cone in space (d) Angular movements: flexion and extension at the shoulder and knee Figure 8.5d Rota5on Abduction Adduction Circumduction The turning of a bone around its own Examples: Between C 1 and C 2 vertebrae Rota5on of humerus and femur (e) Angular movements: abduction, adduction, and circumduction of the upper limb at the shoulder Figure 8.5e Rotation Lateral rotation Medial rotation Special Movements Movements of around : Supina5on (turning hand backward) Prona5on (turning hand forward) (f) Rotation of the head, neck, and lower limb Figure 8.5f 7
10/26/14 Pronation (radius rotates over ulna) Supination (radius and ulna are parallel) Movements of the : Dorsiflexion (upward movement) Plantar flexion (downward movement) (a) Pronation (P) and supination (S) Figure 8.6a Dorsiflexion Dorsiflexion Movements of the : Inversion (turn sole medially) Eversion (turn sole laterally) Plantar flexion Plantar flexion (b) Dorsiflexion and plantar flexion Figure 8.6b Movements in a plane: Protrac5on (anterior movement) Retrac5on (posterior movement) Inversion Eversion (c) Inversion and eversion Figure 8.6c 8
10/26/14 Eleva5on (lifing a body part ) Depression (moving a body part ) Protraction of mandible Retraction of mandible (d) Protraction and retraction Figure 8.6d Opposi5on of the Movement in the saddle joint so that the thumb touches the 5ps of the other fingers Elevation of mandible Depression of mandible (e) Elevation and depression Figure 8.6e Opposition (f) Opposition Figure 8.6f 9