56 ANATOMY FOR NURSES. [CHAP. VI. 



nuclei multiply, so that each cell is converted into a long, multi-nucleated 

 protoplasmic fibre. At first the substance of the fibre is not striated, but 

 presently it becomes longitudinally striated along one side, and about the 

 same time a delicate membrane, the sarcolemma, may be discovered bound- 

 ing the fibre; then transverse striation commences, and gradually extends 

 around the fibre, and, finally, the nuclei take up their position under the 

 sarcolemma. 



Regeneration of muscular tissue. It was formerly thought that after 

 removal, by the knife, or by disease, muscular tissue was not regenerated, 

 but that any breach of continuity which might occur in the muscle was filled 

 up by a growth of connective tissue. It would appear, however, that the 

 breach is after a certain lapse of time bridged across by muscular substance, 

 but how the new muscular tissue is formed is not fully understood. 



Attachment of muscles to the skeleton. The muscles are sepa- 

 rate organs, each muscle having its own sheath of connective 

 tissue. The connective tissue extends also into the muscle, form- 

 ing sheaths for the smaller bundles, connecting and binding the 

 fibres and bundles together, and conducting and supporting the 

 blood-vessels and nerves distributed to the muscle fibres. 



The muscles vary greatly in shape and size. In the limbs 

 they are of considerable length, forming more or less elongated 

 straps ; in the trunk they are broad, flattened, and expanded, 

 forming the walls of the cavities which they enclose. 



They are attached to the bones, cartilages, ligaments, and 

 skin in various ways, the most common mode of attachment 

 being by means of tendons. The muscular fibres converge as 

 they approach their tendinous extremities, and gradually blend 

 with the fibres of the tendons, the tendons in their turn insert- 

 ing their fibres into the bones. Sometimes the muscles end in 

 expanded form in the* flat fibrous membranes, called aponeuroses. 

 Again, in some cases, the muscles are connected with the bones, 

 cartilages, and skin, without the intervention of tendons or 

 aponeuroses. 



In the description of muscles it is customary to speak of the 

 attachments of their opposite ends under the names of origin 

 and insertion, the first term being usually applied to the 

 more fixed attachment, and the second to the more movable 

 attachment. 



The muscular tissue or flesh forms a large proportion of the 

 weight of the whole body. The following has been calculated 

 for a man of one hundred and fifty pounds' weight from the 



