Henry Gray (18251861). Anatomy of the Human Body. 1918.
tubercle; it consists of an articular and a non-articular portion. The articular portion, the lower and more medial of the two, presents a small, oval surface for articulation with the end of the transverse process of the lower of the two vertebræ to which the head is connected. The non-articular portion is a rough elevation, and affords attachment to the ligament of the tubercle. The tubercle is much more prominent in the upper than in the lower ribs.
Body.The body or shaft is thin and flat, with two surfaces, an external and an internal; and two borders, a superior and an inferior. The external surface is convex, smooth, and marked, a little in front of the tubercle, by a prominent line, directed downward and lateralward; this gives attachment to a tendon of the Iliocostalis, and is called the angle. At this point the rib is bent in two directions, and at the same time twisted on its long axis. If the rib be laid upon its lower border, the portion of the body in front of the angle rests upon this border, while the portion behind the angle is bent medialward and at the same time tilted upward; as the result of the twisting, the external surface, behind the angle, looks downward, and in front of the angle, slightly upward. The distance between the angle and the tubercle is progressively greater from the second to the tenth ribs. The portion between the angle and the tubercle is rounded, rough, and irregular, and serves for the attachment of the Longissimus dorsi. The internal surface is concave, smooth, directed a little upward behind the angle, a little downward in front of it, and is marked by a ridge which commences at the lower extremity of the head; this ridge is strongly marked as far as the angle, and gradually becomes lost at the junction of the anterior and middle thirds of the bone. Between it and the inferior border is a groove, the costal groove, for the intercostal vessels and nerve. At the back part of the bone, this groove belongs to the