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CHAPTER
8
Joints
Objectives
Classification of Joints
1. Define joint or articulation.
Fibrous Joints
3. Describe the general structure of fibrous joints. Name and give an example of each of the
three common types of fibrous joints.
Cartilaginous Joints
Synovial Joints
6. Compare the structures and functions of bursae and tendon sheaths.
8. Name and describe (or perform) the common body movements.
10. Describe the elbow, knee, hip, jaw, and shoulder joints in terms of articulating bones,
anatomical characteristics of the joint, movements allowed, and joint stability.
Homeostatic Imbalances of Joints
11. Name the most common joint injuries and discuss the symptoms and problems associated
with each.
Developmental Aspects of Joints
14. Discuss factors that promote or disturb joint homeostasis.
Suggested Lecture Outline
I. Classification of Joints (pp. 249–250; Figs. 8.1–8.3; Tables 8.1–8.2)
A. Structural classification focuses on the material binding the bones together and whether
or not a joint cavity is present (p. 249; Table 8.1).
1. Structurally, joints may be fibrous, cartilaginous, or synovial.
II. Fibrous Joints (pp. 250–251; Fig. 8.1; Tables 8.1–8.2)
A. In fibrous joints, bones are joined together by fibrous tissue and lack a joint cavity, and
provide little to no movement (p. 250).
B. There are three types of fibrous joints: sutures, syndesmoses, and gomphoses (pp. 250–
251; Fig. 8.1).
1. Sutures occur between bones of the skull and use very short connective tissue fibers to
hold the bones together.
III. Cartilaginous Joints (pp. 251–252; Fig. 8.2; Tables 8.1–8.2)
A. In cartilaginous joints, the bones are joined together by cartilage, they lack a joint cavity,
and have very little mobility (p. 251).
IV. Synovial Joints (pp. 252–269; Figs. 8.3–8.13; Tables 8.1–8.2)
A. Synovial joints have a structure that allows free movement about the joint (p. 252).
B. The general structure of a synovial joint contains six distinguishing features
(pp. 252–253; Fig. 8.3).
1. Articular cartilage covers the ends of the articulating bones.
C. Bursae and tendon sheaths contain lubricant that reduces friction at synovial joints
(p. 253; Fig. 8.4).
D. Factors Influencing the Stability of Synovial Joints (pp. 255–256)
1. The shapes of the articular surfaces of bones found at a synovial joint determine the
movements that occur at the joint, but play a minimal role in stabilizing the joint.
E. Movements Allowed by Synovial Joints (pp. 256–258; Figs. 8.5–8.6; Table 8.2)
1. Skeletal muscles attach to bones or other connective structures at two points: the
origin, attached to the immovable bone; and the insertion, attached to the movable
bone.
3. Angular movements increase or decrease the angle between two bones.
a. Flexion decreases the angle of the joint and brings the articulating bones closer
together.
b. Extension increases the angle between the articulating bones.
4. Rotation is the turning of a bone along its own long axis.
5. Special Movements
a. Supination is rotating the forearm laterally so that the palm faces anteriorly or
superiorly.
b. Pronation is rotating the arm medially so that the palm faces posteriorly or
inferiorly.
F. Types of Synovial Joints (p. 258; Fig. 8.7; Table 8.2)
1. Plane joints have flat articular surfaces and allow gliding and transitional movements.
2. Hinge joints consist of a cylindrical projection that nests in a trough-shaped structure,
and allow movement along a single plane.
3. Pivot joints consist of a rounded structure that protrudes into a sleeve or ring, and
allow uniaxial rotation of a bone around the long axis.
G. Selected Synovial Joints (pp. 262–269; Figs. 8.8–8.13; Table 8.2)
1. Knee Joint
a. The single cavity of the knee joint is actually three joints in one: the femoropatellar
joint, the lateral and medial joints between the femoral condyles, and the menisci of
the tibia, known collectively as the tibiofemoral joint.
i. The tibiofemoral joint is a hinge joint, allowing mostly flexion and extension,
although limited rotation is possible when the knee is bent.
2. Shoulder (Glenohumeral) Joint
a. The shoulder joint is a ball-and-socket joint that is the most freely moving joint in
the body, although it is not a very stable joint.
3. Elbow Joint
a. The joint between the ulna and humerus provides a stable and smoothly operating
hinge joint that allows flexion and extension only.
4. Hip (Coxal) Joint
a. The hip joint is a ball-and-socket joint that provides a wide range of motion.
b. Several strong ligaments reinforce the capsule of the hip joint.
5. Temporomandibular Joint
a. The temporomandibular joint allows both hingelike movement and side-to-side
lateral excursion.
V. Homeostatic Imbalances of Joints (pp. 269–272; Figs. 8.14–8.15)
A. Common Joint Injuries (pp. 269–270; Fig. 8.14)
1. Sprains and dislocations are the most common joint injuries.
2. Cartilage tears often occur at the knee, when a meniscus is subjected to compression
and shear stress at the same time.
B. Inflammatory and Degenerative Conditions (pp. 270–272; Fig. 8.15)
1. Bursitis, an inflammation of the bursa, is usually caused by a blow or friction, while
tendonitis is inflammation of the tendons, and is usually caused by overuse.
2. Arthritis describes many inflammatory or degenerative diseases that damage the joints,
resulting in pain, stiffness, and swelling of the joint.
a. Osteoarthritis is the most common chronic arthritis. It is the result of breakdown of
VI. Developmental Aspects of Joints (pp. 272–273)
A. In an embryo, joints develop at the same time as bones, and resemble adult joints by
week 8 (p. 272).
B. During childhood, use defines the size, shape, and flexibility of joints (p. 272).
Cross References
Additional information on topics covered in Chapter 8 can be found in the chapters listed below.
1. Chapter 1: Planes of the body
2. Chapter 4: Ligaments and tendons (dense connective tissue); hyaline cartilage;
fibrocartilage
Lecture Hints
1. Clearly distinguish between the two systems of joint classification (structural and
functional).
5. If only one synovial joint will be studied in detail, the best choice is the knee.
6. To help students understand the significance of the form of bones at joints, demonstrate
the structural similarities of synovial joints in different body locations that fall within the
same structural class.
Activities/Demonstrations
1. Audiovisual materials are listed in the Multimedia in the Classroom and Lab section of
this Instructor Guide (p. 387).
2. Call on students to demonstrate the various types of body movements: abduction,
adduction, flexion, extension, etc., occurring at specific joints (e.g., flex your knee, rotate
your hand).
6. Obtain a video or request that a local orthopedic surgeon visit the class and describe the
techniques and advantages of arthroscopic knee surgery.
Critical Thinking/Discussion Topics
1. Why are diarthroses found predominantly in the limbs while synarthroses and
amphiarthroses are found largely in the axial skeleton?
2. What are the advantages of the shoulder joint being the most freely moving joint in the
body?
Library Research Topics
1. People often injure their joints during sports activities. What are the major joint injuries
associated with football, basketball, baseball, and tennis?
4. Temporomandibular joint disorders are very painful. What methods of treatment are
there, and how successful are they? How do these joint disorders arise?
5. Much controversy surrounds the use of the drug dimethyl sulfoxide (DMSO). Why is the
FDA so reluctant to provide full approval of this drug for use on humans when it’s wide-
ly used for horses?
List of Figures and Tables
All of the figures in the main text are available in JPEG format, PPT, and labeled & unlabeled
format on the Instructor Resource DVD. All of the figures and tables will also be available in
Transparency Acetate format. For more information, go to www.pearsonhighered.com/educator.
Figure 8.1 Fibrous joints.
Figure 8.7 Synovial Joints.
Figure 8.8 The knee joint.
Figure 8.9 A common knee injury.
Figure 8.10 The shoulder joint.
Figure 8.11 The elbow joint.
Figure 8.12 The hip joint.
Answers to End-of-Chapter Questions
Multiple-Choice and Matching Question answers appear in Appendix H of the main text.
Short Answer Essay Questions
8. Joints are defined as sites where two or more bones meet. (p. 249)
9. Freely movable joints provide mobility; slightly movable joints provide strength with
10. Bursae are synovial membrane-lined sacs that function to prevent friction, and are
11. Nonaxial movements mean slipping movements only, uniaxial movements mean move-
12. Flexion and extension refer to decreasing or increasing the angle of a joint and bringing
13. Rotation means to turn a bone around its own long axis, while circumduction means to
move a limb so that it describes a cone in space, an action that involves a variety of
movements. (p. 258)
14. Uniaxial joints include hinge (elbow) and pivot (atlantoaxial and radioulnar) joints;
15. The knee menisci deepen the articulating surface of the tibia to prevent side-to-side
16. The knees must carry the total body weight and rely heavily on nonarticular factors for
17. Sprains and cartilage injuries are particularly problematic because cartilage and liga-
ments are poorly vascularized and tend to heal very slowly. (p. 264)
18. The fibrous layer, composed of dense irregular connective tissue, is the external layer of
the articular capsule and strengthens the joint so that the bones are not pulled apart. Syn-
ovial fluid occupies all free spaces within the articular capsule, including that within the
Critical Thinking and Clinical Application Questions
2. a. The ankle joint is not really a stable joint. The shape of the articular surfaces is not as
enclosed as other joints and has a greater degree of flexibility due to the fact that three
bones, not two, create the joint. Also, there are relatively few strong muscles and lig-
aments that cross this joint, compared to other joints, such as the hip or knee.
3. a. Mrs. Bell’s arthritis is probably due to gout, although gout is more common in males.
b. Arthritis due to gout is caused by a deposition of uric acid crystals in soft tissues of
joints. (p. 270)
4. The vector for the bacteria that causes Lyme disease is the deer tick, a very small tick
carried by deer and other small mammals. (p. 270)
Suggested Readings
De Bari, C., et al. “Mesenchymal Multipotency of Adult Human Periosteal Cells Demon-
strated by Single-Cell Lineage Analysis.” Arthritis & Rheumatism 54 (4) (March 2006):
1209–1221.
Lindner, Larry. “Superstition Vs. Science: Get the Truth about Foods Commonly Touted to
Relieve Arthritis Pain.” Arthritis Today 25 (3) (May 2011): 90–95.
Marques, A. R. “Lyme Disease: A Review.” Current Allergy and Asthma Reports 10 (1)
(Jan. 2010): 13–20.
Seppa, N. “Peptide Puts Mouse Arthritis Out of Joint.” Science News 159 (18) (May 2001):
279.
