Articulations and Joints Muse lecture #9 6/11/12

Joints Chapter 9  Joint Classifications  Fibrous Joints  Cartilaginous Joints  Synovial Joints  Types of Movements at Synovial Joints  Types of Synovial Joints  Factors Affecting Contact and Range of Motion at Synovial Joints  Selected Joints of the Body  Aging and Joints  Arthroplasty Muse Lecture #6

An Introduction to Articulations  Articulations  Body movement occurs at joints (articulations) where two bones connect  Joint Structure  Determines direction and distance of movement (range of motion)  Joint strength decreases as mobility increases

Classification of Joints  Two methods of classification  Functional classification is based on range of motion of the joint  Structural classification relies on the anatomical organization of the joint

Classification of Joints  Functional Classifications  Synarthrosis (immovable joint)  No movement  Fibrous or cartilaginous connections  May fuse over time  Amphiarthrosis (slightly movable joint)  Little movement  Fibrous or cartilaginous connections  Diarthrosis (freely movable joint)  More movement  Also called synovial joints  Subdivided by type of motion Party on Arth!

Classification of Joints

 Structural Classifications  Bony  Fibrous  Cartilaginous  Synovial (capsulated)

Classification of Joints

 Functional Classifications  Synarthroses (immovable joints)  Are very strong  Edges of bones may touch or interlock  Four types of synarthrotic joints: –suture –gomphosis –synchondrosis –synostosis

Classification of Joints  Synarthrotic Joints  Suture  Bones interlocked  Are bound by dense fibrous connective tissue  Are found only in skull  Gomphosis  Fibrous connection (periodontal ligament)  Binds teeth to sockets Yah can’t chomp without the gomph

Joints (Fibrous Joints)  Sutures  Occur only between bones of the skull  Syndesmoses  Permits slight movement  Interosseous membrane  Between the tibia and fibula in the leg  Gomphoses  Immovable joint  Joint in which a cone-shaped peg fits into a socket  Articulations of the teeth with the sockets of the maxillae and mandible

Figure 8.1b Fibula Tibia Ligament (b) Syndesmosis Joint held together by a ligament. Fibrous tissue can vary in length, but is longer than in sutures.

Joints (Fibrous Joints)  Lack a synovial cavity  The articulating bones are held very closely together by dense irregular connective tissue  Fibrous joints permit little or no movement  Three types of fibrous joints  Sutures  Syndesmoses  Gomphoses

Classification of Joints  Synarthrotic Joints  Synchondrosis  Is a rigid cartilaginous bridge between two bones: –epiphyseal cartilage of long bones –between vertebrosternal ribs and sternum  Synostosis  Fused bones, immovable: –metopic suture of skull –epiphyseal lines of long bones

Classification of Joints  Functional Classifications  Amphiarthroses  More movable than synarthrosis  Stronger than freely movable joint  Two types of amphiarthroses –syndesmosis: »bones connected by ligaments –symphysis: »bones separated by fibrous cartilage

Classification of Joints  Functional Classifications  Synovial joints (diarthroses)  Also called movable joints  At ends of long bones  Within articular capsules  Lined with synovial membrane

Synovial Joints  Components of Synovial Joints  Articular cartilages  Pad articulating surfaces within articular capsules: –prevent bones from touching  Smooth surfaces lubricated by synovial fluid: –reduce friction

Figure 8.3 Periosteum Ligament Fibrous capsule Synovial membrane Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Articular capsule

Synovial Joints  Components of Synovial Joints  Synovial fluid  Contains slippery proteoglycans secreted by fibroblasts  Functions of synovial fluid: –lubrication –nutrient distribution –shock absorption

Synovial Joints  Components of Synovial Joints  Accessory structures  Cartilages: –cushion the joint: »Fibrous cartilage pad called a meniscus (articular disc)  Fat pads: –superficial to the joint capsule –protect articular cartilages  Ligaments: –support, strengthen joints –sprain: ligaments with torn collagen fibers

Synovial Joints  Components of Synovial Joints  Accessory structures  Tendons: –attach to muscles around joint –help support joint  Bursae: –pockets of synovial fluid –cushion areas where tendons or ligaments rub

Figure 8.4b Coracoacromial ligament Subacromial bursa Cavity in bursa containing synovial fluid Bursa rolls and lessens friction. Humerus head rolls medially as arm abducts. (b) Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rub against a bone Humerus resting Humerus moving

Synovial Joints  Factors That Stabilize Synovial Joints  Prevent injury by limiting range of motion  Collagen fibers (joint capsule, ligaments)  Articulating surfaces and menisci  Other bones, muscles, or fat pads  Tendons of articulating bones

Synovial Joints [INSERT FIG. 9.1a] Figure 9–1a The Structure of a Synovial Joint.

