74 BONES OF THE UPPEK LIMB. 



(For an account of the varieties of form thus produced, see Virchow, " Gesammelte 

 Abhandlungen," 1856.) Another series of irregular forms of skull is that produced 

 by pressure artificially applied in early life, and is best exemplified from among 

 those American tribes who compress the heads of their children by means of an 

 apparatus of boards and bandages : it is also illustrated in a slighter degree by 

 individual instances in which undue pressure has been employed unintentionally. 

 (Gosse, "Essai. BUT les Deformations artificielles du Crane," 1855.) Posthumous 

 distortions likewise occur in long-buried skulls, subjected to the combined influence 

 of pressure and moisture. (Wilson, " Prehistoric Annals of Scotland.") 



IV. BONES OF THE UPPER LIMB. 



The superior extremity, or upper limb, consists of the shoulder, the arm, 

 the fore arm, and the hand. The bones of the shoulder are the scapula and 

 clavicle ; in the arm is the humerus ; in the fore arm are the radius and 

 ulna ; and ID the hand three groups of bones, the carpus, metacarpus, and 

 digital phalanges, 



SCAPULA. 



This bone is placed upon the upper and back part of the thorax, occupies 

 the space from the second to the seventh rib, and forms the posterior part of 

 the shoulder. 



It is attached directly to the trunk only by the clavicle, and from it is 

 suspended the humerus. 



It is of an irregular triangular form, flat in the greater part of its extent, 

 and elongated downwards ; and is so placed, that its internal border is like- 

 wise posterior. Its angles may be termed superior, inferior, and external. 



It has an anterior and posterior surface, and presents at its external 

 angle the head with its glenoid cavity or articular surface for the humerus, 

 supported on a short thick neck of bone, and surmounted by the coracoid 

 process ; also, springing from its posterior surface, the spine terminating in 

 the acromion process. 



The anterior surface exhibits in the greater part of its extent a shallow 

 concavity, the fossa subscapularis or venter, occupied by the subscapularis 

 muscle, and marked by irregular prominent lines converging upwards and 

 outwards, which give attachment to the tendinous intersections of that 

 muscle. Separated, however, from this concavity, there are several smaller 

 flat spaces : one is a triangular surface in front of the superior angle, 

 another is a smaller surface at the inferior angle, and these, together with a 

 rough line running close to the posterior border and uniting them, give 

 attachment to the serratus magnus muscle : there is also a grooved area 

 occupied by the lower border of the subscapularis muscle, close to the ex- 

 ternal border, and separated from the fossa subscapularis by a prominent 

 ridge descending from the neck of the bone. 



The posterior surface or dorsum is divided by the spine into two unequal 

 parts, the superior and smaller of which is called fossa supraspinata, the in- 

 ferior fossa infraspinata. The supraspinous fossa has its greatest vertical 

 extent at its internal extremity, but is deepest externally : it is occupied by 

 the supra-spinatus muscle. The infraspinous fossa, much larger than the 

 preceding, presents in the middle a convexity corresponding to the concavity 

 of the venter, and outside this a concavity bounded by the prominent 

 external border. It is marked near the inner border by short lines, cor- 

 responding to tendinous septa of the infraspinatus muscle, and is occupied 

 by that muscle in the greater part of its extent. Adjacent to the external 

 border, in its middle third, is a narrow inteival giving attachment to the 



