THE SCAPULA. 247 



in the following order : first, near the base of the acromion and in the root of the 

 coracoid process, the latter appearing in the form of a broad scale ; secondly, in 

 the inferior angle and contiguous part of the posterior border ; thirdly, near the 

 extremity of the acromion ; fourthly, in the posterior border. The acromion 

 process, besides being formed of two separate nuclei, has its base formed by an 

 extension into it of the centre of ossification which belongs to the spine, the 

 extent of which varies in different cases. The two separate nuclei unite, and 

 then join with the extension carried in from the spine. These various epiphyses 

 become joined to the bone between the ages of twenty-two and twenty-five years. 

 Sometimes failure of union between the acromion process and spine occurs, the 

 junction being effected by fibrous tissue or by an imperfect articulation; in some 

 cases of supposed fracture of the acromion with ligamentous union it is probable 

 that the detached segment was never united to the rest of the bone. Very often, 

 in addition to these, a minute epiphysis appears at the margin of the glenoid 

 cavity. 



Articulations. With the humerus and clavicle. 



Attachment of Muscles. To seventeen : to the anterior surface, the Subscapu- 

 laris : posterior surface. Supraspinatus. Infraspinatus ; spine, Trapezius. Deltoid ; 

 superior border. Omo-hyoid; vertebral border. Serratus magnus, Levator anguli 

 scapula?. Rhornboideus minor and major ; axillary border, Triceps, Teres minor. 

 Teres major: glenoid cavity, long head of the Biceps; coracoid process, short 

 head of the Biceps. Coraco-brachialis, Pectoralis minor ; and to the inferior angle 

 occasionally a few fibres of the Latissimus dorsi. 



Surface Form. The only parts of the scapula which are truly subcutaneous are the spine 

 and acrouiion process, but. in addition to these, the coracoid process, the internal or vertebral 

 border and inferior angle, and. to a less extent, the axillary border, may be defined. The acro- 

 mion process and spine of the scapula are easily felt throughout their entire length, forming, 

 with the clavicle, the arch of the shoulder. The acromion can be ascertained to be connected 

 to the clavicle at the acromio-clavicular joint by running the finger along it, its position being 

 often indicated by an irregularity or bony outgrowth from the clavicle close to the joint. The 

 acromion can be felt forming the point of the shoulder, and from this can be traced backward 

 to join the spine of the scapula. The place of junction is usually denoted by a prominence, 

 which is sometimes called the angle. From here the spine can be felt as a prominent ridge of 

 bone, marked on the surface as an oblique depression, which becomes less and less distinct, and 

 terminates a little external to the spinous processes of the vertebrae. Its termination is usually 

 indicated by a slitrbt dimple in the skin on a level with the interval between the third and fourth 

 dorsal spines. Below this point the vertebral border of the scapula may be traced, running 

 downward and outward, and thus diverging from the vertebral spines, to the inferior angle of 

 the bone, which can be recognized, although covered by the Latissimus dorsi muscle. From 

 this angle the axillary border can usually be traced through this thick muscular covering, form- 

 ing, with the muscles, the posterior fold of the axilla. The coracoid process may be felt about 

 an inch below the junction of the middle and outer third of the clavicle. Its position is indi- 

 cated on the surface of the body by a slight depression which corresponds to the interval 

 between the Pectoralis major and Deltoid muscles. When the arms are hanging by the side, 

 the upper angle of the scapula corresponds to the upper border of the second rib or the interval 

 between the first and second dorsal spines, the inferior angle to the upper border of the eighth 

 rib or the interval between the seventh and eighth dorsal spines. 



Surgical Anatomy. Fractures of the body of the scapula are rare, owing to the mobility 

 of the bone, the thick layer of muscles by which it is encased on both surfaces, and the elas- 

 ticity of the ribs on which it rests. Fracture of the neck of the bone is also uncommon. The 

 most frequent course of the fracture is from the suprascapular notch to the infraglenoid 

 tubercle, and it derives its principal interest from its simulation to a subglenoid dislocation of 

 the humerus. The diagnosis can be made by noting the alteration in the position of the 

 coracoid process. A fracture of the neck external to. and not including, the coracoid process is 

 saiil to occur, but it is exceedingly doubtful whether such an accident ever takes place. The 

 acromion process is more frequently broken than any other part of the bone, and there is some- 

 times, in young subjects, a separation of the epiphysis. It is believed that many of the cases 

 of supposed fracture of the acromion, with fibrous union, which have been found on post-mor- 

 tem examination are really cases of imperfectly united epiphysis. Sir Astley Cooper believed 

 that most fractures of this bone united by fibrous tissue, and the cause of this mode of union 

 was the difficulty there was in keeping the fractured ends in constant apposition. The coracoid 

 process is occasionally broken off, either from direct violence or perhaps, rarely, from muscular 

 action. 



Tumors of various kinds grow from the scapula. Of the innocent form of tumors prob- 

 ably the osteomata are the most common. When it grows from the venter of the scapula, as it 



