Final answer:
The flexor pollicis longus tendon has its own synovial sheath, which allows it to move smoothly within the carpal tunnel, a passageway at the wrist that also contains the median nerve and other tendons of the forearm.
Step-by-step explanation:
The tendon of the hand that has its own synovial sheath is the flexor pollicis longus tendon, which passes through the carpal tunnel along with other tendons and the median nerve. This synovial sheath is a specialized connective tissue that wraps around the tendon, creating a lubricated tunnel for the tendon to move smoothly when the thumb is flexed. The lubricating fluid within this sheath is crucial for preventing friction and allowing the flexor tendons to glide effortlessly during thumb and finger movements.
Specifically, the carpal tunnel is an anatomical structure in the wrist through which the flexor tendons and the median nerve enter the hand, formed by carpal bones and the flexor retinaculum. Overuse or injury can lead to inflammation within the carpal tunnel, resulting in carpal tunnel syndrome, characterized by pain, numbness, and muscle weakness in the hand areas supplied by the affected nerve.