8 P A R T A Joints 1

Joints (Articulations) Articulation – site where two or more bones meet Functions of joints: a. Give the skeleton mobility b. Hold the skeleton together Weakest parts of the skeleton

Classification of Joints: Structural Structural classification focuses material binding bones together whether or not a joint cavity is present The three structural classifications are: Fibrous – no joint cavity; little to no movement Cartilaginous – no joint cavity Synovial – fluid filled joint cavity; freely moveable

Fibrous Structural Joints: Sutures Figure 8.1a

Fibrous Structural Joints: Syndesmoses Figure 8.1b

Cartilaginous Joints: Synchondroses Figure 8.2a, b

Cartilaginous Joints: Symphyses Figure 8.2c

Synovial Joints: General Structure Figure 8.3a, b

Synovial Joints: Friction-Reducing Structures Figure 8.4

Synovial Joints: Movement The two muscle attachments across a joint are: Origin – attachment to the immovable bone Insertion – attachment to the movable bone

One flat bone surface glides or slips over another similar surface Gliding Movements One flat bone surface glides or slips over another similar surface Examples – intercarpal and intertarsal joints, and between the flat articular processes of the vertebrae

Flexion — bending movement that decreases the angle of the joint Angular Movement Flexion — bending movement that decreases the angle of the joint Extension — reverse of flexion; joint angle is increased Dorsiflexion and plantar flexion — up and down movement of the foot

Abduction — movement away from the midline Angular Movement Abduction — movement away from the midline Adduction — movement toward the midline Circumduction — movement describes a cone in space

Gliding Movement Figure 8.5a

Angular Movement Figure 8.5b

Angular Movement Figure 8.5c, d

Angular Movement Figure 8.5e, f

The turning of a bone around its own long axis Rotation The turning of a bone around its own long axis Examples Between first two vertebrae Hip and shoulder joints Figure 8.5g

Supination and pronation Inversion and eversion Special Movements Supination and pronation Inversion and eversion Protraction and retraction Elevation and depression Opposition

Special Movements Figure 8.6a

Special Movements Figure 8.6b

Special Movements Figure 8.6c

Special Movements Figure 8.6d

Special Movements Figure 8.6e

Types of Synovial Joints Plane - intercarpal Hinge joints - elbow Pivot - head Condyloid - wrist Saddle – thumb Ball-and-socket- shoulder

Hinge Joints Figure 8.7b

Pivot Joints Figure 8.7c

Condyloid or Ellipsoidal Joints Figure 8.7d

Saddle Joints Figure 8.7e

Largest and most complex joint of the body Synovial Joints: Knee Largest and most complex joint of the body Allows flexion, extension, and some rotation Three joints in one surrounded by a single joint cavity Femoropatellar joint Lateral and medial tibiofemoral joints

Synovial Joints: Knee Ligaments and Tendons – Anterior View Tendon of the quadriceps femoris muscle Lateral and medial patellar retinacula Fibular and tibial collateral ligaments Patellar ligament Figure 8.8c

Synovial Joints: Knee – Other Supporting Structures Anterior cruciate ligament Posterior cruciate ligament Medial meniscus (semilunar cartilage) Lateral meniscus

Synovial Joints: Knee – Other Supporting Structures Figure 8.8b

Synovial Joints: Elbow Annular ligament Ulnar collateral ligament Radial collateral ligament Figure 8.10a

Synovial Joints: Shoulder Stability Figure 8.11a

Temporomandibular Joint Figure 8.13a, b

The ligaments reinforcing a joint are stretched or torn Sprains The ligaments reinforcing a joint are stretched or torn Partially torn ligaments slowly repair themselves Completely torn ligaments require prompt surgical repair

The snap and pop of overstressed cartilage Cartilage Injuries The snap and pop of overstressed cartilage Common aerobics injury Repaired with arthroscopic surgery

Dislocations Occur when bones are forced out of alignment Usually accompanied by sprains, inflammation, and joint immobilization Caused by serious falls and are common sports injuries Subluxation – partial dislocation of a joint

Inflammatory and Degenerative Conditions Bursitis Tendonitis Arthritis

Arthritis More than 100 different types of inflammatory or degenerative diseases that damage the joints Most widespread crippling disease in the U.S. Symptoms – pain, stiffness, and swelling of a joint Acute forms are caused by bacteria and are treated with antibiotics Chronic forms include osteoarthritis, rheumatoid arthritis, and gouty arthritis