Final answer:
The transverse tarsal joints are parallel when the foot is in a neutral position, allowing for stable gliding movements that facilitate inversion and eversion.
Step-by-step explanation:
The transverse tarsal joints, which consist of the talonavicular and calcaneocuboid joints, are parallel when the foot is in a neutral position, that is, neither everted nor inverted. These joints work in conjunction to allow for the complex movements of foot inversion and eversion. It's important to note that as plane joints, their primary motion is gliding, and they contribute to the stability and flexibility of the foot.