1. 1 Chapter 9 Joints

2. 2 Joints (articulations or arthrosis) hold bones together but permit movement Point of contact –between two bones –between cartilage and bone –between teeth and bones Arthrology  study of joints Kinesiology  study of motion

3. 3 Classification of Joints Structural classification is based on the presence or absence of a synovial (joint) cavity and type of connecting tissue. Structurally, joints are classified as –fibrous, cartilaginous, or synovial. Functional classification based upon movement: –immovable  synarthrosis –slightly movable  amphiarthrosis –freely movable  diarthrosis

4. 4 Fibrous Joints Lack a synovial cavity Bones held closely together by fibrous connective tissue Little or no movement (synarthroses or amphiarthroses) Three structural types –sutures –syndesmoses –gomphoses

5. 5 Sutures Thin layer of dense fibrous connective tissue unites bones of the skull Immovable (synarthrosis) If fuse completely in adults is synostosis

6. 6 Syndesmosis Fibrous joint –bones united by ligament Slightly movable (amphiarthrosis) Anterior tibiofibular joint and Interosseous membrane

7. 7 Gomphosis Ligament holds cone-shaped peg in bony socket Immovable (amphiarthrosis) Teeth in alveolar processes

8. 8 Cartilaginous Joints Lacks a synovial cavity Allows little or no movement Bones tightly connected by fibrocartilage or hyaline cartilage Two types –synchondroses –symphyses

9. 9 Synchondrosis Connecting material is hyaline cartilage Immovable (synarthrosis) Epiphyseal plate

10. 10 Symphysis Fibrocartilage is connecting material Slightly movable (amphiarthroses) Intervertebral discs and pubic symphysis

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12. 12 Articular Capsule The articular capsule surrounds a diarthrosis, encloses the synovial cavity, and unites the articulating bones. The articular capsule is composed of two layers - the outer fibrous capsule (which may contain ligaments) and the inner synovial membrane (which secretes a lubricating and joint- nourishing synovial fluid). The flexibility of the fibrous capsule permits considerable movement at a joint, whereas its great tensile strength helps prevent bones from dislocating. Other capsule features include ligaments and articular fat pads.

13. 13 Synovial Joints Synovial cavity separates articulating bones Freely moveable (diarthroses) Articular cartilage –reduces friction –absorbs shock Articular capsule –surrounds joint –thickenings in fibrous capsule called ligaments Synovial membrane –inner lining of capsule

14. 14 Special Features Synovial Membrane –secretes synovial fluid containing slippery hyaluronic acid –brings nutrients to articular cartilage Accessory ligaments –extracapsular ligaments outside joint capsule –intracapsular ligaments within capsule Articular discs or menisci –attached around edges to capsule –allow two bones of different shapes to fit tightly –increase stability of knee - torn cartilage Bursae  saclike structures between structures –skin/bone or tendon/bone or ligament/bone

15. 15 Nerve and Blood Supply Nerves to joints are branches of nerves to nearby muscles Joint capsule and ligaments contain pain fibers and sensory receptors Blood supply to the structures of a joint are branches from nearby structures –supply nutrients to all joint tissues except the articular cartilage which is supplied from the synovial fluid

16. 16 Bursae and Tendon Sheaths Bursae –fluid-filled saclike extensions of the joint capsule –reduce friction between moving structures skin rubs over bone tendon rubs over bone Tendon sheaths –tubelike bursae that wrap around tendons at wrist and ankle where many tendons come together in a confined space Bursitis –chronic inflammation of a bursa

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18. 18 TYPES OF SYNOVIAL JOINTS Planar Joint Bone surfaces are flat or slightly curved Side to side movement only nonaxial Rotation prevented by ligaments Examples –intercarpal or intertarsal joints –sternoclavicular joint –vertebrocostal joints

19. 19 TYPES OF SYNOVIAL JOINTS Hinge Joint Convex surface of one bones fits into concave surface of another bone Uniaxial like a door hinge Examples –Knee, elbow, ankle, interphalangeal joints Movements produced –flexion = decreasing the joint angle –extension = increasing the angle –hyperextension = opening the joint beyond the anatomical position

20. 20 TYPES OF SYNOVIAL JOINTS Pivot Joint Rounded surface of bone articulates with ring formed by another bone and ligament Monoaxial since it allows only rotation around longitudinal axis Examples –Proximal radioulnar joint supination pronation –Atlanto-axial joint turning head side to side “no”

21. 21 TYPES OF SYNOVIAL JOINTS-Condyloid or Ellipsoidal Joint Oval-shaped projection fits into oval (elliptical) depression Biaxial  flex/extend or abduct/adduct and circumduction are possible Examples –wrist and metacarpophalangeal joints for digits 2 to 5

