THE MUSCLES AND FASCIA. 1 



fTlHE Muscles are connected with the bones, cartilages, ligaments, and skin, 

 _L either directly or through the intervention of fibrous structures called tendons 

 or aponeuroses. Where a muscle is attached to bone or cartilage, the fibres ter- 

 minate in blunt extremities upon the periosteum or perichondrium, and do not 

 come into direct relation with the osseous or cartilaginous tissue. Where muscles 

 are connected with the skin, they either lie as a flattened layer beneath it, or are 

 connected with its areolar tissue by larger or smaller bundles of fibres, as in the 

 muscles of the face. 



The muscles vary extremely in their form. In the limbs, they are of consid- 

 erable length, especially the more superficial ones, the deep ones being generally 

 broad ; they surround the bones and form an important protection to the various 

 joints. In the trunk they are broad, flattened, and expanded, forming the parietes 

 of the cavities which they enclose ; hence the reason of the terms, long, broad, 

 short, etc., used in the description of a muscle. 



There is a considerable variation in the arrangement of the fibres of certain 

 muscles with reference to the tendons to which they are attached. In some, the 

 fibres are parallel and run directly from their origin to their insertion ; these are 

 quadrilateral muscles, such as the Thyro-hyoid. A modification of these is found 

 in the fusiform muscles, in which the fibres are not quite parallel, but slightly 

 curved, so that the muscle tapers at each end ; in their action, however, they 

 resemble the quadrilateral muscles. Secondly, in other muscles the fibres are 

 convergent ; arising by a broad origin, they converge to a narrow or pointed 

 insertion. This arrangement of fibres is found in the triangular muscles e. g. the 

 Temporal. In some muscles, which otherwise would belong to the quadrilateral 

 or triangular type, the origin and insertion are not in the same plane, but the plane 

 of the line of origin intersects that of their insertion ; such is the case in the 

 Pectineus muscle. Thirdly, in some muscles the fibres are oblique and converge, 

 like the plumes of a pen, to one side of a tendon, which runs the entire length of 

 the muscle. Such a muscle is rhomboidal or penniform, as the Peronei. A 

 modification of these rhomboidal muscles is found in those cases where oblique fibres 

 converge to both sides of a central tendon which runs down the middle of the 

 muscle ; these are called bipenniform, and an example is afforded in the Rectus 

 femoris. Finally, we have muscles in which the fibres are arranged in curved 

 bundles in one or more planes, as in the Sphincter muscles. The arrangement of 

 the muscular fibres is of considerable importance in respect to their relative 

 strength and range of movement. Those muscles where the fibres are long and 

 few in number have great range, but diminished strength ; where, on the other 

 hand, the fibres are short and more numerous, there is great power, but lessened 

 range. 



Muscles differ much in size : the Gastrocnemius forms the chief bulk of the 

 back of the leg, and the fibres of the Sartorius are nearly two feet in length, whilst 



1 The Muscles and Fasciae are described conjointly, in order that the student may consider the 

 arrangement of the latter in his dissection of the former. It is rare for the student of anatomy in this 

 country to have the opportunity of dissecting the fasciae separately ; and it is for this reason^ as well 

 as from the close connection that exists between the muscles and their investing sheaths, that they are 

 considered together. Some general observations are first made on the anatomy of the muscles and 

 fasciae, the special description being given in connection with the different regions. 



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