Lesson Block 8: The Skeletal System III: Joints
Introduction
In the Lesson Blocks 6 and 7, your study of the skeletal system included learning about the
different bones of the axial and appendicular skeletons. You learned about the names of
bones, their locations, markings, shape, and functions- a lot of information to memorize!
This is the last Lesson Block before the final and will be on the final exam!!
In the last lesson, you were asked to think about the following questions to prepare for this
system:
What are the functions of joints?
How many different types of joints are there?
Why is it important to study joints and their functions?
Consider the following additional questions as you work through this lesson:
How are joints classified?
What is the difference between fibrous, cartilaginous, and synovial joints?
What are some homeostatic imbalances of joints?
Lesson Block 8 Readings, Resources, and Assignments
Required
Textbook
Readings
Read Chapter 8: Joints: pp.248-274
Multimedia
Resources
"Anatomy and Physiology Revealed" CD
MyAandP.com Chapter 8:Joints
Required
Synovial Joint Research Group Project & Presentation- Due 02/01/12
Assignments
Lab Quiz on Exercise 13 – 01/30/2012
Lab Exercise 13: Articulations and Body Movements - Due 01/30/12
Ch. 8 - Joints Test - Due 02/03/12
Approaching the Objectives
Classification of Joints
Joints can be classified by their structure and by their function.
Structural classification of joints involves the material binding the bones together - regardless of the
presence or absence of a joint cavity.
Structurally, joints are classified as fibrous, cartilaginous, and synovial.
Functional classification of joints involves the amount of movement allowed at the joints. Joints are
classified functionally as synarthroses (immovable joints), amphiarthroses (slightly movable
joints), and diarthroses (freely movable joints).
Structural Classification
Fibrous joints are joined by fibrous tissue and lack a joint cavity.
There are three types of fibrous joints: Sutures, syndesmoses, and gomphoses.
Sutures are found between bones of the skull and are immovable.
Syndesmoses
are bones connected by a ligament or band of fibrous tissue, such as the joint between the distal
ends of the tibia and fibula. Depending on the length of the ligament, these types of joints have slight
to considerable mobility.
Gomphoses are peg-in-socket fibrous joints. The only
gomphoses in the body are the articulation of teeth with their bony alveolar socket. Figure 8.1 of
your text illustrates the different types of fibrous joints.
Cartilaginous joints are found where bones are united by cartilage; but they lack a joint
cavity. There are two types of cartilaginous joints: Synchondroses and symphyses.
Synchondroses occur when hyaline cartilage unites the two bones. Virtually all synchondroses
are immovable. An example of this type of joint is the immovable joint between the costal cartilage
of the first rib and the manubrium of the sternum.
Symphyses occur when the articular surfaces of the bones are covered with articular cartilage,
which is then fused to a pad of fibrocartilage. These joints act as shock absorbers and exhibit limited
movement (for example, the intervertebral joints). Figure 8.2 of your text illustrates the different
types of cartilaginous joints.
Synovial joints are found where articulating bones are separated by a fluid-containing
joint cavity. All synovial joints move freely (diarthroses). Most joints of the body, including all of
the joints in the limb, are synovial joints. Read about the distinguishing features of synovial joints in
your text, using Figure 8.3 as a guide. Also read about the associated bursae and tendon sheaths and
how they relate to synovial joints (using Figure 8.4), as well as factors such as articular surfaces,
ligaments, muscle tone and how they relate to the stability of synovial joints.
Table 8.1 of your text summarizes the different joint classes discussed above. In addition, you may
want to create a matrix of your own, similar to the one below. The first row has been completed for
you:
Structural
Description Subtypes
Classification
Fibrous
Description
Examples
of
of each
Subtypes
Bones joined
Sutures
Bone edges
by fibrous
interlock
tissue; no joint Syndesmoses
Bones
cavity
connected by
ligament
Bones of the
skull
Gomphoses
Tooth with
its bony
alveolar
socket
Peg-in-socket
Movement
allowed
Bones of the
skull
Ends of the Slightly movable
tibia and (amphiarthroses)
fibula
Immovable
(syarthroses)
Cartilagenous
Synovial
Synovial Joint Movements
The movements at synovial joints can be described by the geometric planes they intersect. I find this
part of the lesson confusing. Go back and review the three anatomical planes; frontal, midsagittal
and transverse. Study Figure 8.7 and 8.8 and move each joint. Notice which category that
movements falls into; nonaxial, uniaxial, biaxial or multiaxial. Also practice the various movements
shown in Figure 8.5 (pages 255 – 258). As you study the specific synovial joints, note the ligaments
involved in stabilizing that joint.
