Chapter 8

Arthritis

-all rheumatic diseases that affect synovial joints -always involves damage to the articular cartilage -causes vary -three types: osteoarthritis, rheumatoid arthritis, gouty arthritis

Magnetic resonance imaging (MRI)

-allows visualization of soft tissue outside the joint cavity not visible with arthroscope -cost-effective -noninvasive

Hip joint reinforcing ligaments: ligamentum teres

-also called ligament of the femoral head -originates along the transverse acetabular ligament -attaches to the fovea capitis

Osteoarthritis

-also known as degenerative arthritis or degenerative joint disease (DJD) -most common form of arthritis -generally affects individuals age 60 or older: in the United States, affects 25% of women and 15% of men over age 60 -caused by: cumulative effects of wear and tear on joints; genetic factors affecting collagen formation

Cartilaginous: Symphysis (structural classification of joints)

-amphiarthrotic joint where articulating bones separated by pad of fibrocartilage -example: joint between the two pubic bones

Fibrous: Syndesmosis (structural classification of joints)

-amphiarthrotic joint with bones connected by a ligament -example: distal joint between tibia and fibula

Glenohumoral joint features

-articular capsule: permits extensive range of motion -small articular cartilage -glenoid labrum: fibrocartilage rim; increases area of the glenoid cavity

Bone changes with aging: Osteoporosis

-bone loss sufficient to affect normal function -loss of bone mass, along with reduced cushioning of intervertebral discs, leads to increasing incidence of vertebral fractures in elderly

Building disc (IVDD)

-caused by weakened posterior longitudinal ligaments -allows compression of nucleus pulpous and distortion of annulus fibrosus -tough, outer layer of cartilage bulges laterally

Functions of synovial fluid: Nutrient distribution

-circulates continuously, providing nutrients and carrying away wastes -compression and expansion of articular cartilage assists in circulation

Components of a synovial joint: synovial fluid

-clear, straw-colored, viscous fluid -consistency of raw egg white: viscosity dye to high concentration of hyaluronic acid produced by the synovial membrane -circulates from areolar tissue into joint cavity -percolates through articular cartilage --provides oxygen and nutrients to chondrocytes --carries away metabolic wastes

Elbow joint

-complex hinge joint involving humerus, radius, and ulna -extremely stable because: 1. the bony surfaces of the humerus and ulna interlock 2. a single, thick articular capsule surrounds both the humero-ulnar and proximal radio-ulnar joints 3. strong ligaments reinforce the articular capsule -proximal radio-ulnar joint is not part of the elbow joint: capsule and ligaments help hold the humerus, ulna, and radius in position

Primary vertebral ligaments: Supraspinous ligament

-connects tips of spinous processes from the sacrum to C7 -ligamentum nuchae extends from C7 to base of the skull

Components of a synovial joint: Articular Cartilage

-covers bones at joint -structure resembles hyaline cartilage but with no perichondrium: matrix contains more water than other cartilages

Synovial (structural classification of joints)

-diarthrotic joints -permit wider range of motion than any other joint type -located at the ends of long bones

Pronation

-distal epiphysis of radius rolls across the anterior surface of the ulna -turns the wrist and hand from palm facing back (posteriorly)

Joints of the appendicular skeleton

-extensive range of motion -often weaker than axial skeleton joints examples -sternoclavicular joint: articulation between the axial skeleton and pectoral girdle and upper limb -sacro-iliac joint: attaches the sacrum of axial skeleton to the pelvic girdle

Diarthrosis (functional classification of joints)

-freely movable

Joints categorization

-functionally by amount of motion allowed, or range of motion (ROM) -structurally by anatomical organization

Shoulder joint, or glenuhumoral joint

-greatest range of motion of any joint -most frequently dislocated joint: demonstrates how stability is sacrificed for mobility ball-and-socket diarthrosis -articulation between the head of the humerus and the glenoid cavity of the scapula -stabilized by five major ligaments, surrounding muscles, and associated tendons -bursae help reduce friction: tendon of the biceps brachia surrounded by t a tubular bursa as it passes through the articular capsule

Bone changes with aging: Osteopenia

-inadequate ossification leading to loss of bone mass -often occurs with age, beginning between ages 30 and 40 -more severe in women that men

Humero-ulnar joint (specific joint of the elbow)

-largest and strongest articulation -works like a door hinge, where trochlea of humerus articulates with the trochlear notch of the ulna: shape of the trochlear notch determines the plane of movement; shapes of the olecranon fossa and olecranon limit the degree of extension

General types of movement: Gliding

-linear motion -permits sliding motion in any direction on a relatively flat surface

Components of a synovial joint: Synovial membrane

-lines the interior of the joint capsule -secretes synovial fluid into the joint cavity: fluid lubricates, cushions, prevents abrasion, and supports chondrocytes; total quantity of synovial fluid usually less than 3 mL

Amphiarthrosis (functional classification of joints)

-little movement allowed (more than synarthrosis) -much stronger than diarthrosis -articulating bones connected by collagen fibers or cartilage

