The Skeletal System: Articulations PDF OCR

The Skeletal System: Articulations 8.1, 8.4, 8.6 Joints (a.k.a. ARTICULATIONS) Where 2 or more bones meet Hold bones together Can provide the skeleton flexibility but some joints DO NOT provide mobility Types of Joints: FUNCTIONAL Synarthroses - Most diarthroses are in immovabl...

The Skeletal System: Articulations 8.1, 8.4, 8.6 Joints (a.k.a. ARTICULATIONS) Where 2 or more bones meet Hold bones together Can provide the skeleton flexibility but some joints DO NOT provide mobility Types of Joints: FUNCTIONAL Synarthroses - Most diarthroses are in immovable the limbs where mobility is important Amphiarthroses - Synarthroses and slightly moveable amphiarthroses mainly found in axial skeleton Diarthroses - freely (firm attachments and moveable protection of internal organs is priority) Types of Joints - STRUCTURAL Fibrous ○ bones joined together by fibrous connective tissue ○ sutures of the skull → immovable Cartilaginous ○ bone ends are connected by cartilage ○ pubic symphysis and intervertebral joints → some immovable and some slightly movable Synovial - freely moveable; only type Fibrous and Cartilaginous Examples Structural Type of Joints: SYNOVIAL Distinguishing features: ○ Articular cartilage: covers ends of bones ○ Fibrous joint capsule composed of dense regular tissue that is continuous with periosteum ○ Joint cavity containing lubricating synovial fluid ○ Reinforcing ligaments ○ Nerves and blood vessels Some nerve fibers detect pain but most monitor joint position and stretch Blood supplies synovial membrane → filtrate from capillaries is basis of synovial fluid Structural Type of Joints: SYNOVIAL Some other features: ○ Fatty pads between fibrous layer and synovial membrane or bone Hip/knee ○ Menisci act as “ball bearings” to reduce friction Flattened fibrous sacs with synovial fluid Occur where ligaments, muscle, skin, tendons or bones rub together ○ Tendon Sheath Elongated that wraps completely around a tendon to reduce friction Common where several tendons are crowded together Factors Influencing Stability Articular surfaces Ligaments ○ More ligaments = stronger the joint ○ Can only stretch 6% before it snaps Muscle tone ○ Most important stabilizing factor Types of Synovial Joints - pg. 230-231 Plane ○ Flat, articular surfaces ○ Gliding, sliding movements ○ Intercarpal joints of the wrist and intertarsal joints of ankles Types of Synovial Joints - pg. 230-231 Hinge ○ Movement in one plane ○ Elbow, joints between phalanges of fingers Types of Synovial Joints - pg. 230-231 Pivot ○ Rotation ○ Rounded end of one bone fits into a sleeve or ring of bone (and possibly ligaments) ○ Ulna and radius ○ Atlas (C1) and axis (C2) Atlas and axis joint = Shake “no” Atlas and skull joint = Nod “yes” Types of Synovial Joints - pg. 230-231 Condyloid ○ “Knuckle-like” ○ Articulating surfaces are oval ○ Metacarpal/ phalangeal joints Types of Synovial Joints - pg. 230-231 Saddle ○ Each articular surface has both convex and concave areas (like a saddle) ○ Carpometacarpal joints of thumbs ○ Ex: Twiddling your thumbs Types of Synovial Joints - pg. 230-231 Ball-and- Socket ○ Most freely moving joints ○ Spherical head of one bone fits into round socket of another ○ Shoulders and hips Common Joint Injuries Cartilage Tears - arthroscopic surgery Sprain - ligaments stretched or torn ○ Partially torn will repair themselves… but slowly! ○ Completely torn: Torn ends can be sewn back together (difficult) Grafts → Piece of tendon from muscle can be attached to bones (ACL) Time and immobilization (MCL) Dislocation - bones forced out of alignment; reduction ○ Repeat dislocations are common Inflammatory Conditions Bursitis - inflammation of bursa ○ Inject anti-inflammatory drugs into bursa ○ Removing fluid by needle aspiration may relieve pressure Tendonitis - inflammation of tendon sheaths ○ Rest, ice, and anti-inflammatory meds Inflammatory and Degenerative Conditions Arthritis - 100 different inflammatory or degenerative diseases that damage the joints! ROOT WORDS! ○ Arthro - joint ○ Itis - inflammation of ○ Could be acute (short term - bacterial infection treated with antibiotics) or chronic (long term) Chronic Arthritis Why haven’t we cured arthritis? Osteoarthritis - “wear and tear arthritis,” affects articular cartilage; slow and irreversible; rarely crippling ○ Treat with pain relievers, moderate exercise, and rest Rheumatoid arthritis - many joints affected at the same time, usually in a symmetrical pattern, autoimmune disease ○ Treat with variety of medicines, exercise to maintain joint mobility, cold packs and heat, and eventually replacement joints as a last resort Gouty arthritis (Gout) - uric acid accumulates in the blood and may be deposited as needle-shaped crystals in the soft tissues of joints, typically affects single joint (often the big toe) ○ Treat with anti-inflammatory meds