SYSTEMATIC SYNTHESIS OF TISSUES INTO ORGANS. 249 



by its contractions it draws the blade downward and 

 forward. 



515. THE LATISSIMUS DORSI (broadest of the back) 

 extends from the back of the hips and the region of the 

 loins upward and outward to be attached to the arm, 

 and by contraction draws it down and backward. Its 

 tendon forms the back side of the armpit. (2, Fig. 1, 

 PL 22.) 



516. THE RHOMBOID has the shape its name signi- 

 fies, and extends from the upper part of the spinal col- 

 umn down and out to the back edge or base of the blade, 

 which it raises up and draws back. 



517. It therefore appears that THE SHOULDER-BLADE 

 is imbedded in muscles, by which it is suspended in its 

 place and moved in every direction, the use of it being 

 to furnish surface for the attachment of muscles to act 

 through it upon the shoulder and arm ; for the shoulder- 

 blade is never to be moved except to move the shoulder- 

 joint and extend the use of the arm. The blade lies 

 upon the chest, its position and projection being deter- 

 mined by the chest, but not affecting its form or size. 



518. Remark. MOST OF THE MUSCLES OF THE UPPER PART OF THE 

 TRUNK-WALLS AND OF THE NECK may assist in raising the ribs, as may be 

 noticed by drawing a deep breath. 



519. THE INTERCOSTALS, internal and external, are 

 two layers of fasciculi extending obliquely between the 

 ribs. By their oblique direction they are longer than if 

 direct, and if they contract one third their length, will 

 almost or quite bring the ribs together, while a contrac- 

 tion of one third their length, if direct, would only move 

 the ribs to an equal extent. (20, 21, Fig. 1, PI. 21.) 



520. AGAIN, IT is FOUND, WONDERFUL TO TELL, that 

 from their arrangement one set of these fasciculi raise 

 the ribs and the other depresses them, and neither can do 

 the work of the other. 



515. Describe . 516. Describe . 517. What said of ? Which effects the 

 other, the blade or chest ? 518. What said of ? 519. Describe ? 520. What ? 



11*. 