22. 22 TYPES OF SYNOVIAL JOINTS Saddle Joint One bone saddled-shaped; other bone fits as a person would sitting in that saddle Biaxial Movements are flexion-extension, abduction-adduction, and circumduction –Circumduction allows tip of thumb travel in circle –Opposition allows tip of thumb to touch tip of other fingers Example –trapezium of carpus and metacarpal of the thumb

23. 23 TYPES OF SYNOVIAL JOINTS Ball and Socket Joint Ball fitting into a cuplike depression Multiaxial –flexion/extension –abduction/adduction –rotation/circumduction Examples (only two) –shoulder joint –hip joint

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25. 25 FACTORS AFFECTING CONTACT AND RANGE OF MOTION AT SYNOVIAL JOINTS Structure and shape of the articulating bone Strength and tautness of the joint ligaments Arrangement and tension of the muscles Contact of soft parts Hormones Disuse

26. 26 Glenohumeral (Shoulder) Joint Head of humerus and glenoid cavity of scapula Ball and socket Articular capsule from glenoid cavity to anatomical neck Glenoid labrum deepens socket Many nearby bursa (subacromial) Associated ligaments strengthen joint capsule Transverse humeral ligament holds biceps tendon in place All types of movement

27. 27 Rotator Cuff Muscles Attach humerus to scapula Encircle the joint supporting the capsule Hold head of humerus in socket

28. 28 Strength/Stability of joint-deep shoulder muscles/tendons Deep shoulder muscles: SubscapularisnearlyMusculotendinus Supraspinatuscomplete(rotator) cuff Infraspinatus  circle  frequent site of Teres minoraroundinjury- pitchers/ jointquarterbacks “tearing” supraspinatus muscle Shoulder separation- dislocation of acromioclavicular joint or displacement of humerus from glenoid cavity

29. 29 Hip Joint This ball-and-socket joint is formed by the head of the femur and the acetabulum of the hipbone. This is an extremely stable joint due to the bones making up the joint and the accessory ligaments and muscles. Movements at this joint include flexion, extension, abduction, adduction, circumduction, and medial and lateral rotation of the thigh. One of strongest structures in the body

30. 30 Tibiofemoral (Knee) Joint This is the largest and most complex joint of the body and consists of three joints within a single synovial cavity. Between femur, tibia and patella Hinge joint between tibia and femur Gliding joint between patella and femur Flexion, extension, and slight rotation of tibia on femur when knee is flexed

31. 31 Tibiofemoral (Knee) Joint Articular capsule Patella is part of joint capsule anteriorly Rest of articular capsule is extracapsular ligaments –Fibular and tibial collateral ligaments Posterior cruciate ligament Anterior cruciate ligament –Lateral and medial menisci = articular discs Many bursa

32. 32 Knee injuries-sports 3c’s rupture of tibial collateral ligament; tear of anterior cruciate ligament torn cartilage( medial meniscus) Usually- difficult repair/recovery Dislocated knee- displacement of tibia relative to femur Anterior (most common)/ posterior/ medial/lateral Knee Injuries and Disorders

33. 33 Rheumatism-any painful state of supporting structures of the body- (bones, ligaments, joints, tendons or muscles) Arthritus- rheumatism of joints Rheumatoid arthritis (RA) autoimmune disease- body attacks its own tissue Immune system attacks cartilage/joint linings Bilateral- joint on one side/opposite side Inflammation of synovial membrane untreated-membrane thickens-synovial fluid accumulates pressure- pain /tenderness Pannus-abnormal granulation-produced by membrane; erosion of articular cartilage; cartlilage destroyed; fibrous tissue joins bone ends; tissue ossifies-fusion of joint (immoveable) Treatment-not specific- reduce pain/inflammation; preserve muscle strength/ joint function Joint Disorders DISORDERS: HOMEOSTATIC IMBALANCES

34. 34 Osteoarthritus ( more common than RA; less damaging) deterioration of articular cartilage; new bone formation in joint (“spurs”/bumps) decrease joint movement) Treatment-surgery-remove spurs Gouty arthritis (genetic disorder-males) Uric acid-waste product of nucleic acid metaboloism  uric acid/unable to excrete; uric acid  sodium urate (crystals) deposited in soft tissues/joints  inflammation/swelling Treatment- diet/colchicine uric acid production Bursitis- acute chronic inflammation of a bursa housemaid’s knee/ carpet layers knee DISORDERS: HOMEOSTATIC IMBALANCES

35. 35 Dislocation (luxation)- displacement of a bone from a joint; tearing of ligaments, tendons and articular capsules Partial dislocation (subluxation)- incomplete displacement of bone from a joint Sprain- forced wretching/twitching of a joint with possible rupture or injury to its attachments without dislocation (luxation) possible damage-blood vessels/muscles/tendons/ligaments/or nerves Strain (less serious)- overstretching of a muscle DISORDERS: HOMEOSTATIC IMBALANCES