Muscular disorders

Published

Book Section

© 2008 by Informa Healthcare USA, Inc. Most evaluations of muscle disease have been derived from the study of extremity muscles, which differ from extraocular muscles (EOMs). Before discussing muscle diseases that affect the eye, the structure of both extremity (limb) muscles and EOMs will be compared. A skeletal muscle, such as the biceps, consists of bundles (fasciculi) of individual muscle fibers with connective tissue surrounding each fasciculus (perimysium), and individual muscle fibers (endomysium) (Fig. 1). The contractile element of the muscle fiber is the myofibril, which is composed of essentially parallel arrays of actin and myosin filaments. Skeletal muscle is called striated muscle because of its banded microscopic appearance due to the A (anisotropic), I (isotropic), and Z (Zwischenscheibe) bands. The I band, which is pale when stained with hematoxylin and eosin, contains the actin filaments (5-8 nm in diameter), which are anchored at the thin, dense, Z band. The dark A band contains the thicker (15 nm in diameter) myosin filaments as well as actin filaments, which slide between the myosin filaments during contraction. The basic contractile unit of skeletal muscle is the sarcomere, which extends from Z band to Z band (Fig. 2).

Duke Authors

Cited Authors

  • Bossen, EH

Published Date

  • January 1, 2007

Book Title

  • Garner and Klintworth's Pathobiology of Ocular Disease Part B, Third Edition

Start / End Page

  • 1531 - 1566

International Standard Book Number 10 (ISBN-10)

  • 142007976X

International Standard Book Number 13 (ISBN-13)

  • 9781420079760

Citation Source

  • Scopus