Joints.pdf

Joints Joints Classification of Joints Functional classification (Focuses on amount of movement). Synarthroses (immovable joints). Amphiarthroses (slightly movable joints.) Diarthroses (freely movable joints). Structural classification (Based on the material binding them and presence or absence of a...

Joints Joints Classification of Joints Functional classification (Focuses on amount of movement). Synarthroses (immovable joints). Amphiarthroses (slightly movable joints.) Diarthroses (freely movable joints). Structural classification (Based on the material binding them and presence or absence of a joint cavity). Bony fusion Fibrous Cartilaginous Synovial Joints Functional across Structural down Synarthroses (immovable Amphiarthroses (some movement) joints) Bony fusion Synostosis (frontal=metopic suture; epiphyseal lines) Fibrous Suture (skull only) -fibrous tissue is continuous with periosteum Gomphoses (teeth) ligament is periodontal ligament Cartilagenous (bone united by cartilage only) Synchondroses -hyaline Sympheses -fibrocartilage cartilage (examples: manubrium-C1, epiphyseal (examples: between discs, pubic symphesis plates) Synovial Syndesmoses -ligaments only between bones; here, short so some but not a lot of movement (example: tib-fib ligament) Diarthroses (freely movable) Syndesmoses -ligament longer (example: radioulnar interosseous membrane) Are all diarthrotic Joints Fibrous joints Bones connected by fibrous tissue: dense regular connective tissue. No joint cavity. Slightly immovable or not at all. Types : Sutures Syndesmoses Gomphoses Joints Sutures Only between bones of skull. Fibrous tissue continuous with periosteum. Ossify and fuse in middle age: now technically called “synostoses”= bony junctions Joints Syndesmoses In Greek: “ligament”. Bones connected by ligaments only. Amount of movement depends on length of the fibers: longer than in sutures. Joints Joints Gomphoses Is a “peg-in-socket”. Only example is tooth with its socket. Ligament is a short periodontal ligament. Joints Cartilaginous joints. Articulating bones united by cartilage. Lack a joint cavity. Not highly movable. Two types Synchondroses (singular: synchondrosis). Sympheses (singular: symphesis). Joints Synchondroses Literally: “junction of cartilage”. Hyaline cartilage unites the bones. Immovable (synarthroses). Examples: Epiphyseal plates. Joint between first rib’s costal cartilage and manubrium of the sternum. Joints Sympheses Literally “growing together”. Fibrocartilage unites the bones. Slightly movable (amphiarthroses). Resilient shock absorber. Provide strength and flexibility. Hyaline cartilage on articular surfaces of bones to reduce friction. Examples Intervertebral discs. Pubic symphysis of the pelvis. Joints Also pubic symphysis Joints Synovial joints Include most of the body’s joints. All are diarthroses (freely movable). All contain fluid-filled joint cavity. Joints General Structure of Synovial Joints 1- Articular cartilage Hyaline. Spongy cushions absorb compression. Protects ends of bones from being crushed. 2- Joint (synovial) cavity Potential space. Small amount of synovial fluid. Joints 3- Articular (or joint) capsule Two layered. Outer*: fibrous capsule of dense irregular connective tissue. continuous with periosteum. Inner*: synovial membrane of loose connective tissue (makes synovial fluid). Lines all internal joint surfaces not covered by cartilage. * * * Joints 4- Synovial fluid Filtrate of blood. Contains special glycoproteins. Nourishes cartilage and functions as slippery lubricant. “Weeping” lubrication. 5- Reinforcing ligaments (some joints) Capsular (most) – thickened parts of capsule. Extracapsular. Intracapsular. Joints 6- Nerves Detect pain. Monitor stretch (one of the ways of sensing posture and body movements). 7- Blood vessels Rich blood supply. Extensive capillary beds in synovial membrane (produce the blood filtrate). Joints General structure of synovial joints Joints Some joints… Articular disc or meniscus (literally “crescent”) Only some joints. Those with bone ends of different shapes or fitting poorly. Some to allow two kinds of movement (e.g. jaw) Of fibrocartilage. Examples: knee, TMJ (temporomandibular joint) , Sternoclavicular joint Joints Bursae and Tendon sheaths Contain synovial fluid. Not joints but often associated with them. Act like ball bearings. Bursa means “purse” in Latin. Flattened sac lined by synovial membrane. Where ligaments, muscles, tendons, or bones overlie each other and rub together Tendon