Final answer:
The close packed position of the ulnohumeral (elbow) joint is when the elbow is fully extended, with the olecranon process of the ulna fitting into the olecranon fossa of the humerus and the collateral ligaments taut for maximal stability.
Step-by-step explanation:
The close packed position of the ulnohumeral (elbow) joint is the position in which the joint is most congruent and the ligaments and capsule are taut, providing maximal stability. This position occurs at full extension or 0 degrees of elbow joint extension. At this point, the olecranon process of the ulna fits into the olecranon fossa of the humerus, and the collateral ligaments are taut, preventing further motion and stabilizing the elbow.