Chapter 8

Joints or Articulations

Why do we need them?

• Articulations are junctions between bones• They 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

contraction

8-2

Classification of Joints-Structural and Functional

• Fibrous Joints-lack a synovial cavity and permit little to no movement• dense connective tissues connect

bones• between bones in close contact

• Cartilaginous Joints-lack a synovial cavity and allow little or no movement• hyaline cartilage or fibrocartilage

connect bones form a tight connection

• Synovial Joints-have a joint cavity• most complex• allow free movement

• synarthrotic• immovable

• amphiarthrotic• slightly movable

• diarthrotic• freely movable

8-3

Fibrous Joints

3 Types• Syndesmosis• Suture• Gomphosis

Syndesmosis• long fibers connect

bones• amphiarthrotic• distal ends of tibia

and fibula

8-4

Fibrous Joints

Suture• between flat bones (skull)• synarthrotic• thin layer of connective

tissue connects bones• Metopic suture of frontal

bone usually fuses completely

Gomphosis• cone-shaped bony

process in a socket• tooth in jawbone• synarthrotic

8-5

Cartilaginous Joints

2 Types• Synchondrosis• Symphysis

Synchondrosis• bands of hyaline cartilage

unite bones• epiphyseal plate

(temporary)• between manubrium and

first rib• synarthrotic (immoveable)

8-6

Cartilaginous Joints

Symphysis• pad of fibrocartilage between bones• pubis symphysis• joint between bodies of vertebrae• amphiarthrotic

8-7

Synovial Joints

• diarthrotic• joint cavity allows joint to move freely• synovial fluid-reduce friction, absorb shocks, supply oxygen and remove waste from chondrocytes• joint capsule• synovial membrane-inner layer of the articular capsule• Articular cartilage covers ends• bursae-reduce friction, cushion movement

8-8

Types of Synovial Joints

Ball-and-Socket Joint• hip• shoulder• Permit multiaxial movement

Condyloid Joint• between metacarpals

and phalanges• Oval shaped projection

fits into oval shaped depression

8-9

Types of Synovial Joints

Gliding Joint or Planar Joints• between carpals• between tarsals• Articular surfaces are flat to slightly

curved

Hinge Joint• elbow• between phalanges

8-10

Types of Synovial Joints

Pivot Joint• between proximal

ends of radius and ulna and between axis and atlas

Saddle Joint• between carpal and

metacarpal of thumb• Modified condylar

joint

8-11

Types of Joint Movements

• abduction- movement away from midline• Adduction-movement toward midline• dorsiflexion-bend the foot at the ankle (stand on heels)• Plantarflexion-bend foot at ankle toward inferior (stand on toes)• flexion-decrease the angle• Extension-increase angle of joint• Hyperextension-continue extension beyond anatomical position

8-12

Types of Joint Movements

• rotation-bone turns on longitudial axis• Circumduction-one end remains stationary• supination –palm is up (hold soup)• pronation-palm is down or facing the rear

8-13

Types of Joint Movements• eversion-turning sole of foot laterally• inversion-turning sole medially• protraction-/retraction• elevation/depression

8-14

Shoulder Joint

• ball-and-socket• head of humerus and

glenoid cavity of scapula• loose joint capsule• 4 bursae reduce friction-

look up names……• ligaments prevent

displacement• very wide range of

movement• Rotator cuff-

supraspinatus, infraspinatus, teres minor, subscapularis, work together to join scapula to humerus

8-15

Shoulder Joint

8-16

Elbow Joint

• hinge joint• trochlea of humerus• trochlear notch of ulna

• gliding joint• capitulum of humerus• head of radius

• flexion and extension• many reinforcing ligaments• Including radial collateral ligament and ulnar collateral ligament• stable joint

8-17

Elbow Joint

8-18

Hip Joint

• ball-and-socket joint• head of femur• acetabulum• Acetabular labrum is a

fibrocartilage rim that increases depth of socket

• heavy joint capsule• many reinforcing

ligaments-like ischiofemoral and iliofemoral ligament

• less freedom of movement than shoulder joint

8-19

Hip Joint

8-20

Knee Joint

• largest joint and most complex• medial and lateral condyles of distal

end of femur• medial and lateral condyles of

proximal end of tibia• femur articulates anteriorly with

patella• modified hinge joint• flexion/extension/little rotation• strengthened by many ligaments and

tendons-PCL, ACL, tibial collateral ligament, fibular collateral ligament,

• menisci separate femur and tibia• bursae include pre-patellar bursae

which is often damaged when you bump the anterior knee 8-21

Knee Joint

8-22

Life-Span Changes

• Joint stiffness is an early sign of aging• Regular exercise can prevent stiffness• Fibrous joints first to strengthen over a

lifetime• Changes in symphysis joints of vertebral

column diminish flexibility and decrease height

• Synovial joints lose elasticity

8-23

Clinical Application

Joint DisordersSprains

• damage to cartilage, ligaments, or tendons associated with joints

• forceful twisting of joint

Bursitis• inflammation of a bursa• overuse of a joint

Arthritis• inflamed, swollen, painful joints

• Rheumatoid Arthritis-RA, autoimmune disease• Osteoarthritis or OA-most common, wear and tear• Gout-often strikes big toe, peanuts can aggravate this 8-24

Disorders

• Cartilage injury-usually require surgery• Dislocation (luxation)-forced bone out of

alignment, usually downward displacement• Partial dislocation is subluxation• Bursitis-also known as: housemaids knee,

tennis elbow, student elbow (olecranon bursitis)• Tendonitis-inflammation of tendon sheath, same

type symptoms as bursitis