Synovial Joints Figure 9–1b The Structure of a Synovial Joint.

Synovial Joints  Injuries  Dislocation (luxation)  Articulating surfaces forced out of position  Damages articular cartilage, ligaments, joint capsule  Subluxation  A partial dislocation

Movements  Types of Dynamic Motion  Linear motion (gliding)  Angular motion  Rotation  Planes (Axes) of Dynamic Motion  Monaxial (1 axis)  Biaxial (2 axes)  Triaxial (3 axes)

Movements Figure 9–2 A Simple Model of Articular Motion.

Movements Figure 9–2 A Simple Model of Articular Motion.

Movements  Types of Movements at Synovial Joints  Terms describe  Plane or direction of motion  Relationship between structures

Movements  Types of Movements at Synovial Joints  Linear motion  Also called gliding  Two surfaces slide past each other: –between carpal or tarsal bones

Movements  Angular Motion  Flexion  Angular motion  Anterior–posterior plane  Reduces angle between elements  Extension  Angular motion  Anterior–posterior plane  Increases angle between elements

Movements  Angular Motion  Hyperextension  Angular motion  Extension past anatomical position Angular Movements

Movements Figure 9–3a Angular Movements.

Movements  Angular Motion  Abduction  Angular motion  Frontal plane  Moves away from longitudinal axis  Adduction  Angular motion  Frontal plane  Moves toward longitudinal axis Think adding Think kidnapping

Movements Figure 9–3 Angular Movements.

Movements Figure 9–3 Angular Movements.

Movements  Angular Motion  Circumduction  Circular motion without rotation  Angular motion

Movements Figure 9–3 Angular Movements.

Movements  Types of Movement at Synovial Joints  Rotation  Direction of rotation from anatomical position  Relative to longitudinal axis of body  Left or right rotation  Medial rotation (inward rotation): –rotates toward axis  Lateral rotation (outward rotation): –rotates away from axis

Movements Figure 9–4a Rotational Movements.

Movements  Types of Movements at Synovial Joints  Rotation  Pronation: –rotates forearm, radius over ulna  Supination: –forearm in anatomical position

Movements Figure 9–4b Rotational Movements.

Movements  Types of Movements at Synovial Joints  Special movements  Inversion: –twists sole of foot medially  Eversion: –twists sole of foot laterally  Dorsiflexion: –flexion at ankle (lifting toes)  Plantar flexion: –extension at ankle (pointing toes) Plant your feet

Movements  Special Movements at Synovial Joints  Opposition  Thumb movement toward fingers or palm (grasping)  Protraction  Moves anteriorly  In the horizontal plane (pushing forward)  Retraction  Opposite of protraction  Moving anteriorly (pulling back)

Movements  Special Movements at Synovial Joints  Elevation  Moves in superior direction (up)  Depression  Moves in inferior direction (down)  Lateral flexion  Bends vertebral column from side to side

Movements Figure 9–5 Special Movements.

Movements Figure 9–5 Special Movements.

Movements  Classification of Synovial Joints by Shape  Gliding  Hinge  Pivot  Ellipsoid  Saddle  Ball-and-socket A Functional Classification of Synovial Joints

Movements  Gliding Joints  Flattened or slightly curved faces  Limited motion (nonaxial)  Hinge Joints  Angular motion in a single plane (monaxial)  Pivot Joints  Rotation only (monaxial)

Movements Figure 9–6 Movements at Synovial Joints.

Movements  Ellipsoid Joints  Oval articular face within a depression  Motion in two planes (biaxial)  Saddle Joints  Two concave, straddled (biaxial)  Ball-and-Socket Joints  Round articular face in a depression (triaxial)

Movements Figure 9–6 Movements at Synovial Joints.

Movements  A joint cannot be both mobile and strong  The greater the mobility, the weaker the joint  Mobile joints are supported by muscles and ligaments, not bone-to-bone connections

Intervertebral Articulations  Intervertebral Articulations  C 2 to L 5 spinal vertebrae articulate  At inferior and superior articular processes (gliding joints)  Between adjacent vertebral bodies (symphyseal joints)

Intervertebral Articulations  Intervertebral Articulations  C 2 to L 5 spinal vertebrae articulate  Intervertebral discs: –pads of fibrous cartilage –separate vertebral bodies –anulus fibrosus: »tough outer layer »attaches disc to vertebrae –nucleus pulposus: »elastic, gelatinous core »absorbs shocks

Intervertebral Articulations Figure 9–7 Intervertebral Articulations.

