CLAVICLE SCAPULA. 73 



the Central part, one for the head", and one for the tuberosity. The 

 two last have only one centre. 



Articulations. Each rib articulates with two vertebrae, and one 

 costal cartilage, with exception of the first, tenth, eleventh, and 

 twelfth, which articulate each* with a single vertebra only. 



Attachment of Muscles. To the ribs and their cartilages are at- 

 tached twenty -two pairs, and one single muscle. To the cartilages, 

 the subclavius, sterno-thyroid, pectoralis major, internal oblique, rec- 

 tus, transversalis, diaphragm, triangularis sterni, internal and exter- 

 nal intercostals. To the ribs, the intercostal muscles, scalenus 

 anticus, scalenus posticus, pectoralis minor, serratus magnus, obli- 

 quus externus, obliquus internus, latissimus dorsi, quadratus lumbo- 

 rum, serratus posticus superior, serratus posticus inferior, sacro- 

 lumbalis, longissimus dorsi, cervicalis ascendens, levatores costarum, 

 transversalis, and diaphragm. 



CLAVICLE. The clavicle is a long bone shaped somewhat like the 

 italic letter S, the convexity at one end being anterior and internal, 

 at the other posterior and external. The inner half of the bone is 

 rounded or irregularly quadrilateral, and terminates in a broad arti- 

 cular surface. The outer half is flattened from above downwards, 

 and broad at its extremity, the articular surface occupying only part 

 of its extent. The upper surface is smooth and convex, and partly 

 subcutaneous ; while the under surface is rough and depressed, for 

 the insertion of the subclavius muscle. At the sternal extremity of 

 the under surface is a very rough prominence, which gives attach- 

 ment to the rhomboid ligament ; and at the other extremity a rough 

 tubercle and ridge, for the coraco-clavicular ligament. The open- 

 ing -for the nutritious vessels is ^een upon the under surface of the 

 bone. 



Developement. By. two centres ; one for the shaft, and one for the 

 anterior prominence of the sternal extremity. 



Articulations. With the sternum and scapula. 



Attachment of Muscles. To six; the sterno-mastoid, trapezius, 

 pectoralis major, deltoid, subclavius, and sterno-hyoid. 



SCAPULA. The scapula is a flat triangular bone, situated upon the 

 posterior aspect and side of the thorax. It is divisible into an ante- 

 rior and posterior surface, superior, inferior, and posterior border, 

 anterior, superior, and inferior angle and processes. 

 The anterior surface, or -subscapular fossa, is concave and irregu- 

 lar, and marked by several oblique ridges. The whole concavity is 

 occupied by the subscapularis muscle, with the exception of a small 

 triangular portion near the superior angle. The posterior surface or 

 dorsum is convex, and unequally divided into two portions by the 

 spine ; that portion above the spine is the supra-spinous fossa,; and 

 that below, the infra-spinous fossa. 



The superior border is the shortest of the three ; it is thin and con- 

 cave, and terminated at one extremity by the superior angle, and at 

 the other by the coracoid process. At its inner termination, and 



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