Movement at joints is possible because of muscles that are attached to bone or other connective
tissue structures. The origin of the muscle is attached to the immovable (or less movable)
bone and the insertion of the muscle is attached to the movable bone. When muscles
contract, movement occurs.
Synovial joints demonstrate a range of motion:
nonaxial movement (slipping movements),
uniaxial movement (movement in one plane),
biaxial movement (movement in two planes), or
multiaxial movement (movement in or around three planes).
Within these ranges of motion, there are three general types of movements (illustrated in Figure
8.5 of your text): Gliding, angular movements, and rotation.
Gliding movements occur when flat bone surfaces glide or slip over each other. An example of
gliding movements occurs with the bones in your hand when you wave it at the wrist.
Angular movements increase or decrease the angle between two bones. There are six general
types of angular movements: Flexion, extension, dorsiflexion and plantar flexion, abduction,
adduction, and circumduction.
Rotation occurs when a bone turns around its own axis. It occurs at the hip and shoulder joints.
In addition to these general types of movements, five categories of special movements can also
occur. These special movements do not fit into any of the above categories and only occur within a
few places in the body. These movements include:
supination and pronation:
inversion and eversion:
protraction and retraction:
elevation and depression:
Opposition:
Figure 8.6 of your text illustrates the special body movements.
 To help you learn the movements allowed in synovial joints, create flashcards for each
movement with the movement name on one side of the card & its description & an
example on the other side. Then spend time in front of the mirror to demonstrate the
movement in the mirror as you read the movement type written on the flashcard.
Types of Synovial Joints
There are six major categories of synovial joints:
Plane:
Hinge:
Pivot:
Condyloid:
Saddle:
Ball-and-socket:
In your text, read about each type of joints, using Figure 8.7 as a guide. Use MyAandP.com to help
you review for each type of joint to help you remember their characteristics and examples of each.
Also read about the selected synovial joints in your text to help you with your joint project:
The Knee:
Shoulder:
Hip:
Elbow:
Temporomandibular:
Be able to describe the joint, its characteristics, movements allowed, classification, articulating
surfaces & tissues, & homeostatic imbalances that may occur. Use Fig. 8.8 - 8.13 as a guide.
 Create flashcards for each of the body joints covered in Table 8.2. Include on one side of the card
the name of the joint, and on the other include the articulating bones, structural type, functional
type, and movements allowed.
Common Joint Injuries and Conditions
Read about the homeostatic imbalances of joints in your text, including sprains, cartilage injuries,
dislocations, bursitis and tendonitis, and arthritis. Complete a matrix like the one below as you read:
Homeostatic Imbalance Description
How it occurs
Treatment
Examples
Sprains
Cartilage Injuries
Dislocations
Bursitis and
Tendonitis
Arthritis
Note: Although osteoarthritis is common and anti-inflammatory drugs can relieve the pain,
Rheumatoid Arthritis is considered the “inflammatory arthritis”. RA (rheumatoid arthritis) is a serious
and sometime debilitating disorder. Gouty arthritis is treatable but can be very serious if left
untreated.
Summarizing Your Learning
In this lesson, you studied joints. You should be able to name, describe, locate major joints,
and classify them according to their structure and function.
In addition, think about the following questions:



How are joints classified?
What is the difference between fibrous, cartilaginous, and synovial joints?
What are some homeostatic imbalances of joints?
Additional Resources
This website gives you a video showing shoulder movement and details the rotator cuff and
bursa. It also has a video describing hip replacement surgery and knee replacement
surgery. If you look around the website, you will also learn about meniscus tears and knee
pain. http://video.about.com/orthopedics/Hip-Replacement.htm
This website is an easy to read review of joints. It covers carpal tunnel syndrome and gives
you images of the actual joints.
http://www.ithaca.edu/faculty/lahr/LE2000/LE_index.html