Human Anatomy

1. Human Anatomy Chapter 9 Articulations

2. Articulations • A joint, or articulation, is the place of contact between bones, between bone and cartilage, or between bones and teeth. • The scientific study of joints is called arthrology (arthro- means joint)

3. Naming of Joints • Usually derived from the names of the articulating bones. • Example: Glenohumeral joint = joint between glenoid cavity of scapula and humerus

4. Mobility and Stability in Joints • Motion permitted ranges from none to various extensive motions. • Structure determines both its mobility and its stability. - more mobile = less stable

5. Classification of Joints • Type of connective tissue that binds the articulating surfaces of the bones. • Whether a space occurs between the articulating bones.

6. Classification of Joints • A fibrous joint occurs where bones are held together by dense regular (fibrous) connective tissue. • A cartilaginous joint occurs where bones are joined by cartilage. • A synovial joint - has a fluid-filled synovial cavity - bones are enclosed within a capsule - bones are joined by various ligaments

7. Classification of Joints • Functionally based on the extent of movement they permit: - Synarthrosis is an immovable joint. - Amphiarthrosis is a slightly movable joint. - Diarthrosis is a freely movable joint.

8. FibrousJoints • Most are immovable or only slightly movable. • Have no joint cavity. • Three types. - gomphoses - sutures - syndesmoses

9. Types of Fibrous Joints − Structural Category: Syndesmoses • Fibrous joints in which articulating bones are joined by ligaments only. • Allow for some movement. - Functionally classified as amphiarthroses (some movement) • Examples; Radius and ulna, tibia and fibula

10. Types of Fibrous Joints − Structural Category:Suture • Fibrous joints in skull connected by dense regular connective tissue • Allow growth of skull bones and brain • Allow for some movement (as infants). - Functionally classified as synarthrosis (no movement) • Examples; sutures of skull • When bones fuse, joint becomes a synostosis (fully fused bones; also in coxa)

11. Types of Fibrous Joints − Structural Category: Gomphosis • Fibrous joint between tooth and jaw • Teeth are connected to maxilla and mandible with periodontal ligaments • Allow for no movement. - Functionally classified as synarthrosis (no movement)

12. Cartilaginous Joints • Bones are attached to each other by cartilage. • Lack a joint cavity. • Two types. - synchondroses - symphyses

13. Cartilaginous Joints: Synchondrosis • Hyaline cartilage plate between bones • Example; epiphyseal plates in growing bones, joints between ribs and sternum • Functional classification; synarthrosis

14. Cartilaginous Joints:Symphysis • Fibrocartilage between bones • Example; pubic symphysis and intervertebral discs • Functional classification; amphiarthrosis

15. Synovial Joints • Freely movable articulations • Classified as diarthroses • Bones are separated by a space called a joint cavity • Most of the commonly known joints in the body • glenohumeral (shoulder) joint • temporomandibular joint • elbow joint • knee joint

16. General Anatomy of Synovial Joints - Basic features: • Articular capsule; dense connective tissue that strengthens joint • Joint cavity; space containing synovial fluid that allows separation of articulating bones • Synovial fluid; viscous oily liquid

17. Articular cartilage; reduces friction and absorbs impact • Ligaments; make up capsule of joint • Nerves; detect damage and help detect joint angle • Blood vessels; nourish living cells Insert Fig. 9.4 Synovial Joints

18. Synovial fluid • Secreted by synovial membrane • Has three functions; • Lubricates articulating surfaces (like oil) • Nourishes articular cartilage (it has no vascular tissue); movement enhances circulation • Acts as a shock absorber; distributing stress across the joint evenly

19. General Anatomy of Synovial Joints – Accessory Structures • Bursae - fibrous, saclike structure that contains synovial fluid and is lined by a synovial membrane - Reduce friction where a tendon or ligament rubs against a bone

20. General Anatomy of Synovial Joints – Accessory Structures • Fatpads - often distributed along the periphery of a synovial joint - act as packing material and provide some protection for the joint - fill the spaces that form when bones move and the joint cavity changes shape

21. General Anatomy of Synovial Joints – Accessory Structures • Tendons - attaches a muscle to a bone - help stabilize joints - often posses a tendon sheath to reduce friction (carpal tunnel syndrome)

24. Types of Synovial Joints • Classified by the shapes of their articulating surfaces • Types of movement they allow - uniaxial if the bone moves in just one plane - biaxial if the bone moves in two planes - multiaxial (or triaxial) if the bone moves in multiple planes

25. Types of Synovial Joints • From least movable to most freely movable, the six specific types of synovial joints are: • planar (gliding) joints • hinge joints • pivot joints • condyloid (ellipsoid) joints • saddle joints • ball-and-socket joints

26. Gliding Joints (planar) • Simplest synovial articulation • Least movable diarthrosis joint • Uniaxial (side to side movement only) • Articular surfaces are flat (planar) • Examples; intertarsal and intercarpal joints

27. Hinge Joints • Uniaxial joint; like a hinge on a door • Concave with convex surfaces • Example; elbow joint and knee joint

28. Pivot Joints • Articulating surface of one bone fits into a ring formed by a ligament and another bone • Pivoting bone rotates on its long axis • Examples; proximal radioulnar joint, atlas and axis of neck

29. Condyloid Joints • Biaxial joints (left/right and forward and back) • Oval, convex surface articulating with a concave surface • Examples; metacarpophalangeal joints in hand

30. Saddle Joints • Bones have both concave and convex regions • Similar to a saddle (or Pringle chip) • Greater range of movement than most types • Example; thumb joint; allows opposition

31. Ball and Socket Joints • Multiaxial joints with greatest range of motion • Ball (head) of one bone fits into cup-like depression (cavity or acetabulum) of less mobile bone • Examples; Shoulder and hip joints

32. Movements at Joints

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