Synovial joints vary in their structure and range of motion. This lesson examines the small gliding joints between vertebrae, the specialized joints that move the head, and the temporomandibular joint (TMJ), which enables jaw movement.
Adjacent vertebrae connect through intervertebral discs and through synovial joints between their superior and inferior articular processes. These synovial joints are called zygapophysial joints, or facet joints. They are plane joints, so each permits only limited gliding. Their combined movements, however, contribute to spinal flexibility.
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What are zygapophysial joints?
They are plane synovial joints between the articular processes of adjacent vertebrae. They permit limited gliding, and their orientation helps determine spinal movement.
What movements are most available in the cervical spine?
The cervical spine allows flexion, extension, lateral flexion, and rotation because of the orientation of its articular processes.
What is the difference between the atlanto-occipital and atlantoaxial joints?
The atlanto-occipital joint allows flexion and extension of the head, as in nodding “yes.” The atlantoaxial joint allows rotation, as in shaking the head “no.”
What is the role of the TMJ articular disc?
The flexible disc lies between the temporal bone and mandibular condyle and helps smooth movement between them.
How does the mandible move when the mouth opens?
It hinges downward while the mandibular condyle and disc glide anteriorly from the mandibular fossa onto the articular tubercle.
Quiz questions
What type of synovial joints are zygapophysial joints?Answer: Plane joints that permit limited gliding between adjacent vertebrae.
Why is rotation largely restricted in the lumbar region?Answer: The orientation of the lumbar articular processes largely limits rotation.
Which joint produces the head movement used to nod “yes”?Answer: The atlanto-occipital joint permits head flexion and extension.
What forms the pivot at the atlantoaxial joint?Answer: The dens of the axis meets the inner surface of the atlas’s anterior arch.
What combination of movements occurs as the mouth opens at the TMJ?Answer: The mandible hinges downward as the condyle and disc glide forward.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.