Transcript Synovial Joints

Chapter 08
Lecture Outline
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Introduction
Joints (Articulations):
• Functional junctions between bones
• Bind parts of skeletal system together
• Make bone growth possible
• Permit parts of the skeleton to change shape during childbirth
• Enable body to move in response to skeletal muscle contractions
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8.1: Types of Joints
Structural Classification of Joints:
• Fibrous
• Cartilaginous
• Synovial
Functional Classification of Joints:
• Synarthrotic—immovable
• Amphiarthrotic—slightly movable
• Diarthrotic—freely movable
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Fibrous Joints
Fibrous joints are held together with dense connective tissue containing
many collagen fibers; found in bones in close contact
• There are 3 types of fibrous joints:
• Syndesmosis
• Suture
• Gomphosis
Syndesmosis:
• Bones bound by a sheet of
dense connective tissue
(interosseous membrane) or a
bundle of dense connective tissue
(interosseous ligament)
• Amphiarthrotic (flexible, may twist)
• Lies between tibia and fibula
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Fibrous Joints
Suture:
• Between flat bones of skull
• Thin layer of connective
tissue (sutural ligament)
connects bones
• Synarthrotic (immovable)
Gomphosis:
• Cone-shaped bony process in a
socket in jawbone
• Tooth in jawbone by periodontal
ligament
• Synarthrotic (immovable)
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Cartilaginous Joints
Cartilaginous joints are connected by hyaline cartilage or fibrocartilage
There are 2 types of cartilaginous joints:
• Synchondrosis
• Symphysis
Synchondrosis:
• Bands of hyaline cartilage unite
bones
• Some are temporary, such as
epiphyseal plate (ossification
converts this to a synostosis)
• Between manubrium and the
first rib (costal cartilages,
permanent, synarthrotic)
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Cartilaginous Joints
Symphysis:
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Pad of fibrocartilage between bones
Articular surfaces covered by hyaline cartilage
Amphiarthrotic (limited movement)
Pubic symphysis
Joint between bodies of adjacent vertebrae (intervertebral discs)
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Synovial Joints
Synovial Joints:
• Most joints are synovial joints
• All are diarthrotic joints
• Structure of s synovial joint:
• Articular cartilage covers articular ends of bones
• Joint capsule, consists of 2 layers:
- Outer fibrous layer, composed of ligaments
- Inner layer, synovial membrane, which secretes synovial fluid
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General Structure of Synovial Joints
Synovial joints are more complex than other types of joints, and contain the
following parts:
• Articular cartilage
• Joint capsule
• Ligaments
• Synovial membrane
• Synovial cavity
• Synovial fluid
• Meniscus (-i) in some joints
• Bursa (-ae) in some joints
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General Structure of Synovial Joints
Diagram of the knee joint,
showing typical synovial
joint structures, as well
as less common structures,
such as menisci and bursae
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Types of Synovial Joints
There are 6 types of synovial joints, classified by shape and movements
they allow:
Ball-and-Socket Joint:
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Also called spheroidal joint
Round head in cup-shaped cavity
Widest range of motion
Multiaxial, plus rotation
Hip, shoulder
Condylar Joint:
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Also called ellipsoidal joint
Oval condyle fits into elliptical cavity
Back-and-forth, side-to-side movement
Biaxial movement, no rotation
Joints between metacarpals &
phalanges
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Types of Synovial Joints
Plane Joint:
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Also called gliding joint
Almost flat, or slightly curved
Back-and-forth and twisting
Nonaxial movement
Wrist and ankle joints
Hinge Joint:
• Convex surface fits into concave
surface of other bone
• Uniaxial movement (in 1 plane)
• Elbow, joints between phalanges
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Types of Synovial Joints
Pivot Joint:
• Also called trochoid joint
• Cylindrical surface rotates
within ring of other bone
• Uniaxial movement
• Rotation only
• Atlas (C1) and dens of axis (C2)
Saddle Joint:
• Also called sellar joint
• Both bones have concave and
convex surfaces
• Biaxial movement (in 2 planes)
• Carpal & metacarpal of thumb
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8.2: Types of Joint Movements
• Action of skeletal muscle produces movement at synovial
joints
• Relatively fixed end of a skeletal muscle is called the origin
• More movable end of a skeletal muscle is called the
insertion
• Movement at a joint occurs when a muscle contracts, and its
