Henry Gray (18251861). Anatomy of the Human Body. 1918. arm, but
at the middle of the arm it diverges and descends to the back of
the medial epicondyle. In the forearm it is represented by a
line from the front of the medial epicondyle to the radial side
of the pisiform bone. The course of the radial nerve can be
indicated by a line from just below the posterior axillary fold,
to the lateral side of the humerus at the junction of its middle
and lower thirds; thence it passes vertically downward on the
front of the arm to the level of the lateral epicondyle. The
course of the superficial radial nerve is represented by a
continuation of this line downward to the junction of the middle
and lower thirds of the radial artery; it then crosses the
radius and runs distalward to the dorsum of the base of the
first metacarpal bone. The axillary nerve crosses the humerus
about 2 cm. above the center of a line joining the tip of the
acromion to the lower edge of the deltoid tuberosity. 13.
Surface Anatomy of the Lower Ex