12 OUTLINES OF EQUINE ANATOMY. 



are generally spread out, forming layers, but sometimes, as 

 in the large intestine, are collected to form bands. When 

 in mass they are white in colour. Voluntary, striated, 

 or red muscular fibre is that which is under the control of 

 the will under ordinary circumstances. It consists pri- 

 marily of certain minute globular cells, sarcous elements, 

 which are arranged so as to form elongated chains or 

 jibrillcB. When examined under any but the highest 

 powers of the microscope the lines of junction of the cells 

 seem like black lines or stri(B extending across the fibrillse. 

 A number of fibrillae become collected into a bundle, sur- 

 rounded and connected together by a layer of simple mem- 

 brane, the sarcolemma, to form a fibre ; and the fibres are 

 collected into fasciculi, which vary in size, may be seen with 

 the naked eye, and are surrounded by perimysium. These 

 fasciculi are united together to form masses of various 

 shapes, red in colour, vulgarly known as "flesh." These 

 are the muscles of anatomists ; the study of them consti- 

 tutes myology. Muscles vary much in form, being in some 

 cases fusiform, in others flat, and in others irregular ; they 

 are attached to the basement structures in most cases, and 

 sometimes consist wholly of red muscular fibre, in others 

 the red muscular portion, belly, is continued by a white 

 ligamentous band, which may be cordiform, or expanded 

 and flat (aponeurotic). This band is termed a tendon; it 

 consists of dense, slightly modified, white fibrous tissue, and 

 in some places becomes firmly blended with the periosteum 

 of the bones to which it runs, in others becomes continuous 

 with ligaments. When the muscular fibres of a muscle 

 meet the tendon in a direction obliquely to its course on 

 one side the muscle is termed penniform ; if on both sides, 

 hijpenniform ; sometimes two fleshy bellies of a muscle are 

 connected by a central tendon, such a muscle is said to be 

 digastric. Muscles, as a rule, cover the surfaces of bones 

 and form grooves and channels through which the nerves 

 and blood-vessels pass, and as they are marked more or 

 less distinctly in different cases by prominences or depres- 

 sions on the surface of the body of the living animal, they 

 afford valuable surs^ical i^ruides. Vessels and nerves which 

 run in contact with a muscle are termed its satellites. The 

 muscles are extremely numerous, they vary in size from the 

 huge longissimus dorsi to the minute muscles of the middle 

 ear. The tendons of some muscles extend throughout 



