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Joints Part A 8.

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Presentation on theme: "Joints Part A 8."— Presentation transcript:

1 Joints Part A 8

2 Joints (Articulations)
Weakest parts of the skeleton Articulation – site where two or more bones meet Functions of joints Give the skeleton mobility Hold the skeleton together

3 Classification of Joints: Structural
Structural classification focuses on the material binding bones together and whether or not a joint cavity is present The three structural classifications are: Fibrous Cartilaginous Synovial

4 Fibrous Structural Joints: Sutures
Figure 8.1a

5 Fibrous Structural Joints: Syndesmoses
Figure 8.1b

6 Cartilaginous Joints: Synchondroses
Figure 8.2a, b

7 Cartilaginous Joints: Symphyses
Figure 8.2c

8 Examples – all limb joints, and most joints of the body
Synovial Joints Those joints in which the articulating bones are separated by a fluid-containing joint cavity All are freely movable Examples – all limb joints, and most joints of the body

9 Synovial Joints: General Structure
Synovial joints all have the following Articular cartilage Joint (synovial) cavity Articular capsule Synovial fluid Reinforcing ligaments

10 Synovial Joints: General Structure
Figure 8.3a, b

11 Synovial Joints: Friction-Reducing Structures
Bursae – flattened, fibrous sacs lined with synovial membranes and containing synovial fluid Common where ligaments, muscles, skin, tendons, or bones rub together Tendon sheath – elongated bursa that wraps completely around a tendon

12 Synovial Joints: Friction-Reducing Structures
Figure 8.4

13 Synovial Joints: Stability
Stability is determined by: Articular surfaces – shape determines what movements are possible Ligaments – unite bones and prevent excessive or undesirable motion Muscle tone: Muscle tendons across joints acting as stabilizing factors Tendons that are kept tight at all times by muscle tone

14 Types of Synovial Joints
1. Plane joints Articular surfaces are essentially flat Allow only slipping or gliding movements Only examples of nonaxial joints Figure 8.7a

15 Gliding Movement Figure 8.5a

16 Types of Synovial Joints (continue)
2. Hinge joints Cylindrical projections of one bone fits into a trough-shaped surface on another Motion is along a single plane Uniaxial joints permit flexion and extension only Examples: elbow and interphalangeal joints

17 Types of Synovial Joints
Figure 8.7b

18 Only uniaxial movement allowed
3. Pivot Joints Rounded end of one bone protrudes into a “sleeve,” or ring, composed of bone (and possibly ligaments) of another Only uniaxial movement allowed Examples: joint between the axis and the dens, and the proximal radioulnar joint

19 4. Condyloid, or Ellipsoidal, Joints
Oval articular surface of one bone fits into a complementary depression in another Both articular surfaces are oval Biaxial joints permit all angular motions Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle) joints

20 5. Saddle Joints Similar to condyloid joints but allow greater movement Each articular surface has both a concave and a convex surface Example: carpometacarpal joint of the thumb

21 6. Ball-and-Socket Joints
A spherical or hemispherical head of one bone articulates with a cuplike socket of another Multiaxial joints permit the most freely moving synovial joints Examples: shoulder and hip joints

22 Selected Synovial Joints: Knee
Largest and most complex joint of the body Allows flexion, extension, and some rotation Three joints in one surrounded by a single joint cavity Femoropatellar Lateral and medial tibiofemoral joints

23 Synovial Joints: Knee Ligaments and Tendons – Anterior View
Tendon of the quadriceps femoris muscle Lateral and medial patellar retinacula Fibular and tibial collateral ligaments Patellar ligament Figure 8.8c

24 Synovial Joints: Knee – Other Supporting Structures
Anterior cruciate ligament Posterior cruciate ligament Medial meniscus (semilunar cartilage) Lateral meniscus

25 Synovial Joints: Knee – Other Supporting Structures
Figure 8.8b

26 Synovial Joints: Knee – Posterior Superficial View
Adductor magnus tendon Articular capsule Oblique popliteal ligament Arcuate popliteal ligament Semimembranosus tendon Figure 8.8e

27 Selected Synovial Joints: Shoulder (Glenohumeral) joint
Ball-and-socket joint in which stability is sacrificed to obtain greater freedom of movement Head of humerus articulates with the glenoid fossa of the scapula

28 Synovial Joints: Shoulder Stability
Weak stability is maintained by: Thin, loose joint capsule Four ligaments – coracohumeral, and three glenohumeral Tendon of the long head of biceps, which travels through the intertubercular groove and secures the humerus to the glenoid cavity Rotator cuff (four tendons) that encircles the shoulder joint and blends with the articular capsule

29 Synovial Joints: Shoulder Stability
Figure 8.10a

30 Synovial Joints: Shoulder Stability
Figure 8.10b

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