Intervertebral Articulations  Vertebral Joints  Also called symphyseal joints  As vertebral column moves  Nucleus pulposus shifts  Disc shape conforms to motion  Intervertebral Ligaments  Bind vertebrae together  Stabilize the vertebral column

Intervertebral Articulations  Six Intervertebral Ligaments  Anterior longitudinal ligament  Connects anterior bodies  Posterior longitudinal ligament  Connects posterior bodies  Ligamentum flavum  Connects laminae

Intervertebral Articulations  Six Intervertebral Ligaments  Interspinous ligament  Connects spinous processes  Supraspinous ligament  Connects tips of spinous processes (C 7 to sacrum)  Ligamentum nuchae  Continues supraspinous ligament (C 7 to skull)

Intervertebral Articulations  Damage to Intervertebral Discs  Slipped disc  Bulge in anulus fibrosus  Invades vertebral canal  Herniated disc  Nucleus pulposus breaks through anulus fibrosus  Presses on spinal cord or nerves

Intervertebral Articulations Figure 9–8a Damage to the Intervertebral Discs.

Intervertebral Articulations Figure 9–8b Damage to the Intervertebral Discs.

Intervertebral Articulations  Movements of the Vertebral Column  Flexion  Bends anteriorly  Extension  Bends posteriorly  Lateral flexion  Bends laterally  Rotation  Turning

Articulations of the Axial Skeleton

Joints (Selected Joints of the Body)  Temporomandibular Joint  Combined hinge and planar joint formed by the mandible and the temporal bone  Only movable joint between skull bones  Only the mandible moves

Figure 8.13c Lateral excursion: lateral (side-to-side) movements of the mandible Outline of the mandibular fossa Superior view

Figure 8.13a Zygomatic process Mandibular fossa Articular tubercle Infratemporal fossa External acoustic meatus Articular capsule Ramus of mandible Lateral ligament (a) Location of the joint in the skull

Figure 8.13b Articular capsule Mandibular fossa Articular disc Articular tubercle Superior joint cavity Inferior joint cavity Mandibular condyle Ramus of mandible Synovial membranes (b) Enlargement of a sagittal section through the joint

The Shoulder Joint  Also called the glenohumeral joint  Allows more motion than any other joint  Is the least stable  Supported by skeletal muscles, tendons, ligaments  Ball-and-socket diarthrosis  Between head of humerus and glenoid cavity of scapula

The Shoulder Joint  Socket of the Shoulder Joint  Glenoid labrum  Deepens socket of glenoid cavity  Fibrous cartilage lining  Extends past the bone  Processes of the Shoulder Joint  Acromion (clavicle) and coracoid process (scapula)  Project laterally, superior to the humerus  Help stabilize the joint

The Shoulder Joint  Shoulder Ligaments  Glenohumeral  Coracohumeral  Coraco-acromial  Coracoclavicular  Acromioclavicular  Shoulder Separation  Dislocation of the shoulder joint

The Shoulder Joint  Shoulder Muscles (also called rotator cuff)  Supraspinatus  Infraspinatus  Subscapularis  Teres minor  Shoulder Bursae  Subacromial  Subcoracoid  Subdeltoid  Subscapular

The Shoulder Joint Figure 9–9a The Shoulder Joint.

The Shoulder Joint Figure 9–9b The Shoulder Joint.

The Elbow Joint  A stable hinge joint  With articulations involving humerus, radius, and ulna

The Elbow Joint  Articulations of the Elbow  Humero-ulnar joint  Largest articulation  Trochlea of humerus and trochlear notch of ulna  Limited movement  Humeroradial joint:  Smaller articulation  Capitulum of humerus and head of radius

The Elbow Joint Figure 9–10a The Elbow Joint.

The Elbow Joint  Supporting Structures of the Elbow  Biceps brachii muscle  Attached to radial tuberosity  Controls elbow motion  Elbow Ligaments  Radial collateral  Annular  Ulnar collateral

The Elbow Joint Figure 9–10b The Elbow Joint.

The Hip Joint  Also called coxal joint  Strong ball-and-socket diarthrosis  Wide range of motion

The Hip Joint  Structures of the Hip Joint  Head of femur fits into it  Socket of acetabulum  Which is extended by fibrocartilaginous acetabular labrum  Ligaments of the Hip Joint  Iliofemoral  Pubofemoral  Ischiofemoral  Transverse acetabular  Ligamentum teres

The Hip Joint Figure 9–11a The Hip Joint.

The Hip Joint Figure 9–11b The Hip Joint.

The Hip Joint Figure 9–11c The Hip Joint.

