3. An Introduction to 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

4. 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
Bony, fibrous, cartilaginous or synovial

5. Classification of Joints
Functional Classifications
Synarthrosis (immovable joint) (e.g., skull suture)
No movement
Bones united by fibrous or cartilaginous connective tissues
May fuse over time
Amphiarthrosis (slightly movable joint) (e.g., b/n tibia and fibula)
Little movement
Fibrous or cartilaginous connections
Diarthrosis (freely movable joint)
More movement
Also called synovial joints
Subdivided by type of motion
Syn-ar-thro-seas
Amphi-throw-sis
Die-arth-throw-sis

6. Classification of Joints
Functional Classifications
Synarthroses (immovable joints)
Are very strong
Edges of bones may touch or interlock
Four types of synarthrotic joints:
Suture (Fibrous joint - e.g., b/n bones of the skull)
Gomphosis (Fibrous joint - e.g., b/n the teeth and jaws)
Synchondrosis (Cartilaginous joint - e.g., ephiphyseal cartilages)
Synostosis (Bony fusion - e.g., ephiphyseal lines)
Synarthrodial joints are those lacking a joint cavity, so they are not freely moveable.
Instead the bones are united by cartilage or fibrous tissue.
An immovable joint is called a synarthrosis.
What’s a slightly moveable joint called? Amphiarthrosis.
What about a freely movable joint? Diarthrosis.
A suture is an example of an? synarthrosis.
The synarthsrosis that binds the teeth to the bony sockets is a gom-pho-sis.
An epiphyseal line is an example of a? synostosis.
Know the four major types of synarthrotic joints.

7. 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

8. 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

9. Classification of Joints

10. 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

11. Classification of Joints

12. Classification of Joints
Functional Classifications
Synovial joints (diarthroses)
Also called movable joints
At ends of long bones
Within articular capsules
Lined with synovial membrane
A synovial joint is an example of? diaarthrosis.
Synovial fluid will reduce friction.
Fig 9-1

13. Synovial Joints Components of Synovial Joints Synovial fluid
Contains slippery proteoglycans secreted by fibroblasts
Functions of synovial fluid:
lubrication
nutrient distribution
shock absorption
Protecting articular cartilage

14. 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

15. Synovial Joints
Bursa = pockets of synovial fluid that cushion where tendons or ligaments rub.
They are found in tendon sheaths, beneath the skin covering a bone, within connective tissue exposed to friction or pressure, and around many synovial joints, but not around blood vessels.
Meniscus = Fibrous cartilage pad (articular disc).
The most common athletic injury produces damage to the lateral meniscus.
Tendon = attach muscles around the joint to provide support
Ligaments = support and strengthen joints. Sprain = ligaments with torn collagen fibers
Patellar ligament = provides support to the front of the knee joint.
Articular cartilage = is slick and smooth and prevents bones from touching
Arthritus always involves damage to the articular cartilage but the specific cause can vary.
Fat pad = protects articular cartilage and assist the Bursa in reducing friction b/n the patella and other tissues.
Fig 9-1

16. Synovial Joints Injuries Dislocation (luxation)
Articulating surfaces forced out of position
Damages articular cartilage, ligaments, joint capsule
Subluxation
A partial dislocation
What are the functions of synovial fluid? Shock absorption, lubrication, provide nutrients, protect articular cartilage.

17. Movements Types of Dynamic Motion Linear motion (gliding)
2 surfaces slide past each other ex., b/n carpal or tarsal bones and clavicle and manubrium
Angular motion
Flexion, Extension, Hyperextension, Circumduction
Rotation
Left, right, medial or internal, lateral or external, pronation, supination
Pronation = rotaing forearm so the radius is over the ulna.
Supination = forearm in the anatomical position.

