254 DETAILED SYNTHESIS. 



Muscles of the Upper Extremities. 



641. Remark. NEARLY ALL THE MUSCLES THUS FAR DESCRIBED may 

 assist in giving latitude of motion to the upper extremities : those that 

 act on the scapulae are especially to be classed with those of the arms. 



542. THE MUSCLES OF THE UPPER EXTREMITIES are 

 to be classed as those acting upon the shoulder-blades, 

 and moving it upon the chest and its fulcrum, the clavi- 

 cle; upon the upper arm, and moving it upon the scapula; 

 upon the lower arm, and moving it upon the humerus ; 

 acting upon the wrist, and moving it upon the lower arm ; 

 and upon the fingers, moving them upon their joints. 



543. SEVERAL MUSCLES EXTEND FROM THE SCAPU- 

 LA, and are attached to, the humerus, producing its 

 movements. 



544. THE BICEPS arises, as its name signifies, by 

 two heads from the scapulae, extends down the front of 

 the humerus, and is inserted in the radius, which, it will 

 be remembered, does not at all form the elbow-joint, be- 

 ing fastened to the ulna near the joint; but to its lower 

 end the wrist is jointed, and when the hand is to be 

 lifted it is better to have the biceps take hold of the 

 radius than of the ulna. (Fig. 6, PL 24.) 



545. THE TRICEPS arises from the scapula, extends 

 down the back of the humerus, and is inserted into the 

 point of the elbow. (Fig. 5, PI. 24.) 



546. THE USE OF THE BICEPS AND THE TRICEPS is to 

 raise and lower, or flex and extend, the forearm. 



547. THE MUSCLES OF THE FOREARM EXTEND, some 

 from one bone to the other, to roll the radius, and make 

 the hand prone or supine ; some to the wrist, to bend it 

 upon the arm ; and again others to the very finger-ends, 

 passing under a ligament like a bracelet, at the wrist, 

 provided with numerous bursaB to prevent friction. 



548. MUSCLES EXTEND FROM THE WRIST and from 



54X. What said of ? 642. How class ? 548. to what? 644. Describe * 

 646. Describe -. 646. What is-? 647. How do ? 648. How do-? 



