Which of the following are used as a locking mechanism to hold a suture needle when applying stitches or closing an incision?

A needle holder is specifically designed to securely grasp and manipulate a suture needle while suturing or closing an incision. Its jaws are crafted in such a way that they can firmly hold the needle in place, allowing the veterinarian or surgical assistant to exert precise control while stitching tissues together. This type of instrument usually features a ratchet mechanism that locks the needle in place, ensuring that it doesn't slip during use, which is crucial for precise suturing.

Other options, while related to surgical tasks, do not serve this purpose. Scissors are typically used to cut sutures or tissues, forceps are generally for grasping or holding tissues, and a scalpel is meant for making incisions or cutting. None of these instruments are designed to securely lock a needle while suturing, making needle holders the most appropriate choice for this function.