Section 1 – Classification of Joints (pp. 248-249) Ch 8 – The Joints Section 1 – Classification of Joints (pp. 248-249)

*Joints are the weakest parts of the skeleton Articulation - site where two or more bones come together - known as a joint Functions of joints - Hold skeleton together - give skeleton mobility *Joints are the weakest parts of the skeleton

Functional Classification of Joints Based on amount of movement allowed: 1) Synarthrosis - Generally immovable 2) Amphiarthrosis - Immovable or slightly movable 3) Diarthrosis - Freely movable

Structural Classification of Joints Based on material binding bones together: - Fibrous Joints - Cartilaginous Joints - Synovial Joints *Also involves whether or not joint cavity is present

Section 2 – Fibrous Joints (pp. 249-250) Ch 8 – The Joints Section 2 – Fibrous Joints (pp. 249-250)

Fibrous Joints Fibrous Joints - bones joined by dense fibrous connective tissue - no joint cavity - most are synarthroses (immovable) - Examples 1) Sutures 2) Syndesmoses 3) Gomphoses

Fibrous Joints – Sutures - rigid, interlocking joints - short connective tissue fibers - allow for growth during youth - ossify during middle age - only found in the skull

Fibrous Joints – Syndesmoses - bones connected by ligaments - immovable to slightly moveable Examples *Distal tibiofibular joint *Interosseous connection between radius & ulna

Fibrous Joints – Gomphoses - peg-in-socket joints; teeth - tooth held in by periodontal ligament

Section 3 – Cartilaginous Joints (pp. 250-251) Ch 8 – The Joints Section 3 – Cartilaginous Joints (pp. 250-251)

Cartilaginous Joints Cartilaginous Joints - bones connected by cartilage - no joint cavity Two types: 1) Synchondroses 2) Symphyses

Cartilaginous Joints – Synchondroses - bar or plate of hyaline cartilage binds bones together - all are synarthroses (immovable) Examples: 1) Epiphyseal plates 2) Joint between sternum & first rib

Cartilaginous Joints – Symphyses - strong, flexible amphiarthroses (limited movement) - act as shock absorbers Examples: 1) Intervertebral joints 2) Pubic symphysis (pelvis)

Section 4 – Synovial Joints (pp. 251-253) Ch 8 – The Joints Section 4 – Synovial Joints (pp. 251-253)

Synovial Joints Synovial Joints - all are diarthrotic (freely moveable) - bones separated by fluid-containing joint cavity - lubricated by synovial fluid - include all limb joints; most joints of the body

Features of Synovial Joints Distinguishing features: 1) Articular cartilage - hyaline cartilage that covers the end of bones - decreases friction 2) Joint cavity filled with synovial fluid 3) Articular capsule - strengthens joint - prevents bones from being pulled apart 4) Synovial fluid - thick, very slippery fluid that lubricates joint - thins out as it warms up w/ joint activity

Features of Synovial Joints Distinguishing features: 5) Reinforcing ligaments - help to strengthen & hold joint together 6) Rich nerve & blood vessel supply - nerve fibers detect pain & monitor joint position/stretch - capillary beds help produce synovial fluid

Synovial Joints

Synovial Joints

Synovial Joints

Synovial Joints

Features of Synovial Joints Structures associated w/ synovial joints: 1) Bursae - Flattened, fibrous sacs filled w/ synovial fluid - Provide cushioning - Act as “ball bearings” where ligaments, muscles, skin, tendons, & bones rub together

Features of Synovial Joints Structures associated w/ synovial joints: 2) Tendon sheath - Elongated bursa that wraps around tendon - Protection for tendon

Stabilizing Synovial Joints Factors involved in stabilizing synovial joints: 1) Shape of articular surface - determines what movements are possible - only plays minor role in stability 2) Number of ligaments & their location - prevent excessive & undesirable motion - more ligaments = more strength - limited stability due to inability to stretch; snap easily 3) Muscle tone - most important stabilizing factor - keeps tendons that cross a joint taut