sheath. Only on tendons subjected to friction. Joints Bursae and tendon sheaths Joints Joint stability Articular surfaces. Shape usually plays only minor role. Some deep sockets or grooves do provide stability Ligaments. Usually the more, the stronger the joint. Can stretch only 6% beyond normal length before tear. Once stretched, stay stretched. Muscle tone, Constant, low level of contractile force. Keeps tension on the ligaments. Especially important at shoulders, knees, arches of foot. Joints Movements allowed by synovial joints Gliding Angular movements: ⬆️ or ⬇️ the angle between two bones Flexion Extension Abduction Adduction Circumduction Rotation Special movements Joints Special movements : Pronation Supination Dorsiflexion Plantar flexion Inversion Eversion Protraction Retraction Elevation Depression Opposition Joints Joints Joints Joints Joints Joints Joints Synovial joints classified by shape (of their articular surfaces) Plane acromioclavicular, wrist (radio carpal), ankle (tarsal joints). Hinge interphalangeal joints of the hand and foot, humerus and ulna, elbow, knee, ankle joint. Pivot Proximal and distal radioulnar joint atlanto-axial joint Joints Synovial joints classified by shape (of their articular surfaces) Condyloid the metacarpophalangeal joints, metatarsophalangeal joints. Saddle the carpals and metacarpals of thumb and the trapezium. Ball-and-socket shoulder joint, and hip joint. Joints Joints Shoulder (glenohumeral) joint Stability sacrificed for mobility. Ball and socket: head of humerus with glenoid cavity of scapula. Glenoid labrum: rim of fibrocartilage. Thin, loose capsule. Strongest ligament: coracohumeral. Muscle tendons help stability. Has Disorders. Biceps tendon is intra-articular. Rotator cuff muscles add to stability Joints Joints Elbow joint Hinge: allows only flexion and extension Annular ligament of radius attaches to capsule. Capsule thickens into: Radial collateral ligament. Ulnar collateral ligament. Muscles cross joint. Trauma. Joints Wrist joint Two major joint surfaces. Several ligaments stabilize. Radiocarpal joint Between radius and proximal carpals (scaphoid and lunate). Condyloid joint. Flexion extension adduction, abduction, circumduction. Intercarpal or midcarpal joint Between the proximal and distal rows of carpals saddle joint. Joints Hip (coxal) joint Ball and socket Moves in all axes but limited by ligaments and deep socket. Three ext. ligaments “screw in” head of femur when standing. Iliofemoral. Pubofemoral. Ischiofemoral. Joints Acetabular labrum diameter smaller than head of femur. Dislocations rare. Ligament of head of femur supplies artery. Muscle tendons cross joint. Hip fractures common in elderly because of osteoporosis. Joints Right hip, AP view Joints Knee joint Largest and most complex joint. Primarily a hinge. Compound and bicondyloid: femur and tibia both have 2 condyles Femoropatellar joint shares joint cavity. At least a dozen bursae: Prepatellar. Suprapatellar. Joints Lateral and medial menisci “Torn cartilage”. Capsule absent anteriorly. Capsular and extracapsular ligaments. Taut when knee extended to prevent hyperextension. Joints Joints Joints Patellar ligament Continuation of quad tendon. Medial and lateral retinacula. Fibular and tibial collateral ligaments. Called medial and lateral. Extracapsular. Oblique popliteal. Arcuate popliteal. Joints Cruciate ligaments Cross each other (cruciate means cross). Anterior cruciate (ACL): Anterior intercondylar area of tibia to medial side of lateral condyle of femur. Posterior cruciate (PCL): Posterior intercondylar area of tibia to lateral side of medial condyle. Restraining strap. Lock the knee. Joints Cruciate ligaments Joints Ankle joint Hinge joint. Distal tibia and fibula to talus. Dorsiflexion and plantar flexion only. Medial deltoid ligament. Lateral ligaments: 3 bands. Anterior talofibular. Posterior talofibular. Calcaneofibular. Anterior and posterior tibiofibular (syndesmosis). Joints Joints Joints Temporomandibular joint (TMJ) Head of mandible articulates with temporal bone. Disc protects thin mandibular fossa of temporal bone. Many movements. Demonstrate movements together. Disorders common. Joints Sternoclavicular joint Saddle joint. Only other example is trapezium and metacarpal 1 (thumb), allowing opposion. Sternum and 1st costal (rib) cartilage articulate with clavicle. Very stable: clavicle usually breaks before dislocation of joint. Only bony attachment of axial skeleton to pectoral girdle. Demonstrate movements together.