Final answer:
An ulnar gutter splint is used for fractures of the second to fifth metacarpal bones, designed to immobilize the area and allow for proper healing.
Step-by-step explanation:
For fractures of the second to fifth metacarpal bones, a ulnar gutter splint is typically used. This type of splint is designed to immobilize and protect the injured metacarpals and associated phalanges. The splint extends from the forearm down to the phalanges, with the hand in a natural, slightly flexed position to promote proper healing. It is important to recognize that the second and third metacarpal bones are generally immobile, while the fourth and fifth bones allow for some anterior-posterior mobility, which is essential for actions such as gripping. Despite this, during the healing process, immobilization is crucial for all metacarpals involved in the fracture to ensure proper alignment and recovery.