Joints & Joint Movements Human Anatomy Sonya Schuh-Huerta, Ph.D.

1. Joints & Joint Movements Human Anatomy Sonya Schuh-Huerta, Ph.D.

2. Joints • Rigid elements of the skeleton meet at joints or articulations • Greek root “arthro” means joint • Structure of joints • Enables resistance to crushing, tearing, & other forces

3. Classifications of Joints • Joints can be classified by function or structure • Functional classification based on amount of movement • Synarthroses immovable; common in axial skeleton • Amphiarthroses slightly movable; common in axial skeleton • Diarthroses freely movable; common in appendicular skeleton (all synovial joints)

4. Classifications of Joints • Structural classification based on • Material that binds bones together • Presence or absence of a joint cavity • Structural classifications include: • Fibrous • Cartilaginous • Synovial

5. Classifications of Joints

6. Sutures – A Type of Fibrous Joint • Bones are tightly bound by a minimal amount of fibrous tissue • Only occur between the bones of the skull • Allow bone growth so the skull can expand with brain during childhood • Fibrous tissue ossifies in middle age • Synostoses = closed sutures

7. Syndesmoses – A Type of Fibrous Joint • Bones are connected exclusively by ligaments • Amount of movement depends on length of fibers • Tibiofibular joint = immovable synarthrosis • Interosseous membrane between radius & ulna = freely movable diarthrosis

8. Gomphoses – A Type of Fibrous Joint • Tooth in a socket • Connecting ligament  the periodontal ligament

9. Fibrous Joints (a) Suture (b) Syndesmosis (c) Gomphosis Joint held together with very short, interconnecting fibers, and bone edges interlock. Found only in the skull. Joint held together by a ligament. Fibrous tissue can vary in length but is longer than in sutures. Peg-in-socket fibrous joint. Periodontal ligament holds tooth in socket. Socket of alveolar process Fibula Suture line Tibia Root of tooth Dense fibrous connective tissue Ligament Periodontal ligament

10. Cartilaginous Joints • Bones are united by cartilage • Lack a joint cavity • 2 types • Synchondroses • Symphyses

11. Synchondroses • Hyaline cartilage unites bones • Epiphyseal plates • Joint between first rib & manubrium (a) Synchondroses Bones united by hyaline cartilage Sternum (manubrium) Epiphyseal plate (temporary hyaline cartilage joint) Joint between first rib and sternum (immovable)

12. Symphyses • Fibrocartilage unites bones; resists tension & compression • Slightly movable joints that provide strength with flexibility • Intervertebral discs • Pubic symphysis • Hyaline cartilage present as articular cartilage

13. Symphyses (b) Symphyses Bones united by fibrocartilage Body of vertebra Fibrocartilaginous intervertebral disc Hyaline cartilage Pubic symphysis

14. Synovial Joints • Most movable type of joint!!! • All are diarthroses  what does that mean? • Each contains a fluid-filled joint cavity

15. General Structure of Synovial Joints • Articular cartilage • Ends of opposing bones are covered with hyaline cartilage • Absorbs compression • Joint cavity (= synovial cavity) • Unique to synovial joints • Cavity is a potential space that holds a small amount of synovial fluid

16. General Structure of Synovial Joints • Articular capsule joint cavity is enclosed in a 2-layered capsule • Fibrous capsule dense irregular connective tissue, which strengthens joint • Synovial membrane loose connective tissue • Lines joint capsule & covers internal joint surfaces • Makes synovial fluid

17. General Structure of Synovial Joints • Synovial fluid • A viscous fluid similar to raw egg white • A filtrate of blood • Arises from capillaries in synovial membrane • Contains glycoprotein molecules secreted by fibroblasts

18. General Structure of Synovial Joints • Reinforcing ligaments • Often are thickened parts of the fibrous capsule • Sometimes are extracapsular ligaments located outside the capsule • Sometimes are intracapsular ligaments located internal to the capsule

19. General Structure of Synovial Joints Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Articular capsule Synovial membrane Periosteum (a) A typical synovial joint

20. General Structure of Synovial Joints • Richly supplied with sensory nerves • Detect pain • Most monitor how much the capsule is being stretched

21. General Structure of Synovial Joints • Have a rich blood supply • Most supply the synovial membrane • Extensive capillary beds produce basis of synovial fluid • Branches of several major nerves & blood vessels

22. Synovial Joints with Articular Discs • Some synovial joints contain an articular disc • Temporomandibular joint & Knee joint • Occur in joints whose articulating bones have somewhat different shapes

23. How Synovial Joints Function • Synovial joints  lubricating devices • Friction could overheat & destroy joint tissue & bone ends • Are subjected to compressive forces • Fluid is squeezed out as opposing cartilages touch • Cartilages ride on the slippery film

