The ribs which require especial consideration are five in number-viz. the first, second, tenth, eleventh and twelfth.
The first rib is one of the shortest and the most curved of all the ribs; it is broad and flat, its surfaces looking upward and downward, and its borders inward and outward. The head is of small size, rounded, and presents only a single articular facet for articulation with the body of the first dorsal vertebra. The neck is narrow and rounded. The tuberosity, thick and prominent, rests on the outer border. There is no angle, but in this situation the rib is slightly bent, with the convexity of the bend upward, so that the head of the bone is directed downward. The upper surface of the shaft is marked by two shallow depressions, separated by a small rough surface for the attachment of the Scalenus anticus muscle-the groove in front of it transmitting the subclavian vein, that behind it the subclavian artery. Between the groove for the subclavian artery and the tuberosity is a rough surface, for the attachment of the Scalenus medius muscle. The under surface is smooth, and destitute of the groove observed on the other ribs. The outer border is convex, thick, and rounded, and at its posterior part gives attachment to the first serration of the Serratus magnus; the inner is concave, thin, and sharp, and marked about its centre by the commencement of the rough surface for the Scalenus anticus. The anterior extremity is larger and thicker than any of the other rib".The second rib is much longer than the first. but bears a very considerable resemblance to it in the direction of its curvature. The non-articular portion of the tuberosity is occasionally only slightly marked. '1'he angle is slight and situated close to the tuberosity, and the shaft is not twisted, so that both ends touch any plane surface upon which it may be laid; but there is a similar though slighter bend, with its convexity upward. to that found in the first rib. The shaft is not horizontal, like that of the first rib, its outer surface, which is convex, looking upward and a little outward. It presents, near the middle, a rough eminence for the attachment of the second and third digitations of the Serratus magnus; behind and above which is attached the Scalenus posticus.
The first rib is one of the shortest and the most curved of all the ribs; it is broad and flat, its surfaces looking upward and downward, and its borders inward and outward. The head is of small size, rounded, and presents only a single articular facet for articulation with the body of the first dorsal vertebra. The neck is narrow and rounded. The tuberosity, thick and prominent, rests on the outer border. There is no angle, but in this situation the rib is slightly bent, with the convexity of the bend upward, so that the head of the bone is directed downward. The upper surface of the shaft is marked by two shallow depressions, separated by a small rough surface for the attachment of the Scalenus anticus muscle-the groove in front of it transmitting the subclavian vein, that behind it the subclavian artery. Between the groove for the subclavian artery and the tuberosity is a rough surface, for the attachment of the Scalenus medius muscle. The under surface is smooth, and destitute of the groove observed on the other ribs. The outer border is convex, thick, and rounded, and at its posterior part gives attachment to the first serration of the Serratus magnus; the inner is concave, thin, and sharp, and marked about its centre by the commencement of the rough surface for the Scalenus anticus. The anterior extremity is larger and thicker than any of the other rib".The second rib is much longer than the first. but bears a very considerable resemblance to it in the direction of its curvature. The non-articular portion of the tuberosity is occasionally only slightly marked. '1'he angle is slight and situated close to the tuberosity, and the shaft is not twisted, so that both ends touch any plane surface upon which it may be laid; but there is a similar though slighter bend, with its convexity upward. to that found in the first rib. The shaft is not horizontal, like that of the first rib, its outer surface, which is convex, looking upward and a little outward. It presents, near the middle, a rough eminence for the attachment of the second and third digitations of the Serratus magnus; behind and above which is attached the Scalenus posticus.
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