1. Chapter 9 Articulations
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. Fibrous Joints 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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