Section 5 – Movements Allowed by Synovial Joints (pp. 253-259) Ch 8 – The Joints Section 5 – Movements Allowed by Synovial Joints (pp. 253-259)

Movement of Synovial Joints General types of movement: 1) Gliding movements - simplest joint movements - one flat bone surface slips/glides over another

Movement of Synovial Joints General types of movement: 2) Angular movements - increase or decrease angle between two bones Examples: a) Flexion - decrease the angle of joint b) Extension - increase the angle of joint c) Hyperextension - excessive extension beyond normal range of motion

Movement of Synovial Joints General types of movement: 2) Angular movements - increase or decrease angle between two bones Examples: d) Abduction - movement away from midline e) Adduction - movement toward midline f) Circumduction - circular motion; cone-shaped

Movement of Synovial Joints General types of movement: 3) Rotation - turning of a bone around its own long axis Examples: a) between C1 (atlas) & C2 (axis) vertebrae b) rotation of humerus & femur

Movement of Synovial Joints Special Movements: 1) Movements of radius around ulna a) Supination - turning palm forward (into anatomical position) b) Pronation - turning palm backward

Movement of Synovial Joints Special Movements: 2) Movements of the foot a) Dorsiflexion - movement of toes upward b) Plantar flexion - movement of toes downward

Movement of Synovial Joints Special Movements: 2) Movements of the foot c) Inversion - turning sole of foot medially d) Eversion - turning sole of foot laterally

Movement of Synovial Joints Special Movements: 3) Non-angular movements in a transverse plane a) Protraction - anterior movement of body part b) Retraction - posterior movement of body part

Movement of Synovial Joints Special Movements: 4) Elevation - lifting a body part superiorly 5) Depression - moving a body part inferiorly

Movement of Synovial Joints Special Movements: 6) Opposition of thumb - touching thumb to tips of other fingers

Section 6 – Types of Synovial Joints (pp. 259) Ch 8 – The Joints Section 6 – Types of Synovial Joints (pp. 259)

Classification of Synovial Joints Six types, based on shape of articular surfaces: 1) Plane Joints - flat articular surfaces - short, gliding movements

Classification of Synovial Joints Six types, based on shape of articular surfaces: 2) Hinge Joints - flexion & extension only - resembles a mechanical hinge

Classification of Synovial Joints Six types, based on shape of articular surfaces: 3) Pivot Joints - rounded end of one bone conforms to a “sleeve” or ring of another bone

Classification of Synovial Joints Six types, based on shape of articular surfaces: 4) Condyloid Joints - both articulating surfaces are oval - permit all angular movements

Classification of Synovial Joints Six types, based on shape of articular surfaces: 5) Saddle Joints - each articular surface has both concave & convex areas - both surfaces shaped like saddles - allow greater freedom of movement than condyloid joints

Classification of Synovial Joints Six types, based on shape of articular surfaces: 6) Ball-and-Socket Joints - spherical head of 1 bone articulates w/ socket of another - most freely moving of all synovial joints

Section 7 – Selected Synovial Joints (pp. 259-264 & 268-269) Ch 8 – The Joints Section 7 – Selected Synovial Joints (pp. 259-264 & 268-269)

Selected Synovial Joints Knee Joint - largest, most complex joint of the body Three joints in one: 1) Femoropatellar joint - plane joint - allows gliding motion of patella over femur during flexion 2 & 3) Tibiofemoral joint (lateral & medial combined) - primarily acts like a hinge permitting flexion & extension - formed by femoral condyles & C-shaped lateral/medial menisci of the tibia A&P Flix™: Movement at the knee joint

Selected Synovial Joints

Selected Synovial Joints Knee Joint - at least 12 associated bursae - articular capsule only present on sides & back of knee - front side reinforced by quadriceps tendon/patellar ligament