The Knee Joint  A complicated hinge joint  Transfers weight from femur to tibia  Articulations of the knee joint  Two femur–tibia articulations  At medial and lateral condyles  One between patella and patellar surface of femur

The Knee Joint  Menisci of the Knee  Medial and lateral menisci  Fibrous cartilage pads  At femur–tibia articulations  Cushion and stabilize joint  Give lateral support  Locking knees  Standing with legs straight: –“locks” knees by jamming lateral meniscus between tibia and femur

The Knee Joint  Seven Ligaments of the Knee Joint  Patellar ligament (anterior)  Two popliteal ligaments (posterior)  Anterior and posterior cruciate ligaments (inside joint capsule)  Tibial collateral ligament (medial)  Fibular collateral ligament (lateral)

The Knee Joint Figure 9–12a The Knee Joint.

The Knee Joint Figure 9–12b The Knee Joint.

The Knee Joint Figure 9–12c The Knee Joint.

The Knee Joint Figure 9–12d The Knee Joint.

Figure 8.14 Torn meniscus

The Knee Joint

Aging  Rheumatism  A pain and stiffness of skeletal and muscular systems  Arthritis  All forms of rheumatism that damage articular cartilages of synovial joints  Osteoarthritis  Caused by wear and tear of joint surfaces, or genetic factors affecting collagen formation  Generally in people over age 60

Developmental Aspects of Joints  By embryonic week 8, synovial joints resemble adult joints  A joint’s size, shape, and flexibility are modified by use  Advancing years take their toll on joints:  Ligaments and tendons shorten and weaken  Intervertebral discs become more likely to herniate  Most people in their 70s have some degree of OA  Exercise that coaxes joints through their full range of motion is key to postponing joint problems

Aging  Rheumatoid Arthritis  An inflammatory condition  Caused by infection, allergy, or autoimmune disease  Involves the immune system  Gouty Arthritis  Occurs when crystals (uric acid or calcium salts)  Form within synovial fluid  Due to metabolic disorders

Rheumatoid Arthritis  RA begins with synovitis of the affected joint  Inflammatory blood cells migrate to the joint, release inflammatory chemicals  Inflamed synovial membrane thickens into a pannus  Pannus erodes cartilage, scar tissue forms, articulating bone ends connect (ankylosis)

Figure 8.15

Gouty Arthritis  Deposition of uric acid crystals in joints and soft tissues, followed by inflammation  More common in men  Typically affects the joint at the base of the great toe  In untreated gouty arthritis, the bone ends fuse and immobilize the joint  Treatment: drugs, plenty of water, avoidance of alcohol

Aging  Joint Immobilization  Reduces flow of synovial fluid  Can cause arthritis symptoms  Treated by continuous passive motion (therapy)  Bones and Aging  Bone mass decreases  Bones weaken  Increases risk of hip fracture, hip dislocation, or pelvic fracture

Joints (Arthroplasty)  Arthroplasty  Joints may be replaced surgically with artificial joints  Most commonly replaced are the hips, knees, and shoulders  Hip Replacements  Partial hip replacements involve only the femur  Total hip replacements involve both the acetabulum and head of the femur  Knee Replacements  Actually a resurfacing of cartilage and may be partial or total  Potential complications of arthroplasty include infection, blood clots, loosening or dislocation of the replacement components, and nerve injury

Joints (Arthroplasty)

Osteoarthritis (OA)  Common, irreversible, degenerative (“wear-and-tear”) arthritis  85% of all Americans develop OA, more women than men  Probably related to the normal aging process

Osteoarthritis (OA)  More cartilage is destroyed than replaced in badly aligned or overworked joints  Exposed bone ends thicken, enlarge, form bone spurs, and restrict movement  Treatment: moderate activity, mild pain relievers, capsaicin creams, glucosamine and chondroitin sulfate

Lyme Disease  Caused by bacteria transmitted by the bites of ticks  Symptoms: skin rash, flu-like symptoms, and foggy thinking  May lead to joint pain and arthritis  Treatment: antibiotics

Integration with Other Systems  Bone Recycling  Living bones maintain equilibrium between  Bone building (osteoblasts)  And breakdown (osteoclasts)  Factors Affecting Bone Strength  Age  Physical stress  Hormone levels  Calcium and phosphorus uptake and excretion  Genetic and environmental factors

Integration with Other Systems  Bones Support Body Systems  The skeletal system  Supports and protects other systems  Stores fat, calcium, and phosphorus  Manufactures cells for immune system  Disorders in other body systems can cause  Bone tumors  Osteoporosis  Arthritis  Rickets (vitamin D deficiency)

Integration with Other Systems Figure 9–13 Functional Relationships between the Skeletal System and Other Systems.

Integration with Other Systems Figure 9–13 Functional Relationships between the Skeletal System and Other Systems.