24. Bursae & Tendon Sheaths • Bursae & tendon sheaths are not synovial joints • Closed bags of lubricant • Reduce friction between body elements • Bursa = a flattened fibrous sac lined by a synovial membrane • Tendon sheath = an elongated bursa that wraps around a tendon

25. Bursae & Tendon Sheaths Coracoacromial ligament Acromion of scapula Subacromial bursa Coracoacromial ligament Joint cavity containing synovial fluid Subacromial bursa Cavity in bursa containing synovial fluid Fibrous articular capsule Humerus resting Hyaline cartilage Bursa rolls and lessens friction. Tendon sheath Synovial membrane Tendon of long head of biceps brachii muscle Fibrous capsule Humerus head rolls medially as arm abducts. Humerus Humerus moving (a) Frontal section through the right shoulder joint (b) Enlargement of (a), showing how a bursa eliminates friction where a ligament (or other structure) would rub against a bone

26. Movements Allowed by Synovial Joints • 3 basic types of movement • Gliding one bone across the surface of another • Angular movement movements change the angle between bones • Rotation movement around a bone's long axis

27. Gliding (a) Gliding movements at the wrist Gliding Joints • Flat surfaces of two bones slip across each other • Gliding occurs between: • Carpals • Articular processes of vertebrae • Tarsals

28. Angular Movements • Increase or decrease angle between bones • Movements involve: • Flexion & extension • Abduction & adduction • Circumduction

29. Angular Movements Extension Flexion (b) Angular movements: flexion & extension of the neck

30. Angular Movements Extension Flexion (c) Angular movements: flexion & extension of the trunk

31. Angular Movements Flexion Extension Flexion Extension (d) Angular movements: flexion & extension at the shoulder and knee

32. Angular Movements Abduction Circumduction Adduction (e) Angular movements: abduction, adduction, & circumduction of the upper limb at the shoulder

33. Movement of theglenohumoral joint PLAY

34. Rotation • Involves turning movement of a bone around its long axis • The only movement allowed between atlas & axis vertebrae • Occurs at the neck, shoulder, elbow, hip

35. Rotation Rotation Lateral rotation Medial rotation (f) Rotation of the head, neck, & lower limb

36. Special Movements • Elevation lifting a body part superiorly • Depression moving the elevated part inferiorly Elevation of mandible Depression of mandible Elevation Depression

37. Special Movements • Protraction nonangular movement anteriorly • Retraction nonangular movement posteriorly Protraction of mandible Retraction of mandible Protraction Moving a body part in the anterior direction Retraction Moving a body part in the posterior direction

38. Special Movements • Supination forearm rotates laterally, palm faces anteriorly • Pronation forearm rotates medially, palm faces posteriorly • Brings radius across the ulna

39. Special Movements Pronation (radius rotates over ulna) Supination (radius and ulna are parallel) Pronation (P) Rotating the forearm so the palm faces posteriorly Supination (S) Rotating the forearm so the palm faces anteriorly

40. Special Movements • Opposition thumb moves across the palm to touch the tips of other fingers Opposition

41. Special Movements • Inversion & eversion • Special movements at the foot • Inversion  turns sole medially • Eversion  turns sole laterally

42. Special Movements Inversion Eversion Inversion Turning the sole of the foot medially Eversion Turning the sole of the foot laterally

43. Special Movements • Dorsiflexion&plantarflexion • Up-and-down movements of the foot • Dorsiflexion  lifting the foot so its superior surface approaches the shin • Plantar flexion  depressing the foot, elevating the heel (ballet toe point)

44. Special Movements Dorsiflexion Plantar flexion Dorsiflexion Lifting the foot so its superior surface approaches the shin Plantar flexion Depressing the foot elevating the heel

45. Eversion of Ankle joint (5a) PLAY

46. Synovial Joints Classified by Shape • Plane joint • Articular surfaces are flat planes • Short gliding movements are allowed • Intertarsal & intercarpal joints • Movements are nonaxial • Gliding does not involve rotation around any axis

47. Plane Joint Nonaxial movement Metacarpals Carpals Gliding (a) Plane joint

48. Synovial Joints Classified by Shape • Hinge joints • Cylindrical end of one bone fits into a trough on another bone • Angular movement is allowed in one plane • Elbow, ankle, & joints between phalanges • Movement is uniaxial allows movement around one axis only

49. Hinge Joint Uniaxial movement Humerus Medial/ lateral axis Ulna Flexion & extension (b) Hinge joint

50. Synovial Joints Classified by Shape • Pivot joints • Classified as uniaxial – rotating bone only turns around its long axis • Examples • Proximal radioulnar joint • Joint between atlas & axis