Selected Synovial Joints Knee Joint – Ligaments - 3 different kinds of ligaments stabilize & strengthen joint from the OUTSIDE 1) Fibular & tibial collateral ligaments - 1 on each side of knee - work to prevent lateral & medial rotation 2) Oblique popliteal ligament - stabilizes posterior (back) aspect of knee 3) Arcuate popliteal ligament - reinforces the joint capsule posteriorly

Selected Synovial Joints Knee Joint – Ligaments - 2 different kinds of ligaments stabilize & strengthen joint from the INSIDE 1) Anterior Cruciate Ligament (ACL) - prevents forward sliding of the tibia on the femur - works to stop hyperextension of the knee 2) Posterior Cruciate Ligament (PCL) - prevents backward sliding of the tibia Most knee strength/stability is a direct result of heavy reinforcement by muscle tendons… Greater strength & tone of muscles = less chance of injury! Animation: Rotatable knee

Selected Synovial Joints Temporomandibular Joint (TMJ) - “jaw joint” - mandibular condyle articulates with temporal bone - most easily dislocated joint in the body…even by deep yawns Two types of movement: 1) Hinge – depression & elevation of the mandible 2) Gliding – side-to-side grinding of teeth

Section 8 – Homeostatic Imbalances (pp. 269-271) Ch 38 – The Joints Section 8 – Homeostatic Imbalances (pp. 269-271)

(if not repaired, inflammation will turn ligament to mush!) Common Joint Injuries Sprains - ligaments are stretched or torn - partial tears slowly repair themselves - complete ruptures require prompt surgical repair (if not repaired, inflammation will turn ligament to mush!) Cartilage tears - due to compression & sudden direction change - cartilage fragments may cause joint to lock or bind - cartilage is avascular & unable to repair itself - must be repaired by arthroscopic surgery

Common Joint Injuries Dislocations (luxations) - occur when bones are forced out of alignment - accompanied by sprains, inflammation, & joint immobilization - repeat dislocations more likely b/c ligaments become stretched

Inflammatory Joint Conditions Bursitis - Inflammation of bursa - Usually caused by sharp hit or friction - treated with rest, ice, & anti-inflammatory drugs Tendonitis - Inflammation of tendon sheath - caused by overuse of joint

Inflammatory Joint Conditions Arthritis - Inflammatory/degenerative disease of joints - Over 100 types - Most widespread, crippling disease in U.S. - Symptoms = pain, stiffness, & swelling of joint - Acute forms caused by bacteria; treated w/ antibiotics - Chronic forms: Osteoarthritis, Rheumatoid arthritis, & Gouty arthritis

Forms of Arthritis Osteoarthritis - Most common, chronic arthritis; irreversible - Probably related to normal aging process; wear & tear - 85% of all Americans will develop OA; women over men - Cartilage destroyed faster than replaced in overworked joints - Exposed bone ends thicken, enlarge, form bone spurs, & restrict movement

Forms of Arthritis

Forms of Arthritis Rheumatoid Arthritis - Autoimmune disorder…immune system attacks joints - Symptoms begin w/ bilateral inflammation of joint - Usually arises between age 40-50; 3 times more likely in women - Often leads to deformities

Forms of Arthritis

Forms of Arthritis Rheumatoid Arthritis - Treatment 1) Conservative therapy - aspirin, long-term antibiotics, & physical therapy 2) Progressive therapy - anti-inflammatory drugs or immunosuppressants

Forms of Arthritis Gout - Inflammation caused by urate crystals found in blood of people who have difficulty processing proteins - More common in men - If untreated, bone ends may fuse & immobilize joint - Treatment = drugs that help process crystals; lots of water

Section 9 – Developmental Aspects (pp. 272) Ch 8 – The Joints Section 9 – Developmental Aspects (pp. 272)

Developmental Aspects Joint Development - by embryonic week 8, synovial joints resemble adult joints - size, shape, flexibility of joint modified by use As you age… - ligaments, tendons shorten & weaken - intervertebral discs become more likely to herniate - most people have some degree of OA by age 70 **Exercise that puts joints through full range of motion is key to delaying joint problems!