What condition is a specific form of tendonitis involving inflammation of the synovial membrane surrounding a joint?

The condition described as a specific form of tendonitis involving inflammation of the synovial membrane surrounding a joint is known as tenosynovitis. This condition specifically refers to the inflammation that occurs in the protective sheath (synovial membrane) that surrounds a tendon. When the sheath becomes inflamed, it can lead to pain, swelling, and difficulty moving the affected joint.

Understanding the distinction is crucial; while tendonitis refers generally to inflammation of a tendon itself, tenosynovitis emphasizes the involvement of the synovial sheath, which is essential in the mechanics of tendon movement near joints. This specialization of tenosynovitis is why it is the correct answer in this context. The other conditions listed do not specifically refer to the inflammation of the synovial membrane around a joint.