is an inflammation of the tendon and synovial sheath, and puncture injuries cause infection of the synovial sheaths of the digits. The tendons of the second, third, and fourth digits have separate synovial sheaths so that the infection is confined to the infected digit, but
rupture of the proximal ends of these sheaths allows the infection to spread to the midpalmar
space. The synovial sheath of the little finger is usually continuous with the common synovial
sheath (ulnar bursa), and thus, tenosynovitis may spread to the common sheath and thus through
the palm and carpal tunnel to the forearm. Likewise, tenosynovitis in the thumb may spread through the synovial sheath of the flexor pollicis longus (radial bursa).