118 



THE OSTEOLOGY AND MYOLOGY 



latter, along a groove over the head of the radius, and is inserted into the base of the index 

 metacarpal. 



Extensor carpi radialis hrevior. — (Fig. 29, i, and fig. 30, c.) As long as the preceding 

 and rather larger, with a stouter, flatter tendon. It arises lower down on the condylar 



ridge, and from the condyle itself; it lies alongside the 

 preceding ; its tendon occupies the same groove in the ra- 

 dius ; it is inserted into the base of the middle metacarpal. 

 Pronator radii teres. — (Fig. 29, a.) A large, flat- 

 tened muscle arising fleshy from the internal condylar 

 ridge as high up as the foramen ; with no ulnar origin ; 

 crossing obliquely past the brachial flexors to gain the 

 radial side, to be inserted by a broad aponeurosis into 

 the middle third of the radius. The usual action. 



Pronator quadratus. — (Fig. 29, c.) Well developed, 

 with the usual shape, situation and action. It is re- 

 stricted to the lower part of the arm, instead of extend- 

 ing it to the elbow, as in some marsupials. 



Flexor carpi radicdis. — (Fig. 29, h.) A somewhat 

 flattened sj^indle, arising from the inner condyle next 

 below the round pronator, which it separates from the 

 digital flexors ; its origin is blended with that of the 

 latter. Its slender, round tendon, nearly or quite as long 

 as the fleshy part, runs over the head of the radius, to 

 be inserted into the base of the index metacarpal. 



Flexor carjn idnaris. — (Fig. 29, d.) A bi-pinnatifid 

 muscle, larger than either of the foregoing, and, like the 

 long supinator, mainly determining the contour of the 

 part. The posterior vane is larger than the other, and 

 continues fleshy almost or quite to the insertion ; the 

 anterior one is only two-thirds as long, so that the stout 

 tendon occupies part of the anterior border of the muscle. 

 The muscle arises from the internal condyle, the corres- 

 ponding face of the olecranon, the vipper half or two- 

 thirds of the edge of the ulna, and the intermuscular septum between itself and the digital 

 flexors. Its tendon passes over the head of the ulna to be inserted into the most promi- 

 nent bone of the carpus on the ulnar side (pisiform), besides giving off fibres that are 

 continuous with the annular ligament and the general fascia of the parts. The ulnar 

 nerve runs along the inner surface of the muscle. 



Palmaris longus. — (Fig. 29, e.) This is a slender fusiform muscle lying between the 

 last described and the digital flexors, with both of which it appears intimately blended, but 

 may be traced as a distinct fasciculus to the condyle. Its long, slender, round tendon 

 passes a little obliquely outward over the digital flexors, gains the middle of the front of 

 the wrist and there spreads out into the palmar fascia, being specially attached, on the 

 radial side, to the cartilaginous spur that lies appressed upon the ball of the thumb, and 

 correspondingly on the ulnar side, to the pisiform bone. This attachment on the ulnar 



Fig. 30. — Muscles of the right forearm, 

 posterior aspect; natural size. 



