The Skeletal System: Joints

Joints Articulations of bones Functions of joints Hold bones together Allow for mobility Ways joints are classified Functionally- by degree of movement Structurally- by type of connective tissue

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- Synarthroses or Immoveable Bones united by fibrous tissue Example: Sutures Syndesmoses Ligaments attach two bones Allows more movement than sutures Example: Distal end of tibia and fibula Example: Distal end of radium and ulna

Fibrous Joints- Synarthroses or Immoveable Gomphoses- joint created by alveolar processes to hold teeth in

Fibrous Joints Figure 5.28a–b

Cartilaginous Joints Bones connected by cartilage Example: Symphysis joints- fibrocartilage Pubic symphysis Intervertebral joints Synchondroses- hyaline cartilage Connect ribs to sternum

Cartilaginous Joints Figure 5.28c–e

Synovial Joints Most moveable, most numerous, and most complex Articulating bones are separated by a joint cavity Synovial fluid is found in the joint cavity

Synovial Joints Figure 5.28f–h

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 Synovial membrane secretes 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

Synovial Knee Joint

The Synovial Joint Figure 5.29

Types of Synovial Joints Nonaxial Gliding does not involve rotation around axis Plane joint – intercarpal joints of wrist Uniaxial Permit movement on one plane Hinge Joint like jaw, knee, elbow Pivot Joint- 1st and 2nd vertebrae

Types of Synovial Joints Figure 5.30a–c

Types of Synovial Joints Biaxial Permit movements in two planes Saddle joint of thumb Condyloid or ellipsoidal Condyloid on bone fits into ellipsoidal socket like radius and carpal bones Multiaxial Movement in three or more planes Ball and socket joints like hip and shoulder

Types of Synovial Joints Figure 5.30d–f

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 Hyperextension Stretching beyond anatomical position

Types of Ordinary Body Movements Figure 6.13a

Types of Ordinary Body Movements Figure 6.13b

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 Figure 6.13d

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 Figure 6.13c

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

Types of Ordinary Body Movements Figure 6.13d

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

Special Movements Figure 6.13e

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

Special Movements Figure 6.13f

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

Special Movements Figure 6.13g

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

Special Movements Figure 6.13h

Special Movements Protraction- stick something out like jaw Retraction- pull jaw back in Elevation- move something up like close mouth Depression- lower something like the mouth

Joint Replacement Total hip replacement most common orthopedic surgery done on older people

Range of Motion Used to determine degree of damage to an injured joint Active- you move Passive- Dr. moves Goniometer used to measure range of motion ROM greatest early in life

Knee Joint Largest, most complex, and most injured joint Anterior cruciate ligament tear is common Compared to hip, it is relatively unprotected and easily injured Knee injury can be very crippling

Two small puncture wounds Arthroscopy Imaging technique Two small puncture wounds One for tube with lens and small light One with knife

Inflammatory Conditions Associated with Joints Bursitis—inflammation of a bursa usually caused by a blow or friction Dislocation- frequent joint injury Tendonitis—inflammation of tendon sheaths Sprain- injury to ligaments around a joint Strain- overstretching of a muscle

Inflammatory Conditions Associated with Joints 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 Caused by deterioration of cartilage Rheumatoid arthritis An autoimmune disease—the immune system attacks the joints Symptoms begin with bilateral inflammation of certain joints Often leads to deformities More common in women

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 More common in men

Developmental Aspects of the Skeletal System At birth, the skull bones are incomplete Bones are joined by fibrous membranes called fontanels Fontanels are completely replaced with bone within two years after birth

Ossification Centers in a 12-week-old Fetus Figure 5.32

Skeletal Changes Throughout Life Fetus Long bones are formed of hyaline cartilage Flat bones begin as fibrous membranes Flat and long bone models are converted to bone Birth Fontanels remain until around age 2

Skeletal Changes Throughout Life Adolescence Epiphyseal plates become ossified and long bone growth ends Size of cranium in relationship to body 2 years old—skull is larger in proportion to the body compared to that of an adult 8 or 9 years old—skull is near adult size and proportion Between ages 6 and 11, the face grows out from the skull

Skeletal Changes Throughout Life Figure 5.33a

Skeletal Changes Throughout Life Figure 5.33b

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

Advances in Bone Repair Electrical stimulation of fracture sites Bone tissue deposited in places of negative charge Ultrasound- stimulates cartilage cells to make callus Bone Grafting- Take part of bone from hip and put between two bones that have gap Now using vascular fibular grafts

Advances in Bone Repair Bone substitutes Ground cadavar bone ProOsteon from coral Ceramic bone substitutes