An individual sustained a laceration of the perineum during delivery that involved the muscles of the perineal body but not the anal sphincter. Such a laceration would be classified as a:

A laceration involving the muscles of the perineal body but not the anal sphincter is classified as a second-degree laceration. In the context of perineal injuries during childbirth, first-degree lacerations involve only the vaginal mucosa and perineal skin, while third-degree lacerations extend through the anal sphincter, and fourth-degree lacerations involve both the anal sphincter and the rectal mucosa.

In this case, since the laceration goes deeper than just the skin and vaginal mucosa, affecting the muscles of the perineal body but stopping short of the anal sphincter, it is categorized as second-degree. Understanding the classification of perineal lacerations is crucial in guiding appropriate care and management post-delivery, enhancing the healing process and providing proper education to patients about their recovery.