How many total articulating joints comprise the lumbosacral motion unit in the dog?

How many total articulating joints comprise the lumbosacral motion unit in the dog?

• A. 2
• B. 4
• C. 3
• D. 5

Answer: (C)

The lumbosacral motion unit in the dog is formed by three articulations at the junction between the last lumbar vertebra and the first sacral vertebra. These are the two zygapophyseal (facet) joints on the left and right, between L7 and S1, and the intervertebral articulation between the bodies of L7 and S1 (the intervertebral disc and its endplates). Together, these three articulations provide the mobility and stability at the lumbosacral junction, allowing flexion, extension, and some lateral bending. Therefore, the total number of articulating joints in this motion unit is three. In typical anatomy this count is three, though variations like sacralization or lumbarization can alter it.

The lumbosacral motion unit in the dog is formed by three articulations at the junction between the last lumbar vertebra and the first sacral vertebra. These are the two zygapophyseal (facet) joints on the left and right, between L7 and S1, and the intervertebral articulation between the bodies of L7 and S1 (the intervertebral disc and its endplates). Together, these three articulations provide the mobility and stability at the lumbosacral junction, allowing flexion, extension, and some lateral bending. Therefore, the total number of articulating joints in this motion unit is three. In typical anatomy this count is three, though variations like sacralization or lumbarization can alter it.