Joints Articulations of bones Functions of joints All joints hold bones together Allow for mobility Ways joints are classified Functionally Structurally

Functional Classification of Joints Synarthroses Immovable joints Amphiarthroses Slightly moveable joints Diarthroses Freely moveable joints

Structural Classification of Joints Fibrous joints Generally immovable Cartilaginous joints Immovable or slightly moveable Synovial joints Freely moveable

Summary of Joint Classes [Insert Table 5.3 here] Table 5.3

Fibrous Joints Bones united by fibrous tissue Example: Sutures Syndesmoses Allows more movement than sutures Example: Distal end of tibia and fibula

Cartilaginous Joints Bones connected by cartilage Example: Pubic symphysis Intervertebral joints

Synovial Joints Articulating bones are separated by a fibrous articular joint cavity Synovial fluid is found in the joint cavity Include hip, knee, elbow joints

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Features of Synovial Joints Articular cartilage (hyaline cartilage) covers the ends of bones A fibrous articular capsule encloses joint surfaces A joint cavity is filled with synovial fluid Ligaments reinforce the joint

Structures Associated with the Synovial Joint Bursae—flattened fibrous sacs Lined with synovial membranes Filled with synovial fluid Not actually part of the joint Tendon sheath Elongated bursa that wraps around a tendon Ligament reinforce articular capsule

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The Synovial Joint Figure 5.29 Reinforce articular capsule Fluid filled synovial membrane sacs Reinforce articular capsule Covers the ends of bones Lines the articular capsule Figure 5.29

Types of Synovial Joints Sliding movements in one or two planes (uni-or biaxial Allows movement in one plane (uniaxial) uniaxial Intercarpal (between carpal bones) Elbow (humerus /ulna) Interphalange (between phalanges) Ulna / Radius Atlas/axis Figure 5.30a–c

Types of Synovial Joints biaxial biaxial multiaxial Metacarpal bones/ proximal phalanges (knuckles) Forearm bones/ wrist Skull/ vertebral column Wrist joint Thumb metacarpal and trapezium (a carpal) Shoulder joint Hip joint Figure 5.30d–f

Hip vs Knee Joint Hip joint is more stable than the knee joint Hip Is a multiaxial joint Allows movement in all directions Knee allows movement in one plane (uniaxial)

Five Golden Rules of Skeletal Muscle Activity Table 6.2

Muscles and Body Movements Movement is attained due to a muscle moving an attached bone Muscles are attached to at least two points Origin Attachment to a moveable bone Insertion Attachment to an immovable bone

Muscles and Body Movements Figure 6.12

Types of Ordinary Body Movements Flexion Decreases the angle of the joint Brings two bones closer together Typical of hinge joints like knee and elbow Extension Opposite of flexion Increases angle between two bones

Types of Ordinary Body Movements Figure 6.13b

Types of Ordinary Body Movements Rotation Movement of a bone around its longitudinal axis Common in ball-and- socket joints Example is when you move atlas around the dens of axis (shake your head “no”)

Types of Ordinary Body Movements Abduction Movement of a limb away from the midline Adduction Opposite of abduction Movement of a limb toward the midline

Types of Ordinary Body Movements Circumduction Combination of flexion, extension, abduction, and adduction Common in ball-and-socket joints

Special Movements Dorsiflexion Plantar flexion Lifting the foot so that the superior surface approaches the shin Plantar flexion Depressing the foot (pointing the toes)

Special Movements Inversion Eversion Turn sole of foot medially Turn sole of foot laterally

Special Movements Supination Pronation Forearm rotates laterally so palm faces anteriorly Pronation Forearm rotates medially so palm faces posteriorly

Special Movements Opposition Move thumb to touch the tips of other fingers on the same hand

Inflammatory Conditions Associated with Joints Bursitis—inflammation of a bursa usually caused by a blow or friction Tendonitis—inflammation of tendon sheaths Arthritis—inflammatory or degenerative diseases of joints Over 100 different types The most widespread crippling disease in the United States

Clinical Forms of Arthritis Osteoarthritis Most common chronic arthritis Probably related to normal aging processes Softening, fraying and eventual breakdown of cartilage leading to bone spurs (excess bone tissue) Rheumatoid arthritis An autoimmune disease—the immune system attacks the joints Symptoms begin with bilateral inflammation of certain joints Often leads to deformities

Clinical Forms of Arthritis Gouty arthritis Inflammation of joints is caused by a deposition of uric acid crystals from the blood Can usually be controlled with diet

Skeletal Changes Throughout Life Osteoporosis Bone-thinning disease afflicting 50% of women over age 65 20% of men over age 70 Disease makes bones fragile and bones can easily fracture Vertebral collapse results in kyphosis (also known as dowager’s hump) Estrogen aids in health and normal density of a female skeleton

Skeletal Changes Throughout Life Figure 5.34

Skeletal Changes Throughout Life Figure 5.35

Dislocation of joint A dislocation is a separation of two bones where they meet at a joint. A dislocated bone is no longer in its normal position, which may result in damage to ligaments, nerves, and blood vessels. Dislocation of the shoulder joint is common and occurs when the top part of arm bone slips out of its socket Radial dislocation may be caused by a sudden pull on a child's arm or hand. For first aid, immobilize the arm and take the child to the doctor's office or emergency room.