THE BONES OF THE UPPER EXTREMITY 77 



The number of ribs may be thirteen on one or both sides. 

 The added rib is most often connected with the first lumbar 

 transverse process, sometimes with the seventh cervical verte- 

 bra, where it has a double attachment, viz., to the body and 

 to the transverse process. The twelfth rib varies in length 

 from 8 inches to less than 1 inch. 



The Costal Cartilages 



The costal cartilages prolong the ribs to the sternum. Their 

 breadth diminishes from the first to the last; they become 

 narrow toward their sternal extremities; their length increases 

 to the seventh; the first descends a little, the second is hori- 

 zontal, the others, except the last two, ascend after following 

 the direction of the rib for a short distance. Their external 

 extremities are convex, and planted into the osseous tissue 

 of corresponding ribs. The inner extremity of the first is 

 united directly to the sternum without articular cavity; the 

 succeeding six have rounded extremities for the sternal notches. 

 Each cartilage of the first three false ribs is united to the lower 

 border of the one above it. The fifth, sixth, seventh, and 

 eighth cartilages articulate with each other; the eleventh 

 and twelfth are pointed and unattached. 



They give partial attachment to the diaphragm, internal 

 abdominal, oblique, transversalis, rectus, triangularis sterni, 

 internal intercostals, pectoralis major, subclavian, and sterno- 

 thyroid muscles. 



The eighth may articulate with the sternum. The seventh 

 may meet its fellow of the other side in front of the ensiform. 

 There may be no articulation between the fifth and sixth; 

 theretmay be one between the eighth and ninth. 



THE BONES OF THE UPPER EXTREMITY 



Upper limb 



Shoulder -I L, forming shoulder girdle. 



Arm (brachium), humerus. 



Forearm (antebrachium), radius and ulna. 



[ carpus. 

 Hand (manus) < metacarpus. 



[ phalanges. 



