Joints
Classifications 2 ways to classify: 1) Functional 2) Structural
Functional Classification: Immovable joints- Synarthroses Slightly moveable- Amphiarthroses Freely moveable- Diarthroses
Structural Classification: 1) Fibrous- joined by fibrous tissue- immovable example: Sutures- of the skull Syndesmoses- interosseous Gomphoses- tooth sockets
2) Cartilaginous- united by cartilage Examples: Synchondroses- epiphyseal plates Symphyses- pubic, intervertebral discs
3. Synovial- all those joints that have the bones separated by a fluid containing joint cavity
All Synovial joints have: 1. Articular cartilage (hyaline) 2. Joint (synovial) cavity 3. Articular capsule (double layer) 4. Synovial membrane 5. Synovial Fluid (secreted by the membrane) 6. Reinforcing ligaments
Synovial Joint
Certain synovial joints also have: 1. Bursa- flattened fibrous sacs of lubricant 2. Tendon Sheaths- an elongated bursa that wraps completely around a tendon
Factors that influence stability: 1. Articular surfaces- the way the bones fit together 2. Ligaments- the more the better 3. Muscle tone- keeps tendons tight
Types of Synovial Joints Plane Joints – gliding joints – carpals Hinge joint- elbow, finger Pivot joint- atlas / axis Saddle Joint- thumb Ball and Socket Joint- shoulder, hip
Movements: Gliding- between the carpals, tarsals, vertebrae Flexion- decrease angle, bring bones together Extension- increase angle, bring bones apart Dorsiflexion- toe points up Plantar flexion- toe points down Abduction- move limb away from midline Adduction- move limb toward midline
Movements Continued Circumduction- move a limb in a cone in space Rotation- turning a bone around it’s axis Supination- move hand into anatomical position Pronation- move hand medial, palm face back Inversion- move foot medially Eversion- move foot laterally Protraction- anterior non lateral movement Retraction- posterior non angular movement
Movements Continued Elevation- lift the body part superior Depression- move the body part inferior Opposition- movement of thumb
Shoulder Joint Glenohumeral joint Loose joint= free movement= instability
Shoulder Joint Consists of: Glenoid labrum Corocohumeral ligament Glenohumeral ligaments (3) Transverse humeral ligaments (3) Also has several bursae
The greatest contribution to shoulder stability is the muscle tendons: Long head of the biceps brachi- secures the head of the humerus tightly against the glenoid cavity. 4 other tendons: Subscapularis Supraspinatus Rotator Cuff Infraspinatus Teres minor
Shoulder The Rotator Cuff can be severely stretched when subjected to vigorous circumduction-Example: Baseball
Hip (Coxal) Joint Less free movement = higher stability Ligaments: Labrum acetabular Iliofemeral ligament Pubofemoral ligament Ischiofemoral ligament Most tendons of bulky hip and thigh muscles contribute to the stability
Elbow Joint Flexion and extension – No side to side movement Capsule surrounded by annular ligament Ulnar collateral ligament (medial) Radial collateral ligament (lateral) Tendons of several muscles- biceps, triceps, brachialis,- to reinforce it.
Knee Joint Largest, Most Complex Extension, flexion, some rotation Includes the Femoral- patella joint -where the patella glides over the femur
The knee normally acts as a hinge joint permitting extension and flexion When it is partially flexed some side movement is possible When it is extended, the ligaments resist side to side or rotation
The knee joint capsule is incomplete- anterior side is open posterior and sides are enclosed by a thin joint capsule Anterior is the patella and the patella ligament There are also a dozen bursae
Around the outside of the incomplete capsule are ligaments: Fibular collateral ligaments- lateral from lateral epicondyle of the femur to head of fibula Tibial collateral ligaments- medial -from medial epicondyle of the femur to medial condyle of tibia Oblique popliteal ligament- posterior Arcuate popliteal ligament- posterior
Ligaments inside the capsule- intracapsular Cruciate ligaments form X within the notch between the condyles They prevent anterior/posterior displacement Anterior Cruciate Ligament- anterior tibia to posterior medial side of lateral condyle of the femur Posterior Cruciate Ligament- posterior tibia to anterior lateral side of the medial condyle of the femur (stronger)
Knee capsule is heavily reinforced by muscle and tendons: Strong tendons of quadriceps, semimembranous Meniscus (semilunar cartrilage) are attached at the ends of the tibia Prevent side to side rocking Absorb shock
Knee Injury The knee can absorb vertical impact It is susceptible to side to side or twisting impact Most likely to tear: in order 1) medial collateral ligament 2) medial meniscus 3) Anterior Cruciate Ligament (ACL)
Joint Imbalances Sprains- ligaments are stretched or torn, they heal slowly, if torn they may need to be surgically repaired Cartilage injuries- damage to articular cartilage can be corrected by arthroscopic surgery Dislocation- bones are forced out of their normal location. Repeats are common because the joint and ligaments stretch
Inflammation Bursitis- inflammation of a bursa caused by direct injury or friction Tendonitis- inflammation of a tendon sheath Arthritis- inflammatory or degenerative diseases that affects joints
3 types of Arthritis 1. Osteoarthritis- (OA) most common, degenerative joint disease, associated with aging , athletes Breakdown of articular cartilage, Exposed bone forms spurs and resis movements, stiffness on rising Most common in hands, cervical vertebrae, lumbar, and weight bearing knees and hips Bone make cracking noises Slow, irreversible course
Autoimmune 2. Rheumatoid Arthritis- (RA) Chronic inflammatory disorder, auto immune disease - body attacks it’s own tissue Affects fingers, wrist, ankles, feet, small joints Begins with inflammation of synovial joint because of bacteria or virus, attacks cartilage, causes swelling, stiffness, scar tissue, bent fingers
Patient with RA
Gout 3. Gouty Arthritis- uric acid in the blood rise and crystals are deposited in the soft tissue of the joint Causes acutely painful attacks (usually in the big toe)