Henry Gray (18251861). Anatomy of the Human Body. 1918.
a zigzag line with a general convexity forward; when the arm is by the side the highest visible serration is that attached to the fifth rib.
The Deltoideus with the prominence of the upper end of the humerus produces the rounded contour of the shoulder; it is rounded and fuller in front than behind, where it presents a somewhat flattened form. Above, its anterior border presents a slightly curved eminence which forms the lateral boundary of the infraclavicular fossa; below, it is closely united with the Pectoralis major. Its posterior border is thin, flattened, and scarcely marked above, but is thicker and more prominent below. The insertion of Deltoideus is marked by a depression on the lateral side of the middle of the arm.
On the front and medial aspects of the arm is the prominence of the Biceps brachii, bounded on either side by an intermuscular depression. It determines the contour of the front of the arm and extends from the anterior axillary fold to the bend of the elbow; its upper tendons are concealed by the Pectoralis major and Deltoideus, and its lower tendon sinks into the anticubital fossa. When the muscle is fully contracted it presents a globular form, and the lacertus fibrosus attached