THE VESSELS AND NERVES. 25 



THE VESSELS AND NERVES. 



Coursing along in the subcutaneous areolar tissue, and therefore 

 just beneath the skin, are certain delicate tubes and cords called the 

 superficial vessels and nerves, which in the limbs are found resting 

 upon or outside the fascia, Fig. 6. The vessels are of two kinds : first, 

 the bloodvessels, which convey the blood, namely, the arteries, not here 

 represented, being comparatively small, and the veins, which are larger, 

 and are shown as dark meandering lines ; and, secondly, there are the 

 absorbent vessels, which convey a thin colorless fluid called lymph, and 

 which are exceedingly delicate, and can only be demonstrated by con- 

 summate skill and the aid" of mercurial injections: these absorbents 

 have little bodies connected with them at the bendings of the great 

 joints called the absorbent glands. The superficial nerves are delicate 

 white cords, shown in the figure as white lines; they are the cutaneous 

 'nerves, which perforate the fascia to reach the skin. 



When the fascia is removed, and the muscles dissected out, and some 

 of them cut away, the deep bloodvessels and nerves are brought into 

 view, taking their course in the intervals between the muscles. They 

 are connected by branches perforating the fascia with the superficial 

 sets. In Fig. 7, the main arteries of the upper limb are shown; the 

 veins are omitted for the sake of clearness ; the deep nerves, or mus- 

 cular nerves, belonging to the muscles, are exhibited ; the deep absorb- 

 ents are so delicate as to be quite undemonstrable in so small a figure. 



Such, then, are the parts to be found in the limbs, proceeding from 

 within outwards, viz., the bones containing their marrow, and covered 

 with the membranous periosteum ; the cartilages, ligaments, synovial 

 membranes, and synovia of the joints; the muscles with their tendons; 

 the intermuscular septa and areolar tissue, in which the deep absorb- 

 ents, bloodvessels, and nerves are found proceeding to and from the 

 muscles, bones, and joints; the fascia investing the muscles; the sub- 

 cutaneous areolar tissue and fat, containing the superficial bloodves- 

 sels, absorbents, and nerves belonging to the skin; and, lastly, the 

 skin itself. 



The very same parts are also found in the head, and in the general 

 framework of the trunk. But in these situations the skeleton not only 

 constitutes a central axis or basis for the surrounding muscles and 

 other soft parts, but some of its pieces are so shaped, arranged, and 

 held together as to inclose certain spaces or hollows, called the cavi- 

 ties of the body, in which those special parts of the system, called the 

 Organs or Viscera, are lodged and protected. 



THE CAVITIES OF THE BODY AND THEIR CONTAINED ORGANS. 



Three great Cavities are formed in the framework of the body, viz., 

 those of the Skull, the Chest, and the Abdomen. There is also a sub- 

 ordinate cavity within the spinal column, and several others in the 

 face. 



