Henry Gray (18251861). Anatomy of the Human Body. 1918.
Borders.The anterior border is concave, thin, and rough, and gives attachment to the Deltoideus. The posterior border is convex, rough, thicker than the anterior, and gives attachment to the Trapezius.
Medial Two-thirds.The medial two-thirds constitute the prismatic portion of the bone, which is curved so as to be convex in front, concave behind, and is marked by three borders, separating three surfaces.
Borders.The anterior border is continuous with the anterior margin of the flat portion. Its lateral part is smooth, and corresponds to the interval between the attachments of the Pectoralis major and Deltoideus; its medial part forms the lower boundary of an elliptical surface for the attachment of the clavicular portion of the Pectoralis major, and approaches the posterior border of the bone. The superior border is continuous with the posterior margin of the flat portion, and separates the anterior from the posterior surface. Smooth and rounded laterally, it becomes rough toward the medial third for the attachment of the Sternocleidomastoideus, and ends at the upper angle of the sternal extremity. The posterior or subclavian border separates the posterior from the inferior surface, and extends from the coracoid tuberosity to the costal tuberosity; it forms the posterior boundary of the groove for the Subclavius, and gives attachment to a layer of cervical fascia which envelops the Omohyoideus.
Surfaces.The anterior surface is included between the superior and anterior borders. Its lateral part looks upward, and is continuous with the superior surface of the flattened portion; it is smooth, convex, and nearly subcutaneous, being covered only by the Platysma. Medially it is divided by a narrow subcutaneous area into two parts: a lower, elliptical in form, and directed forward, for the attachment of the Pectoralis major; and an upper for the attachment of the Sternocleidomastoideus. The posterior or cervical surface is smooth, and looks backward toward the root of the neck. It is limited, above, by the superior border; below, by the subclavian border; medially, by the margin of the sternal extremity; and laterally, by the coracoid tuberosity. It is concave medio-laterally,