iv.] SKELE TON OF UPPER LIMB. 1 45 



LESSON IV. 



THE SKELETON OF THE UPPER LIMB. 



1. THE bones of man's upper limb are divisible into three 

 categories : A. Those of the shoulder ; B. Those of the arm ; 

 and C. Those of the hand. 



A. Those of the shoulder are the blade-bone, called the 

 scapula, and the collar-bone, called the clavicle* 



B. Those of the arm are subdivisible into (a] the upper 

 arm, and (b} the fore-arm. 



(a] In the upper arm there is but a single bone, called the 

 Jnnuenis. 



(//) In the fore-arm there are two long bones placed side 

 by side, and called the radius and the ulna. 



C. Those of the hand are divisible into the bones of the 

 wrist (or the carpus' 2 }, those of the middle, solid part of the 

 hand, called the metacarpus? and those of the fingers (or 

 digits), which are called phalanges* 



2. The SCAPULA is a flat, triangular bone, with three borders 

 and two surfaces. One of these surfaces is applied against 

 the ribs, and is concave. It is called the subscapular fossa. 

 The shortest of its three borders is uppermost. 



The other (dorsal or outer) surface is divided obliquely 

 into two unequal parts by a prominent ridge, called the 

 "spine," on which account the part above the ridge is termed 

 the supra-spinous fossa, and the part below it the infra- 

 spincus fossa. 



This spine becomes gradually more prominent from the 

 vertebral border of the scapula, while at its outer end it 

 expands into a large freely projecting process termed the 



1 davis, a key. 2 From Kapirnc. the wrist. 



3 From fiera, after, and Kaprr<$. 4 *Aa>f, anything set in array. 



