Motor nerve endings in extraocular muscles

Abstract In rat extraocular muscles, “en plaque” motor endings with subsynaptic folds were mainly localized at the terminal innervation band, and were present singly in muscle fibers having “Fidrillenstrucktur” and diameters of 18 to 30 μ. The “en grappe” motor endings without subsynaptic folds were found in the proximal and distal thirds of four rectus and two oblique muscles, and 10 to 16 endings were present in muscle fibers having “Felderstruktur” and diameters of 6 to 13 μ. The mean diameter of “en plaque” endings was 31.5 μ in the levator palpebrae and 32.1 μ in the rectus superior, which is larger compared with 27.1 μ in the tibialis anterior. The mean diameter of “en grappe” endings of the superior rectus muscle was 10.0 μ. The mean diameter of muscle fibers was 18.2 μ in the levator palpebrae, 18.5 μ in the superior rectus, and 33.1 μ in the tibialis anterior.