Abstract
Extraocular muscles are unique in both their cellular organization and constituent muscle fiber types. Aim of the work is to study the structure of the extraocular muscles in goat to recognize the subtypes of muscle fibers and their pattern of motor innervation. This study was carried on the extraocular muscles of goat (the recti and oblique muscles). Ten orbits taken from 5 goats immediately after slaughtering. The stem of oculomotor nerves III, IV and VI were studied for ranges of fiber-size distribution and the sensory pathway. Silver block impregnation to technique was used to study the structure and innervation of muscles. Semithin sections of the nerves III, IV and VI and specimens of muscles were blocked and stained by Toludine blue. By silver impregnation technique, each of the recti and oblique extraocular muscles are distinguished to two zones of muscle fibers: orbital zone (outer facing the bony orbit) and inner global zone (inner facing the globe). The orbital fibers are smaller than the global and they all stain black. The global fibers are larger and show grades of stain from red, intermediate to pale fibers. Within these zones different subtypes of muscle fibers have been identified varying in color, pattern of motor innervation, in structure, metabolism and contractile properties. We studied different types of muscle fiber found in the extraocular muscles. Control of eyeball movements depends on the complex structure and function of extraocular muscles.