86 



DISSECTION OF THE BACK OF THE FOREARM. 



on elbow 

 and wrist. 



Extensor of 

 little finger : 



origin ; 



The digits being straightened, it will assist the other muscles in 

 extending the wrist and the elbow. 



The EXTENSOR MINIMI DIGITI (E) is the most slender muscle on 

 ^ ne k ac k o f the forearm, and appears to be but a part of the common 

 extensor. Its origin is in common with that of the extensor com- 

 munis, but it passes through a distinct sheath of the annular liga- 

 termination; ment. Beyond the ligament the tendon splits into two, and the j 

 outer part is joined by the fourth tendon of the common extensor : 

 finally, both parts enter the common expansion on the first phalanx 

 of the little finger. 



Triceps. 



Supinator brevis. 



Pronator teres. 



Extensor brevis pollicis. 



Extensor carpi ulnaris. 

 Flexor carpi ulnaris. 



Flexor profundus digitorum. 



Extensor longus pollicis. 

 Flexor carpi ulnaris. 



Extensor indicis. 



FIG. 36. THE RADIUS AND ULNA FROM BEHIND. 



and use. Action. It extends the little finger and moves back the wrist 



and elbow. As the inner piece of the split tendon is not united 

 with the common extensor, it can straighten the digit during flexion 

 of the other fingers. 



The EXTENSOR CARPI ULNARIS MUSCLE (F) arises from the com- 

 mon tendon, the aponeurosis of the forearm, and an intermuscular 

 septum on its outer side ; it is also fixed by fascia to the middle 

 third of the posterior border of the ulna below the anconeus 

 muscle (fig. 36). Its tendon becomes free from fleshy fibres near 

 the annular ligament, and passes through a separate sheath in that 



insertion ; structure to be inserted into the tuberosity at the base of the 

 metacarpal bone of the little finger. 



Extensor 

 carpi ulna- 

 ris: 



origin ; 



