Chap. V] 



THE SKELETON 



71 



-Head 



-Lesser tuberosity 



-Surgical neck 



the clavicle is generally less curved, smoother, shorter, and more 

 slender than in the male. In those persons who perform consider- 

 able manual labor, which brings into constant action the muscles 

 connected with this bone, it acquires considerable bulk. 



Scapula, or shoulder blade. — It is a large, flat bone, triangular 

 in shape, placed between the second and seventh, or sometimes 

 eighth, ribs on the back part of the thorax. It is unevenly divided 

 on its dorsal surface by a very prominent ridge, the spine of the 

 scapula, which termi- 

 nates in a large triangU- Anatomical neck. 



lar projection called the Greater tuberosity- 

 acromion process, or 

 summit of the shoulder. 

 Below the acromion pro- 

 cess, at the head of the 

 shoulder blade, is a shal- 

 low socket, the glenoid 

 cavity, which receives 

 the head of the humerus. 

 Humerus, or arm 

 bone. — The humerus 

 is the longest and largest 

 bone of the upper limb. 

 The upper extremity of 

 the bone consists of a 

 rounded head joined to 

 the shaft by a con- 

 stricted neck, and' of two 

 eminences called the 

 larger and smaller tu- 

 bercles, also known as 

 tuberosities. The head 

 articulates with the gle- 

 noid cavity of the scap- 

 ula. The constricted neck above the tubercles is called the 

 anatomical neck, and that below the tubercles, the surgical 

 neck, because it is so often fractured. The lower extremity of 

 the bone is flattened from before backward into a broad articular 

 surface called the trochlea which is divided by a slight ridge so 



■ Trochlea 



Condyles 



Fig. 50. — The Left Humerus, or Arm Bone. 

 (Morrow.) 



