264 



DISSECTION OF THE FRONT OF THE FOREARM. 



80. MUSCLES ON THE FRONT OF THE FOREARM (fig. 



HO). The muscles on the front of the forearm are 

 divided into a superficial and a deep layer. 



'"iHilS-H In the superficial layer there are five muscles, 



which are fixed to the inner condyle of the hu- 

 merus, mostly by a common tendon, and lie in the 

 undermentioned order from the middle to the inner 

 side of the limb : pronator radii teres, flexor carpi 

 radialis, palmaris longus, flexor carpi ulnaris ; and 

 deeper and larger than any of these is the flexor 

 sublimis digitorum. 



The deep layer will be met with in a subsequent 

 dissection (p. 270). 



The PRONATOR RADII TERES (fig. 80, 3 ) arises 

 from the inner condyle of the humerus by the 

 common tendon ; from the ridge above the condyle 

 by fleshy fibres ; from the inner part of the coro- 

 noid process by a second tendinous slip ; and from 

 the fascia, and the septum between it and the next 

 muscle. It is inserted by aflat tendon into an im- 

 pression, an inch in length, on the middle of the 

 outer surface of the radius. 



The muscle is superficial except at the insertion, 

 where it is covered by the radial artery, and some 

 of the outer set of muscles, viz., supinator longus, 

 and radial extensors of the wrist. The pronator 

 forms the inner boundary of the triangular space 

 in front of the elbow ; and its inner border touches 

 the flexor carpi radialis. By gently separating the 

 muscle from the rest, it will be found to lie on the 

 brachialis anticus, the flexor sublimis digitorum, 

 and the ulnar artery and the median nerve : the 

 second small head of origin is directed inwards 

 between that artery and nerve. 



Action. The pronator assists in bringing for- 

 wards the radius over the ulna, so as to pronate 

 the hand. When the radius is fixed the muscle 

 raises that bone towards the humerus, bending the 

 elbow-joint. 



The FLEXOR CARPI RADIALIS (fig. 80, 4 ) takes 

 its origin from the common tendon, from the 

 aponeurosis of the limb, and from the intermuscular 

 septum on each side. The tendon of the muscle, 

 becoming free from fleshy fibres about the middle 

 of the forearm, passes through a groove in the os 

 trapezium, outside the anterior annular ligament, 

 to be inserted mainly into the base of the meta- 

 oarpal bone of the index finger, and by a slip into 

 that of the middle finger. 



The muscle rests chiefly on the flexor sublimis 

 digitorum ; but near the wrist it lies over the flexor 

 longus pollicis a muscle of the deep layer. As low as the, middle of the 

 forearm the muscle corresponds externally with the pronator teres, and 



SUPERFICIAL VIEW OF THE 

 FOREARM (Quain's Arte- 

 ries). 



1. Radial artery with its 



nerve outside. 



2. Uliiar artery and nerve 



where they are super- 

 BeiaL 



3. Pronator teres. 



4. Flexor carpi radialis. 



5. Palmaris longus. 



6. Flexor sublimis. 



7. Flexor carpi ulnaris. 



8. Supinator lougus. 



9. Biceps. 