fibers pull the insertion towards the origin
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Types of Joint Movements
• Abduction / adduction
• Flexion / extension / hyperextension
• Lateral flexion
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Types of Joint Movements
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Dorsiflexion / plantar flexion
Circumduction / rotation
Medial rotation / lateral rotation
Supination / pronation
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Types of Joint Movements
• Inversion / eversion
• Protraction / retraction
• Elevation / depression
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8.3: Examples of Synovial Joints
Examples of large, complex synovial (also freely movable)
joints:
• Shoulder
• Elbow
• Hip
• Knee
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Shoulder Joint
Shoulder Joint:
• Ball-and-socket
• Head of humerus and
glenoid cavity of scapula
• Loose joint capsule
• Ligaments prevent displacement
• Glenoid labrum
• Several bursae
• Very wide range of movement,
including rotation, circumduction
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Shoulder Joint
Major ligaments of the shoulder joint:
• Coracohumeral ligament
• Glenohumeral ligaments
• Transverse humeral ligament
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Elbow Joint
Elbow Joint:
Contains 2 articulations:
• Hinge joint:
- Between trochlea of humerus
and trochlear notch of ulna
- Flexion / extension only
• Plane (gliding) joint:
- Between capitulum of humerus
and fovea on head of radius
- Pronation / supination
• Several reinforcing ligaments
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Elbow Joint
Major ligaments of elbow joint:
• Radial collateral ligament
• Ulnar collateral ligament
• Anular ligament
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Hip Joint
Hip Joint:
• Ball-and-socket joint
• Head of femur and
acetabulum of hip bone
• Acetabular labrum
• Heavy joint capsule
• Many reinforcing ligaments
• Variety of movement, yet less
than at shoulder joint
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Hip Joint
Major ligaments of the hip joint:
• Iliofemoral ligament (strongest ligament in body)
• Pubofemoral ligament
• Ischiofemoral ligament
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Clinical Application 8.1
Replacing Joints
• Synthetic materials are used to replace joints damaged by arthritis or
injury
• Steel and titanium replace larger joints, silicone used for smaller joints,
some are ceramic
• Hip replacements are the most common
• New technology for joint replacement:
- Use of materials that resemble natural body chemicals, such as coating
implant with hydroxyapatite
- 3D printing technology used to create custom replacement joints
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Knee Joint
Knee Joint:
• Largest & most complex joint
• 3 bones:
• Femur: Medial and lateral
condyles of distal end
• Tibia: Medial and lateral
condyles of proximal end
• Patella: Articulates with
anterior surface of femur
• Strengthened by many ligaments
and tendons
• Cushioned by bursae, fat pads
• Menisci separate femur and tibia
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Knee Joint
Major ligaments of the knee joint:
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Patellar ligament
Oblique popliteal ligament
Arcuate popliteal ligament
Tibial (medial) collateral
ligament
• Fibular (lateral) collateral
ligament
• Anterior cruciate ligament
• Posterior cruciate ligament
Knee joint characteristics:
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Modified hinge joint between condyles
Flexion / extension
Some rotation when knee is flexed
Plane joint between femur & patella
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Clinical Application 8.2
Joint Disorders
• Sprains:
Tearing of connective tissue in joint, without bone dislocation
• Bursitis:
Inflammation of a bursa, from overuse or stress
• Arthritis:
Inflammation, swelling, and pain in a joint
- Rheumatoid arthritis: autoimmune disease
- Osteoarthritis: degenerative, most common type, occurs with aging
- Lyme arthritis: caused by Lyme disease, passed through tick bite
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8.4: Lifespan Changes
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Joint stiffness is an early sign of aging
Many people develop arthritis as they age
Fibrous joints first to change; can strengthen, however, over a lifetime
Cartilage in synchondroses stiffens
Ligaments lose elasticity
Changes in symphysis joints of vertebral column diminish flexibility and
decrease height (due to water loss from the intervertebral discs)
• Synovial joints lose function, as capillary supply diminishes
• Disuse hampers the nutrient supply to joints; speeds up stiffening
• Activity and exercise can keep joints functional longer
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