The spinal nerves do not cross the median line in front except perhaps fine interlacing fibres.
In the Dorsal region the nerves are usually found following the interspaces until the lower ones debauch upon the abdominal wall anteriorly. There are, however, some Dorsal and lower Cervical nerve bundles which pass obliquely downward and outward to innervate back muscles.
Reference to the section on Spino-Organic Connection will make clear the tissues supplied by each nerve.
Slight deviations from the usual course of nerves are common; marked deviations very infrequent.
Use of Fingers
Use second finger of either hand for the palpating finger, choosing the hand which can be most conveniently used as determined by the position of patient and the part of the body to be examined. There is no set rule. Reinforce this second finger by the pressure upon it of the first and third and, if desired, by pressing thumb against it. (See [Fig. 5].)
Apply the tip of the palpating finger to the nerve with a motion such that it crosses the path of the nerve at right angles back and forth. Meanwhile the probable path of the nerve must be kept in mind. As the finger crosses the nerve-path it makes steady and even pressure upon any structures passing beneath it. The motion of the hand is almost a rolling motion, the finger tip probing, as it were, for a tender spot.
Tenderness—How Recognized
The irritated condition of the nerve which has thus been rolled beneath the finger may be recognized in one of three ways; the patient may involuntarily flinch, betraying the hurt; or he may inform the palpater of the hurt; or the swollen, cord-like nerve may be felt.