UNIT 3 : Joints CH 9

location, function, structure of joints

What are the functions of joints?

1. synarthrosis - immovable

• skull sutures, epiphyseal plate

2. amphiarthrosis - slightly movable

• distal tibia-fibula, pubic symphysis, b/w vertebral bodies

3. diarthrosis - freely movable

• knee, shoulder, hip

what are the three types of structural joints?

1. fibrous

2. cartilaginous

3. synovial

what are fibrous joints?

1. no synovial cavity

2. held together by bfibrous CT

3. slight or no movement

EX : skull sutures

What are cartilage joints?

1. no synovial cavity

2. connected by cartilage

3. slight or no movement (amphiarthrosis)

EX : epiphyseal plate → no movement

EX : pubic symphysis → slight movement

what are synovial joints?

1. freely moveable

2. synovial cavity seperates articulating bones

EX : knees, elbows, hipsw

What are the parts of the synovial joint?

1. synovial cavity

• hyaline

• covers ends of bone

• reduces friction, absorbs shock

2. joint (articular) capsule

• dense, irregular CT

• The outer layer attaches to the peristeum

• thickenings in fibrous capsule called ligaments (bind bone to bone)

3. synovial membrane

• inner lining of fibrous capsule

• areolar CT and synoviocytes → secretes synovial fluid

• brings nutrients to articular cartilage

• has phagocytic cells

what is a mensci in a synovial joint?

1. fibrocartilage pads

2. attached around edges to the capsule

3. allow 2 bones of different shapes to fit more tightly → increase stability

What is a bursa?

A sac-like structure between 2 other structures

1. skin/bone or tendon/bone or ligament/bone

2. acts as a cushion

3. bursitiswh

what is a tendon sheath?

1. tube-like bursa wrapping around tendon

2. reduces friction

3. found where many tendons are in a confined space

4. can become inflamed or infected

what are the types of synovial joints?

1. planar - flat bone ends/surface

2. hinge - convex surface + concave surface

3. pivot - round surface + ring (bone + ligament)

4. condyloid (ellipsoidal) - oval shaped condyle + elliptical cavity

5. saddle - one bone saddled-shaped; other bone fits as a person would sitting in that saddle

6. ball and socket - ball fitting into a cuplike depression

What are the axes of movement?

1. monaxial/monoaxial/uniaxial - movement on only 1 axis

2. biaxial - movement on 2 axes

3. triaxial/multi-axial - movenemntg on 3 axeswh

What is an angular movement?

increases or decreases in angle

1. flexion or extension

2. adduction or abduction (ball and socket, condyloid joints)

what is a rotation movement?

The bone revolves around its own axis (longitudinal)

1. internal/medial rotation

2. external/lateral rotation

Ball and socket and pivot type joints

what is a plantar joint? (synovial joint)

1. Bone surfaces are flat

2. side-to-side gliding movement

3. rotation prevented by ligaments

4. limited monoaxial

EX : intercarpal or intertarsal joints

EX : sternoclavicular joint

EX : vertebrocostal joints

What is a hinge joint? (synovial joint)

1. convex surface of one bones fits onto concave surface of 2nd bone

2. monoaxial (like door hinge)

EX : knee, elbow, interphalangeal joints

Movements produced

• flexion

• extension

• hyperextension

What is a pivot joint? (synovial joint)

1. rounded surface of bone articulates with ring formed by the 2nd bone and a ligament

2. monoaxial

• only internal and external rotation

EX : proximal radioulnar joint (supination and pronation)

Atlanto-axial joint

• turning head side to side (no movement)

What is a condyloid or Ellipsoidal joint? (synovial joint)

1. oval-shaped projection fits into oval (elliptical) depression

2. biaxial - flexion and extension, and adduction and abduction

EX : wrist and metacarpophalangeal joints for digits 2 to 5

What is a saddle joint? (synovial joint)

1. one one saddled-shaped; other bone fits as a person would sitting in that saddle

2. biaxial

• circumduction allows tip of thimb travel in circle

• opposition allows tip of thumb to touch tip of other fingers

EX : trapezium (a carpal bone) and metacarpal of the thumb

what is a ball and socket joint? (synovial joint)

1. ball fitting into a suplike depressiom

2. tri-axial

• flexion and extension

• abduction and adduction

• rotation

EX : shoulder joint, hip joint

what is Rheumatoid Arthritis?

audoimmune disorder (body attacks itself)

cartilage attacked

inflammation, swelliung and pain

final step is fusion of joint

What is osteoarthritis?

degenerative joint disease

• aging, wear and tear

deterioration of cartilage produces bone spurs

• restrict movement

pain upon awakening - gets better with movement