This document discusses the skeletal system and different types of joints. It begins by defining a joint as the connection between two or more bones, and notes their functions of binding parts of the skeleton together and enabling movement. It then describes three classifications of joints: functional (based on movement), structural (based on connecting material), and synovial joints (which have a fluid-filled cavity). Several examples of each type of joint are provided, along with diagrams of their structures.

1. Dr Asma Lashari
University of Health Sciences
Lahore, Pakistan

2. Joints of the Skeletal System
 A joint or articulation is a connation between two or
more bones.
 Long bones articulate by their ends, flat bones by
margins, whereas in short or irregular bones surfaces
are articular.
 Functional junctions between bones.
 Bind parts of skeletal system together.
 Permit parts of the skeleton to change shape during
childbirth.
 Enable body to move in response to skeletal muscle
contraction.

3. Functional Classification Of Joints
 Classification=based on the amount of movement allowed
 3 types:
 Synarthroses = immovable joints
 Example = sutures of skull
 Amphiarthroses = slightly movable joints.
 Example = intervertebral discs between vertebrae
 Diarthroses = freely movable joints
 Examples = joints of appendicular skeleton

4. Structural Classification Of Joints
 Classification= Based on material, which joins bones
 3 types:
 Fibrous
 Fibrous joints are connected by dense connective tissue consisting mainly of collagen.
 These joints are also called fixed or immovable joints because they do not move.
 Fibrous joints have no joint cavity and are connected via fibrous connective tissue.
 The skull bones are connected by fibrous joints called sutures.
 Cartilaginous
 These joints are connected entirely by cartilage (fibrocartilage or hyaline).
 These joints allow more movement between bones than a fibrous joint but less than the
highly mobile synovial joint
 Synovial
 Also known as diarthrosis, joins bones with a fibrous joint capsule that is continuous with
the periosteum of the joined bones,
 Constitutes the outer boundary of a synovial cavity, surrounds the bones' articulating
surfaces.
 The synovial cavity/joint is filled with synovial fluid.

5. Fibrous Joints
 joints composed of fibrous tissue
 no joint cavity is present
 3 types:
 Syndesmosis
 Suture
 Gomphosis

6. Fibrous Joints cont.
Syndesmosis
is a fibrous joint between two bones and linked by
ligaments and a strong membrane.
Example = distal tibiofibular joint

7. Fibrous Joints cont.
Sutures = short fibrous joint only present in skull
 Synarthroses, provides for a strong connection between the adjacent bones
 Only found in skull

8. Fibrous Joints cont.
Gomphosis
tooth within its bony socket (alveolar fossa)
 short periodontal ligament

9. Cartilaginous Joints
 joints composed of cartilage
 no joint cavity
 2 types:
 Synchondrosis
 Symphysis

10. Cartilaginous Joints cont.
Synchondrosis
bones are joint by a plate of hyaline cartilage
 sites of bone growth during youth
 eventually ossify = synarthrotic
 Examples: joint between the first rib and manubrium and the epiphyseal plate

11. Cartilaginous Joints cont.
Symphysis
pad or plate of fibrocartilage
 compressible "shock absorber"
 slight movement = amphiarthroses
 Examples: intervertebral discs and
symphysis pubis

12. Synovial Joints
Fluid-filled joint cavity
 free movement = diarthrosis

13. General Structure Of A Synovial Joint
General Structure Of A Synovial Joint = 5 distinct features:
1. Articular cartilage = hyaline cartilage covers the surface of each bone
2. Joint cavity = a potential space between the two bones, filled with synovial fluid
3. Synovial fluid = viscous lubricating fluid within cavity
 reduces friction between cartilages of 2 bones
 provide lubrication
 nourish cartilage
 contain phagocytes
4. Articular capsule = double layered capsule surrounding cavity:
 External, tough flexible fibrous capsule (continuous with periosteum of the
bones)
 Synovial membrane = loose CT lining of fibrous capsule, that also covers all
internal joint surfaces excluding hyaline cartilage
5. Reinforcing ligaments = ligaments that strengthen joint
 Definition: A ligament joins a bone to another bone across a synovial joint
 usually thickened portions of fibrous capsule (intrinsic or capsular)

14. General Structure of a Synovial Joint

15. Synovial Joints cont.
 Other joint features:
 fatty pads (hip & knee)
 menisci or articular discs or that separate cavity into 2 compartments (knee,
jaw, sternoclavicular)
 bursa = flattened fibrous sacs with a synovial membrane and fluid that act as "ball
bearings" to prevent friction on adjacent structures during joint activity
 cushion the movement of one body part over another;
 located between skin and bone (where skin rubs over bone), and between muscle,
tendons, ligaments and bone.

16. Types Of Synovial Joints
 Ball-and-socket joints = most freely
movable joints; all angular movement
 The head of one bone fits into the
socket of another
 Examples = hip and shoulder
 Condyloid joints = permit all angular
motion, except rotation
 Examples = wrists and knuckles

17. Types Of Synovial Joints cont.
 Gliding joints = cartilaginous joints
 Example = intervertebral discs
 Hinge joints = permit flexion &
extension only
 Examples = elbow and knee

18. Types Of Synovial Joints cont.
 Pivot joints = permit rotation
 Example = first intervertebral
joint (atlantoaxial joint)
 Saddle joints = thumb

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