Figure 1
From: An additional muscle belly of the first lumbrical muscle
Right side palmar surface of the hand. 1, first lumbrical; 2, second lumbrical; 3, third lumbrical; 4, fourth lumbrical; CT, carpal tunnel; FDS, flexor digitorum superficialis tendon to the index finger; FR, flexor retinaculum; HE, hypothenar eminence; TE, thenar eminence. Note the 4-point star indicates the additional muscle belly of the first lumbrical muscle.