153. What is meant by the origin of a muscle? The insertion? The swell? What is the color of muscles? With what is each muscular fibre supplied? 154. What is said of fascia? What is its appearance when freshly exposed? 155. What effect has it on the muscles? Give other uses of the fascia.
156. The interstices between the different muscles are filled with adipose matter, or fat. This is sometimes called the packing of the system. To the presence of this tissue, youth are indebted for the roundness and beauty of their limbs.
Fig. 37.
Fig. 37. A transverse section of the neck. The separate muscles, as they are arranged in layers, with their investing fasciæ, are beautifully represented. As the system is symmetrical, figures are placed only on one side. In the trunk the muscles are arranged in layers, surrounded by fasciæ, as in the neck. The same is true of the muscles of the upper and lower limbs.
12, The trachea, (windpipe.) 13, The œsophagus, (gullet.) 14, The carotid artery and jugular vein. 28, One of the bones of the spinal column. The figures that are placed in the white spaces represent some of the fasciæ; the other figures indicate muscles.
157. The muscles may be arranged, in conformity with the general division of the body, into four parts: 1st. Those of the Head and Neck. 2d. Those of the Trunk. 3d. Those of the Upper Extremities. 4th. Those of the Lower Extremities.
156. Give a reason why the limbs of youth are rounder than those of the aged. Describe fig. 37.