THE MUSCLES. 125 



rior of cavities (chest and abdomen), expanded in a manner resembling and 

 between membranes, without tendons and antagonist muscles. They are not 

 under the influence of the will. To this class belong: the muscular coats of 

 the intestines and excretory ducts ; and the fibres of the heart which, how- 

 ever, belong to it, only in relation to their involuntary movement. 



2. According to their actions we distinguish 



. Antagonising muscles, antagonists; for example, flexor and extensor 

 muscles. 



&. Associatsrl, sorcz, which act simultaneously to produce a certain effect. 



y. Flexors, fiexores, and Extensors^ extensores. 



J. Ab- arid Adductors, ab- and addudores, which remove parts from, or 

 bring them to, the middle line of the body. 



j. Rotators, rotatores, which roll a part upon its axis, inwards (pronatores) or 

 outwards (supinatores). 



3. According to their shape, voluntary muscles are distinguished, as 



a.. Long muscles, which arise either with one, two, or several heads or 

 dentations from a fixed point, form one or more thick central portions 

 (belly), and are attached either with a single or divided ends (tail) to the 

 moveable point. 



B. Flat, broad muscles, are thin, tri- or quadrangular, like a membrane, lie 

 on the parietes of cavities, arid terminate with Aponeuroses 5 e. g., the abdo- 

 minal muscles. 



y. Closing, circular muscles, rphincleres, with circular, encompassing primi- 

 tive fibres, lying round about natural openings; e. g., Sphincter Ani. 



We likewise find, among the class of involuntary muscles, layers of longi- 

 tudinal and circular fibres, with others, crossing each other in various ways 

 (hollow muscles). 



146. e. Auxiliary organs of muscles. 



1. Tendons. Their fibres are not continuations of the mus- 

 cular, but are only embraced by them, so that the two are sepa- 

 rated by boiling; even the capillary vessels of the muscles do 

 not pass into them. Sinews, (endines, are the cord-like tendons 

 which form the prolongations of the muscles, and often extend to 

 considerable length. When the muscular fibres are continued 

 upon both sides, the so-called penniform muscles arise, when only 

 on one side the semi-pennifonn. 



a. Aponeuroses are flat expansions of the tendons, which occur with flat 

 muscles, and which are generally united, as they lie on the same plane, e. g., 

 on the skull. 



b. Fascia (also called aponeuroses), tendinous envelopes for the muscles, 

 summn:!i:ig an I isolating separate muscles and groups of muscles, maintain- 

 ing them in their situation, and even serving for their attachment, since they 

 send ofi; in many places, processes to the bones (ligg. intermuscularia) ; also 

 t'li- .-inews with peculiarly long sheaths (vagina) tendinium librosu-). or pro- 

 \ i led with narrow restraining bands (ret macula), to prevent displacement. 



Fafcia superficialis is such an envelope, which lies close beneath the 

 coriuin, and surroun Is all superficial muscles. It consists of fibrous laminae 

 crowing each other, and iut;:rwoven with elastic fibres, between which lie fat, 

 superficial nji VL-S and vessels. 