18. Movements
Types of Dynamic Motion
Fig 9-2

19. Movements (Angular) Fig 9-3
Flexing is decreasing the angle to the axis, such as moving the hand toward the shoulder.
Extension is toward the anatomical positon.
Hyperextension is an extension beyond the anatomical position.
What is nodding your head “yes” an example of? Flexion and extension
Fig 9-3

20. Movements (Angular) Angular Motion Abduction Adduction Angular motion
Frontal plane
Moves away from longitudinal axis
Adduction
Moves toward longitudinal axis
Fig 9-3

21. Movements (Angular) Angular Motion Circumduction
Circular motion without rotation
Angular motion
What’s a movement away from the midline of the body called? Abduction.
Fig 9-3

22. Movements (Rotational)
Pronate: rotate palm down so radius is over ulna
Supinate: forearm is in the anatomical position, ulna is medial, radius is lateral
Everybody supinate – turn the palm of your hand upward.
Fig 9-4

23. Movements Types of Movements at Synovial Joints Special movements
Inversion:
twists sole of foot medially or in
Eversion:
twists sole of foot laterally or out
Dorsiflexion:
flexion at ankle (lifting toes)
Plantar flexion:
extension at ankle (pointing toes)
A common injury to the ankle occurs by excessive turning of the sole inward. What’s this called? Inversion.
Dorsiflexion and plantar flexion involve moving the foot.
Kicking a stone with the tip of your foot would be an example of dorsiflexion.
Plantar flexion is the foot movement that allows a ballerina to stand on her toes.

24. 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)

25. Movements Special Movements at Synovial Joints Elevation Depression
Moves in superior direction (up)
Depression
Moves in inferior direction (down)
Lateral flexion
Bends vertebral column from side to side
A good example of depression is simply opening the mouth.

26. Movements
Fig 9-5

27. Movements Classification of Synovial Joints by Shape
Gliding – intercarpal articulations/ joints b/n vertebrae
Hinge – ankle, knee, elbow, b/n phalanges
Pivot – C1 and C2 (atlas and axis)/ radio-ulnar joint
Ellipsoid –joints b/n fingers and metacarpal bones/radio-carpal joint
Saddle – straddled joint like the 1st carpometacarpal joint b/n the thumb and underlying trapezium (carpal bone)
Ball-and-socket – shoulder and hip joints
The intercarpal articulations are gliding joints.
The joints b/n vertebrae are also examples of gliding joints.
The ankle is an example of a hinge joint.
The joint type between my phalanges is also a hinge joint.
The joints that connect the 4 fingers with the metacarpal bones are ellipsoid joints.
The radiocarpal joint is also an example of an ellipsoid joint.

28. Movements Fig 9-6 Gliding joint has limited motion
Hinge joint has angular motion in a single plane
Pivit joint rotates.
Fig 9-6

29. Movements Ellipsoid Joints Saddle Joints Ball-and-Socket 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)
An example of an ellipsoid joint is the radiocarpal joint.

30. Movements Fig 9-6 Ellipsoid joint has motion in 2 planes
Saddle joint has straddled joints like the joint b/n the trapezium and the metacarpal bone of the thumb.
Ball-and-socket joint has a round articular face in a depression
Fig 9-6

31. Diarthrodial Joints Type of Joint Movement Example
Hinge Flexion/extension Elbow, Knee
Pivot Rotation Atlas/axis
Ball and socket Flexion/extension Shoulder, Hip
Abduction/adduction
External rotation
Internal rotation
Circumduction
Saddle Flexion/extension Thumb b/n carpals Abduction/adduction and metatarsals
Ellipsoidal Flexion/extension Wrist
Abduction/adduction Ankle

32. 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

33. Intervertebral Articulations
Intervertebral disc = pads of fibrous cartilage separating vertebral bodies
Anulus fibrosus = tough outer layer attaches disc to vertebrae
Nucleus pulposus = elastic, gelatinous core that absorbs shock
Curling into the fetal position does what to the intervertebral joints? Flexes them.
Fig 9-7

34. 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

35. Intervertebral Articulations
Six Intervertebral Ligaments
Anterior longitudinal ligament
Connects anterior bodies
Posterior longitudinal ligament
Connects posterior bodies
Ligamentum flavum
Connects laminae
Interspinous ligament
Connects spinous processes
Supraspinous ligament
Connects tips of spinous processes (C7 to sacrum)
Ligamentum nuchae
Continues supraspinous ligament (C7 to skull)

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

37. 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

38. Intervertebral Articulations
A herniated disc is caused by a protrusion of the nucleus pulposus.
Herniated disc is caused by a protrusion of the nucleus pulposus.
Fig 9-8

39. 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 (freely moveable joint)
Between head of humerus and glenoid cavity of scapula

40. 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

41. The Shoulder Joint Shoulder Ligaments Shoulder Separation Glenohumeral
Coracohumeral
Coraco-acromial
Coracoclavicular
Acromioclavicular
Shoulder Separation
Dislocation of the shoulder joint
Which one of those ligaments do you think connects the clavicle and the acromion of the scapulae? Acromioclavicular.

