KAAP309 Lecture Notes - Lecture 8: Periodontal Fiber, Fibrous Joint, Synovial Joint
18 May 2018
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Chapter 8A: Joints
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I. Joints (articulations)
A. Weakest parts of the skeleton
B. Articulation – site where two or more bones meet
C. Functions of joints
1. Give the skeleton mobility
2. Hold the skeleton together
II. Classification of Joints: Structural
A. Structural classification focuses on the material binding bones together and
whether or not a joint cavity is present
B. The three structural classifications are:
1. Fibrous
2. Cartilaginous
3. Synovial
III. Classification of Joints: Functional
A. Functional classification is based on the amount of movement allowed by the
joint
B. The three functional classes of joints are:
1. Synarthroses – immovable (sutures in the skull)
2. Amphiarthroses – slightly movable
3. Diarthroses – freely movable
IV. Fibrous Structural Joints
A. The bones are joined by fibrous tissues
B. There is no joint cavity
C. Most are immovable
D. There are three types – sutures, syndesmoses, and gomphoses
1. Sutures
a) Occur between the bones of the skull
b) Comprised of interlocking junctions completely filled with
connective tissue fibers
c) Bind bones tightly together, but allow for growth during youth
d) In middle age, skull bones fuse and are called synostoses
2. Syndesmoses
a) Bones are connected by a fibrous tissue ligament
b) Movement varies from immovable to slightly variable
c) Examples include the connection between the tibia and fibula,
and the radius and ulna
3. Gomphoses
a) The peg-in-socket fibrous joint between a tooth and its alveolar
socket
b) The fibrous connection is the periodontal ligament
V. Cartilaginous Joints
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A. Articulating bones are united by cartilage
B. Lack a joint cavity
C. Two types – synchondroses and symphyses
1. Synchondroses
a) A bar or plate of hyaline cartilage unites the bones
b) All synchondroses are synarthrotic
c) Examples include:
i. Epiphyseal plates of children
ii. Joint between the costal cartilage of the first rib and the
sternum
2. Symphyses
a) Hyaline cartilage covers the articulating surface of the bone and is
fused to an intervening pad of fibrocartilage
b) Amphiarthrotic joints designed for strength and flexibility
c) Examples include intervertebral joints and the pubic symphysis of
the pelvis
VI. Synovial Joints
A. Those joints in which the articulating bones are separated by a fluid-containing
joint cavity
B. All are freely movable diarthroses
C. Examples – all limb joints, and most joints of the body
D. General Structure
1. Synovial joints all have the following
a) Articular cartilage
b) Joint (synovial) cavity
c) Articular capsule
d) Synovial fluid
e) Reinforcing ligaments
E. Friction-Reducing Structures
1. Bursae – flattened, fibrous sacs lined with synovial membranes and
containing synovial fluid
2. Common where ligaments, muscles, skin, tendons, or bones rub
together
3. Tendon sheath – elongated bursa that wraps completely around a
tendon
F. Stability
1. Stability is determined by:
a) Articular surfaces – shape determines what movements are
possible
b) Ligaments – unite bones and prevent excessive or undesirable
motion
2. Muscle tone is accomplished by:
a) Muscle tendons across joints acting as stabilizing factors
b) Tendons that are kept tight at all times by muscle tone
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Document Summary
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. 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. Cartilaginous joints: articulating bones are united by cartilage, lack a joint cavity, two types synchondroses and symphyses, synchondroses, a bar or plate of hyaline cartilage unites the bones, all synchondroses are synarthrotic, examples include: Gliding movements: one flat bone surface glides or slips over another similar surface, examples intercarpal and intertarsal joints, and between the flat articular processes of the vertebrae. Rotation: the turning of a bone around its own long axis, examples, between first two vertebrae, hip and shoulder joints. Special movements: supination and pronation, at ankle: pronation eversion* (see next slide)