Accessory structures supporting the knee: Fat pads

-localized masses of adipose tissue covered by a layer of synovial membrane -usually superficial to joint capsule -protect articular cartilage -fill in spaces created as joint moves and joint cavity changes shape

Joints, or articulations

-locations where two or more bones meet -only points at which movements of bones can occur -joints allow mobility while preserving bone strength -amount of movement allowed is determined by anatomical structure

Artificial joints

-may be method of last resort for arthritis treatment if other methods fail to slow disease progression: other methods include regular exercise, physical therapy, anti-inflammatory drugs -can restore mobility and relieve pain -high-impact activities are restricted after replacement -new joints (hip/knees) can last more than 15 years

General types of movement: Angular motion

-movement along two axes in one plane -also involves a change in angle

General types of movement Rotation

-movement around the longitudinal axis -bone end remains fixed, and the shaft rotates

Dislocation, or luxation

-movement beyond the normal range of motion -articulating surfaces forced out of position -damages joint structures -pain is from nerves monitoring capsule and surrounding tissue: no pain receptors inside a joint

Opposition (special movement)

-movement of the thumb toward the surface of the pam or pads of other fingers -enables grasping objects

Arthroscope

-narrow, flexible fiberoptic tube with tiny camera -allows exploration of a joint without major surgery -may be used in combination with other flexible instruments inserted through additional incisions to conduct surgery: called arthroscopic surgery

Synarthrosis (functional classification of joints)

-no movement allowed -extremely strong

Herniated disc (IVDD)

-nucleus pulpous breaks through annulus fibrosus and protrude into the vertebral canal -compresses spinal nerves

Supination

-opposing movement -palm is turned anteriorly

Accessory structures supporting the knee: Meniscus, or articular disc

-pad of fibrocartilage between opposing bones in a synovial joint -may subdivide a synovial cavity -may channel synovial fluid flow -allow variations in the shapes of articular surfaces

Knee joint supporting structures: Medial and lateral menisci

-pair of fibrocartilage pads -located between femoral and tibial surfaces -act as cushions and provide lateral stability

Lateral flexion

-refers to bending the vertebral column to the side -most pronounced in cervical and thoracic regions

Articular cartilage damaged by osteoarthritis

-rough, bristly collagen fibers on the surface -increases friction at the joint: promotes further degeneration

Components of a synovial joint: Joint capsule, or articular capsule

-sac enclosing the articular ends of the bones in a joint -reinforced with accessory structures (tendons, ligaments) -continuous with the periosteum of each bone: adds strength and mobility to the joint

Accessory structures supporting the knee: Bursa

-small, thin, fluid-filled with synovial fluid and lined by synovial membrane -forms in connective tissue outside a joint capsule -reduces friction -acts as shock absorber

Normal articular cartilage

-smooth, slick surface -thick cartilage with homogenous matrix

intervetebral discs components: Nucleus pulposus

-soft, elastic, gelatinous core -gives, disc resilience and shock absorption ability

Circumduction

-special term describing a complex angular movement -proximal end of bone remains fixed while distal end moves in a path that corresponds to drawing a circle

Rotation forearm

-special terms for the rotation of the forearm -movement occurs at the proximal joint between radius and ulna -radial head rotates -pronation and supination

Joints of the axial skeleton

-strong joints -permit very little movement examples -Atlanto-occipital joint articulation between the occipital bone and atlas -Atlanto-axial joint: articulation between C1 and C2

Hip Joint

-sturdy ball-and-socket diarthrosis joint: permits flexion, extension, adduction, abduction, circumduction, and rotation -articulation between the head of the femur and the acetabulum (deep fossa) of the hip bone -articular capsule of the hip -extends from the lateral and infer surfaces of the pelvic girdle to the intertrochanteric line and intertrochanteric crest of femur -encloses both head and neck of the femur -reinforced by five ligaments

Accessory ligaments

-support, strengthen, and reinforce synovial joints -capsular ligaments, or intrinsic ligaments: localized thickenings of the joint capsule

Fibrous: Gomphosis (structural classification of joints)

-synarthrotic joint binding teeth to bony sockets in maxillae and mandible

Fibrous: Suture (structural classification of joints)

-synarthrotic joint connected by dense fibrous connective tissue -located between bones of the skull

Cartilaginous: Synchondrosis (structural classification of joints)

-synarthrotic joint formed by a rigid, cartilaginous bridge between two articulating bones -example: between ends of the first pairs of ribs and the sternum

Bony: Synostosis (structural classification of joints)

-synarthrotic, totally rigid, immovable joint -formed when bones fuse -example: frontal suture and epiphyseal lines

Intervertebral discs components: Anulus fibrosus

-touch outer ring of fibrocartilage -collagen fibers attach to adjacent vertebrae

Functions of synovial fluid: Lubrication

-under compression, fluid squeezes out of the cartilage and into space between bones

Functions of synovial fluid: Shock absorption

-viscosity increases with increasing pressure

Knee joint supporting structures: Anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL)

