50. The place where the kidney is most accessible to pressure is below the last rib, on the outer edge of the erector spinæ.
51. The highest part of the ilium is about the level of the fourth lumbar spine. The best incision for opening the descending colon is in a slightly sloping line beginning at the outer edge of the erector spinæ, midway between the crest of the ilium and the last rib, and continued across the flank for three inches or more, according to the amount of subcutaneous fat.
52. In the pit of the neck we can feel the trapezius and the ligamentum nuchæ. By pressing deeply we detect the forked and prominent spine of the second cervical vertebra.
53. The spines of the third, fourth, and fifth cervical vertebræ recede from the surface to permit free extension of the neck, and cannot often be felt. But the spines of the sixth and seventh (v. prominens) stand out well.
54. Notice that most of the spines of the dorsal vertebræ, owing to their obliquity, do not tally with the heads of their corresponding ribs. Thus, the spine of the second dorsal corresponds with the head of the third rib; the spine of the third dorsal with the head of the fourth rib, and so on till we come to the eleventh and twelfth dorsal vertebræ, which do tally with their corresponding ribs. All this, however, is best seen in the skeleton.
55. The spines of the vertebræ may be useful as landmarks indicative of the levels of important organs. I have therefore arranged them in a tabular form, thus:—
Tabular Plan of Parts opposite the Spines of the Vertebræ.
| Cervical. | 5th. | Cricoid cartilage. Œsophagus begins. |
| 7th. | Apex of lung: higher in the female than in the male. ([30]) | |
| Dorsal. | 1st. | |
| 2nd. | ||
| 3rd. | Aorta reaches spine. Apex of lower lobe of lung. Angle of bifurcation of trachea. ([49]) | |
| 4th. | Aortic arch ends. Upper level of heart. | |
| 5th. | ||
| 6th. | ||
| 7th. | ||
| 8th. | Lower level of heart. Central tendon of diaphragm. | |
| 9th. | Œsophagus and vena cava through diaphragm. Upper edge of spleen. | |
| 10th. | Lower edge of lung. Liver comes to surface posteriorly. Cardiac orifice of stomach. | |
| 11th. | Lower border of spleen. Renal capsule. | |
| 12th. | Lowest part of pleura. Aorta through diaphragm. Pylorus. | |
| Lumbar. | 1st. | Renal arteries. Pelvis of kidney. ([83]) |
| 2nd. | Termination of spinal cord. Pancreas. Duodenum just below. Receptaculum chyli. | |
| 3rd. | Umbilicus. Lower border of kidney. | |
| 4th. | Division of aorta. ([65]) Highest part of ilium. | |
| 5th. |
56. Origins of the spinal nerves.—It is useful to know opposite what vertebræ the spinal nerves in the different regions arise from the spinal cord. They arise as follows:—
The origins of the eight cervical nerves correspond to the interval between the occiput and the sixth cervical spine.