Both are freely used in all arm movements. Muscles of the outer arm are shown in Fig. 6.
F: Deltoid, the manner of its insertion shown on
Fig. 5-
H : Biceps, shows in both pronated and supinated positions and runs under the deltoid.
/ : Brachialis anticus, dividing triceps and biceps.
J : Triceps, showing on side and back, and greatly forming the outline of the arm.
K: Supinator longus, being a muscle that reaches far up into the upper arm, moving with the radius bone and forming important outlines.
L : Extensor carpi radialis longior.
M : Flexor carpi radialis.
A7.' Extensor carpi radialis brevior.
0 : Extensor communis digitorum.
P : Extensor carpi ulnaris.
X : Extensor ossis metacarpi pollicis.