Meaning of sellar | Babel Free

Definitions

Relating to the sella turcica.

not-comparable

Examples

“[…] has been reduced to only two basic types: ovoid and sellar surfaces (Fig. 3). The ovoid surface is uniformly convex or concave with the degree of curvature varying at each point⟳ along the surface; the sellar surface is convex in one plane and concave in a plane perpendicular to it. Modification of these basic types occur⟳. The knee comprises two ovoid joints within one capsule and is termed a bicondylar joint. The greater multangular-metacarpal joint at the base⟳ of the thumb is a sellar joint. The ankle is also a sellar joint in which abduction and adduction is prevented by the limitations of a mortice arrangement. Movement about an ovoid surface requires more ligaments and muscles to maintain⟳ stability. The surface of a sellar joint is more congruous and makes the direction of motion more specific and more limited. A sellar joint is more efficient and more easily stabilized. […] Fig. 3. The two types of joints^([sic]) surface, O—ovoid; S—sellar. […] Conjunct rotation in an ovoid joint depends on muscular action but in a sellar joint it is dependent upon the shape⟳ of the joint and the congruity of the opposing surfaces. That is why sellar joints are more efficient. They produce⟳ conjunct rotation without muscular effort, and prevent⟳ adjunct rotation during motion.”

CEFR level