296 THE MUSCLES AND FASCIA. 



the Stapedius, a small muscle of the internal ear, weighs about a grain, and its 

 fibres are not more than two lines in length. 



The names applied to the various muscles have been derived 1, from their 

 situation, as the Tibialis, Radialis, Ulnaris, Peroneus ; 2, from their direction, as 

 the Rectus abdominis, Obliqui capitis, Transversalis ; 3, from their uses, as Flexors, 

 Extensors, Abductors, etc. ; 4, from their shape, as the Deltoid, Trapezius, Rhom- 

 boideus ; 5, from the number of their divisions, as the Biceps, the Triceps ; 6, 

 from their points of attachment, as the Sterno-cleido-mastoid, Sterno-hyoid, 

 Sterno-thyroid. 



In the description of a muscle the term origin is meant to imply its more fixed 

 or central attachment, and the term insertion, the movable point to which the 

 force of the muscle is directed ; but the origin is absolutely fixed in only a very 

 small number of muscles, such as those of the face, which are attached by one 

 extremity to the bone and by the other to the movable integument; in the greater 

 number the muscle can be made to act from either extremity. 



In the dissection of the muscles the student should pay especial attention to 

 the exact origin, insertion, and actions of each, and its more important relations 

 with surrounding parts. An accurate knowledge of the points of attachment of 

 the muscles is of great importance in the determination of their action. By a 

 knowledge of the action of the muscles the surgeon is able to explain the causes 

 of displacement in various forms of fracture and the causes which produce 

 distortion in various deformities, and, consequently, to adopt appropriate treat- 

 ment in each case. The relations, also, of some of the muscles, especially those in 

 immediate apposition with the larger blood-vessels, and the surface-markings they 

 produce, should be especially remembered, as they form useful guides in the 

 application of a ligature to those vessels. 



Tendons are white, glistening, fibrous cords, varying in length and thickness, 

 sometimes round, sometimes flattened, of considerable strength, and devoid of 

 elasticity. They consist almost entirely of white fibrous tissue, the fibrils of 

 which have an undulating course parallel with each other and are firmly united 

 together. They are very sparingly supplied with blood-vessels, the smaller 

 tendons presenting in their interior not a trace of them. Nerves also are not 

 present in the smaller tendons, but the larger ones, as the tendo Achillis, receive 

 nerves which accompany the nutrient vessels. The tendons consist principally of 

 a substance which yields gelatin. 



Aponeuroses are flattened or ribbon-shaped tendons, of a pearly-white color, 

 iridescent, glistening, and similar in structure to the tendons. They are destitute 

 of nerves, and the thicker ones only sparingly supplied with blood-vessels. 



The tendons and aponeuroses are connected, on the one hand, with the muscles, 

 and, on the other hand, with the movable structures, as the bones, cartilages, 

 ligaments, fibrous membranes (for instance, the sclerotic). Where the muscular 

 fibres are in a direct line with those of the tendon or aponeurosis, the two 

 are directly continuous, the muscular fibre being distinguishable from that 

 of the tendon only by its striation. But where the muscular fibre joins the 

 tendon or aponeurosis at an oblique angle the former terminates, according 

 to Kolliker, in rounded extremities, which are received into corresponding depres- 

 sions on the surface of the latter, the connective tissue between the fibres 

 being continuous with that of the tendon. The latter mode of attachment 

 occurs in all the penniform and bipenniform muscles, and in those muscles 

 the tendons of which commence in a membranous form, as the Gastrocnemius 

 and Soleus. 



The fasciae (fascia, a bandage) are fibrp-areolar or aponeurotic laminae of 

 variable thickness and strength, found in all regions of the body, investing the 

 softer and more delicate organs. The fasciae have been subdivided, from the 

 situation in which they are found, into two groups, superficial and deep. 



The superficial fascia is found immediately beneath the integument over almost 

 the entire surface of the body. It connects the skin with the deep or aponeurotic 