42. The Shoulder Joint Shoulder Muscles (also called rotator cuff)
Supraspinatus
Infraspinatus
Subscapularis
Teres minor
Shoulder Bursae
Subacromial
Subcoracoid
Subdeltoid
Subscapular
The rotator cuff consists of 4 tendons of 4 muscles that stabilize the shoulder joint.
It functions to reinforce the joint capsule and limit the range of movements.
You can imagine a white-water rafter or a baseball pitcher might have a great risk of developing a rotator cuff injury.
SITS is a useful mnemonic.

43. The Shoulder Joint Fig 9-9
Acromion = point of articulation with clavicle stabilizing the joint by projecting laterally and superior to the humerus.
Coracoid process = stabilizing the joint also by projecting laterally and superior to the humerus.
Coracoacromial ligament = shoulder ligament b/n the acromion and the coracoid process.
Glenoid labrum = fibrous cartilage lining that extends past bone to deepen the socket of the glenoid cavity.
Fig 9-9

44. The Shoulder Joint Fig 9-9
Acromion = point of articulation with clavicle stabilizing the joint by projecting laterally and superior to the humerus.
Coracoid process = stabilizing the joint also by projecting laterally and superior to the humerus.
Coracoacromial ligament = shoulder ligament b/n the acromion and the coracoid process.
Glenoid labrum = fibrous cartilage lining that extends past bone to deepen the socket of the glenoid cavity.
Fig 9-9

45. The Elbow Joint A stable hinge joint
With articulations involving humerus, radius, and ulna
Articulations of the Elbow
Humero-ulnar joint
Largest and strongest articulation at the elbow
Trochlea of humerus and trochlear notch of ulna
Limited movement
Humeroradial joint:
Smaller articulation
Capitulum of humerus and head of radius
The elbow is a good example of a hinge joint.
It’s a monaxial joint moving in one plane.
It’s extremely stable because the ulna and the humerus interlock.

46. The Elbow Joint
Fig 9-10

47. 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
Fig 9-10

48. The Hip Joint Also called coxal joint
Strong ball-and-socket diarthrosis
Wide range of motion
Factors that increase stability:
Strong muscular padding
Tough capsule
Almost complete bony socket
Supporting ligaments

49. The Hip Joint Structures of the Hip Joint Ligaments 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 normal movement of the hip joint during walking involves what kind of movement? Flexion and extension.

50. The Hip Joint
Fig 9-11

51. The Hip Joint
Fig 9-11

52. 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

53. 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 most common injury to the menisci involve having the lateral surface of the leg driven medially causing a tear in the medial meniscus.
Within the knee joint, the medial and lateral menisci act as cushions and conform to the shape of the articulating surfaces.
Sometimes the meniscus can be heard and felt popping in and out of position when the knee is extended.

54. 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)
Complete dislocation of the knee is rare b/c the knee contains 7 major ligaments.
The patellar ligament provides support to the front of the knee joint.
The back of the knee joint is reinforced by popliteal ligaments.
The medial surface of the knee joint is reinforced by the tibial collarteral ligament.
And the lateral surface of the knee by the fibular collateral ligament.
The ligaments that limit the anterior-posterior movement of the femur and maintain alignment of the femoral and tibial condyles are the cruciate ligaments.

55. The Knee Joint
Fig 9-12

56. The Knee Joint
Fig 9-12

57. Aging Rheumatism Arthritis Osteoarthritis
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

58. Aging Rheumatoid Arthritis Gouty 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
A primary sign of rheumatoid arthritis is swelling and inflammation of the synovial membrane.

59. Aging Joint Immobilization Bones and Aging
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

60. Integration with Other Systems
Factors Affecting Bone Strength
Age
Physical stress
Hormone levels
Calcium and phosphorus uptake and excretion
Genetic and environmental factors

61. Integration with Other Systems
Fig 9.13 Functional Relationships between the Skeletal System and Other Systems.
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

62. Integration with Other Systems
Fig 9.13 Functional Relationships between the Skeletal System and Other Systems.
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings