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BIO 140 Human Biology I - Questions and Solutions

Classification of Joints - Solutions

Review Questions

1. The joint between adjacent vertebrae that includes an invertebral disc is classified as which type of joint?

  1. diarthrosis
  2. multiaxial
  3. amphiarthrosis
  4. synarthrosis

2. Which of these joints is classified as a synarthrosis?

  1. the pubic symphysis
  2. the manubriosternal joint
  3. an invertebral disc
  4. the shoulder joint

3. Which of these joints is classified as a biaxial diarthrosis?

  1. the metacarpophalangeal joint
  2. the hip joint
  3. the elbow joint
  4. the pubic symphysis

4. Synovial joints ________.

  1. may be functionally classified as a synarthrosis
  2. are joints where the bones are connected to each other by hyaline cartilage
  3. may be functionally classified as a amphiarthrosis
  4. are joints where the bones articulate with each other within a fluid-filled joint cavity


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Critical Thinking Questions

1. Define how joints are classified based on function. Describe and give an example for each functional type of joint.

Solution: Functional classification of joints is based on the degree of mobility exhibited by the joint. A synarthrosis is an immobile or nearly immobile joint. An example is the manubriosternal joint or the joints between the skull bones surrounding the brain. An amphiarthrosis is a slightly moveable joint, such as the pubic symphysis or an intervertebral cartilaginous joint. A diarthrosis is a freely moveable joint. These are subdivided into three categories. A uniaxial diarthrosis allows movement within a single anatomical plane or axis of motion. The elbow joint is an example. A biaxial diarthrosis, such as the metacarpophalangeal joint, allows for movement along two planes or axes. The hip and shoulder joints are examples of a multiaxial diarthrosis. These allow movements along three planes or axes.

2. Explain the reasons for why joints differ in their degree of mobility.

Solution: The functional needs of joints vary and thus joints differ in their degree of mobility. A synarthrosis, which is an immobile joint, serves to strongly connect bones thus protecting internal organs such as the heart or brain. A slightly moveable amphiarthrosis provides for small movements, which in the vertebral column can add together to yield a much larger overall movement. The freedom of movement provided by a diarthrosis can allow for large movements, such as is seen with most joints of the limbs.


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OpenStax, Classification of Joints. OpenStax CNX. Jun 4, 2013 http://cnx.org/contents/dfedbd1c-1068-4dc1-abbc-cf6956cb20a4@3. © Jun 4, 2013 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License 3.0 license.