426 MUSCLES. 



joint; and terminates about the middle of the radius in a flat 

 tendon. 



Itjis inserted, by the tendon, into a small, rough ridge, on 

 the outer side of the radius just above its styloid process. 



It rolls the radius outwards. 



2. The Extensor Carpi Radialis Longior, 



Is situated beneath the former muscle. It arises, tendinous 

 and fleshy, from the space of the external ridge of the os hu- 

 meri, between the supinator longus and the external condyle. 

 It forms a short, fleshy belly, which terminates in a flat tendon 

 above the middle of the radius. 



It is inserted, by this tendon, into the posterior part of the 

 root of the metacarpal bone of the fore finger, near the thumb. 



The tendon of this muscle is surrounded by a synovial sheath, 

 at the place where it passes the lower end of the radius, under 

 the posterior carpal ligament. Another bursa exists, also, at 

 its insertion; which, on one occasion, I found so much enlarged 

 in a young woman, as to require its extirpation: the operation 

 was fully successful. 



It extends the hand.* 



3. The Extensor Carpi Radialis Brevior, 



Is beneath the last, but projects somewhat beyond it. It 

 arises, tendinous, from the posterior and lower part of the ex- 

 rernal condyle, and from the external lateral ligament of the 

 elbow joint. It forms a thick, fleshy belly, placed along the 

 radius, and terminates in a flat tendon about the middle of that 

 bone. 



Its tendon, becoming rounded, is inserted into the posterior 

 part of the base of the metacarpal bone of the second finger, 

 and has a bursa beneath its insertion, and another at the. wrist. 



It extends the hand.f 



* Varieties. Sometimes a small fasciculus is detached from its posterior mar- 

 gin, and has a tendinous insertion into the third metacarpal bone. 



t Varieties. Sometimes this muscle is so blended with the preceding, as to be 

 *n common with it. 



