428 MUSCLES. 



unite, and are jointly inserted into the back of the base of the 

 third phalanx. 



The section of this muscle appropriated to the little finger 

 has a distinct appearance, and frequently its tendon goes through 

 a separate fossa in the radius, from which causes it has obtained 

 the name of Auricularis. A bursa invests these tendons at the 

 wrist as they pass through their groove, and is single above ; 

 but, in following the course of the tendons, like them it divides 

 and follows each tendon respectively to the base of the first 

 phalanx. 



This muscle extends all the joints of the fingers, being the 

 antagonist of the flexors.* 



6. TJte Supinalor Radii Brevis, 



Can only be well seen by detaching the origin of the afore- 

 said muscles; it will then be found in contact with the radius, 

 making a close investment of its head and upper third. It arises, 

 tendinous, from the external condyle of the os humeri, tendi- 

 nous and fleshy from the ridge on the posterior radial edge of 

 the ulna which descends from its coronoid process. 



Its fibres surround, obliquely, the upper external part of the 

 radius, and are inserted into its tubercle, and into its oblique 

 rough ridge, corresponding with the upper margin of the pro- 

 nator teres. At the interstice between the radius and ulna, near 

 the anterior edge of this muscle, a fleshy slip is occasionally 

 seen which passes from the radial side of the coronoid process 

 to the ulnar edge of the radius. 



This muscle rotates the radius outwards.f 



7. The Extensor Ossis Metacarpi Potticis Manns, 



Arises, fleshy, from the posterior part of the ulna immedi- 

 ately below the anconeus, from the interosseous ligament, and 



* Varieties. It sometimes sends a double tendon to the little finger, in which 

 case the auriculuris is more distinct than usual, and the tendon next to the ulna 

 runs through a distinct trochlea in the posterior carpal ligament. 



t Varieties. Sometimes the superior part is separated from the inferior; some 

 times the muscle is double.. 