ACL: -at full extension, slight lateral rotation of tibia tightens ACL and forces lateral meniscus between tibia and femur -this "locks" knee in extended position -opposite motion is required to "unlock"

Glenohumoral joint stabilizing ligaments

Coracoclavicular ligaments Acromioclavicular ligament Coraco-acromial ligament Coracohumeral ligament Glenohumeral ligaments

Mobility in joints

Greater range of motion results in weaker joint -synarthroses are strongest joints and have no movement -diarthroses are the most mobile joints and the weakest

Movement described by number of axes

Monoaxial: around one axis Biaxial: around two axes Triaxial: around three axes

Elbow joint reinforcing ligaments: Annular ligament

binds the head of the radius to the ulna

Humeroradial joint (specific joints of the elbow)

capitulum of humerus articulates with head of radius

Primary vertebral ligaments: Anterior longitudinal ligament

connects anterior surfaces of adjacent vertebral bodies

Primary vertebral ligaments: Ligamentum flavum

connects laminae of adjacent vertebrae

Primary vertebral ligaments: Posterior longitudinal ligament

connects posterior surfaces of adjacent vertebral bodies

Primary vertebral ligaments: Interspinous ligament

connects spinous processes of adjacent vertebrae

Knee Joint

contains three separate articulations: -two between the femur and tibia: medial condyle of tibia to medial condyle of femur; lateral condyle of tibia to lateral condyle of femur -one between the patella and patellar surface of the femur these articulations permit flexion, extension, and very limited rotation fibula is not part of the knee joint

Knee joint supporting structures: quadriceps tendon

continues as patellar ligament to anterior tibial surface

Hip joint reinforcing ligaments: Transverse acetabular ligament

crosses the acetabular notch, filling gap in the inferior border of the acetabulum

Flexion

decreases the angle of the joint

Hyperextension

extension past the anatomical position

Lateral rotation (referring to limbs)

external, or outward rotation anterior surface of a limb turns away from the long axis of the trunk

Syndesmoses of vertebral column

fibrous joints, including vertebral ligaments

Rheumatism

general term indicating pain and stiffness in the bones and/or muscles

Extension

increases the angle of the joint

Medial rotation (referring to limbs)

internal, or inward rotation anterior surface of a limb turns toward the long axis of the trunk

Synchondroses of vertebral column

intervertebral joints, forming intervertebral discs -account for about 1/4 length of the vertebral column -with increasing age, water content decreases --loss of cushioning ability increases risk of vertebral injury --vertebral column shortens

Vertebral synovial joints

joints between bony processes

Abduction

movement away from the longitudinal axis in the frontal plane

Plantar flexion (movement of the foot)

movement extending the ankle as in standing on tiptoe

Adduction

movements toward the longitudinal axis in the frontal plane

Depression (special movements)

moving a body part inferiorly (as in opening your jaw)

Circumduction (movement with reference to anatomical position)

moving a body part such that the distal end traces a circle while the proximal end stays in one position

Elevation (special movements)

moving a body part superiorly (as in closing your jaw)

Protraction (special movement)

moving a part of the body anteriorly in the horizontal plane

Elbow joint muscle attachments

muscles that extend the elbow attach on the olecranon on the posterior surface -controlled by the radial nerve tendon of the biceps brachia attaches at the radial tuberosity -contraction produces supination of forearm and flexion at the elbow severe stresses can still produce dislocation or other injuries, especially when epiphyseal growth is not complete

Eversion (special movement; movement of the foot)

opposing motion turning the sole outward

Nursemaid's Elbow

partial dislocation of the radial head from annular ligament

Accessory structures supporting the knee

provide support and additional stability tendon of the quadriceps muscle -not part of knee joint itself -limits range of motion and provides mechanical support

Knee joint supporting structures: fibular collateral ligament, or lateral collateral ligament (LCL)

provides lateral support

Knee joint supporting structures: Tibial collateral ligament, or medial collateral ligament (MCL)

provides medial support

Flexion and extension

refer to movements at hinge joints of the long bones of the limbs

Abduction and adduction

refers to the movements of the appendicular skeleton

Retraction

reverse of protraction; returning the body part to normal position

Knee joint supporting structures: Popliteal ligaments

run between femur and heads of the tibia and fibula

Accessory ligaments: Extrinsic ligaments

separate from the joint capsule -extracapsular ligaments: pass outside the joint capsule -example: patellar ligament -intracapsular ligaments: pass inside the joint capsule -example: crucial ligaments

Elbow joint reinforcing ligaments: Radial collateral ligament

stabilizes the lateral surface of the elbow joint

Elbow joint reinforcing ligaments: Ulnar collateral ligament

stabilizes the medial surface of the elbow joint

Inversion (special movement; movement of the foot)

twisting motion turning the sole inward

Dorsiflexion (movement of the foot)

upward movement of the foot or toes

Rotation

when referring to the trunk, described as left and right rotation: described in reference to anatomical position