The "flexor hallucis longus" is a muscle located in the lower leg, responsible for flexing the big toe. There are a few synonyms that can refer to this muscle, including "long flexor of the big toe," "long flexor of the hallux," and "long flexor of the first toe." Additionally, in medical terminology, the muscle may be referred to simply as the FHL. This muscle plays an essential role in walking, running, and other physical activities. If it becomes tight or injured, it can cause discomfort and limitations in mobility. Regular stretching and exercise can help to keep the flexor hallucis longus healthy and strong.