THE FOREARM. 



391 



Surgical Anatomy. This muscle, when suddenly brought into very active use, as in the 

 game of lawn tennis, is apt to be strained, producing slight swelling, tenderness, and pain on 

 putting the muscle into action. This is known as "lawn-tennis arm." 



The Flexor carpi radialis lies on the inner side of the preceding muscle. It 

 arises from the internal condyle by the common tendon, from the fascia of the fore- 

 arm, and from the intermuscular septa between it and the Pronator radii teres, on 

 the outside, the Palmaris longus internally, and the Flexor sublimis digitorum 

 beneath. Slender and aponeurotic in structure at its commencement, it increases 

 in size, and terminates in a tendon which forms 

 rather more than the lower half of its length. 

 This tendon passes through a canal on the outer 

 side of the annular ligament, runs through a 

 groove in the os trapezium (which is converted 

 into a canal by a fibrous sheath, and lined by a 

 synovial membrane), and is inserted into the base 

 of the metacarpal bone of the index finger, and 

 by a slip into the base of the metacarpal bone of 

 the middle finger. The radial artery lies between 

 the tendon of this muscle and the Supinator 

 longus, and may easily be tied in this situation. 



Relations. By its superficial surface, with 

 the deep fascia and the integument ; by its deep 

 surface, with the Flexor sublimis digitorum, 

 Flexor longus pollicis, and wrist-joint; by its 

 outer border, with the Pronator radii teres and 

 the radial vessels ; by its inner border, with the 

 palmaris longus above and the median nerve below. 



The Palmaris longus is a slender, fusiform 

 muscle lying on the inner side of the pre- 

 ceding. It arises from the inner condyle of the 

 humerus by the common tendon, from the deep 

 fascia, and the rntermuscular septa between it and 

 the adjacent muscles. It terminates in a slender 

 flattened tendon, which passes over the upper part 

 of the annular ligament, to end in the central part 

 of the palmar fascia and lower part of the annu- 

 lar ligament, frequently sending a tendinous slip 

 to the short muscles of the thumb. This muscle 

 is often absent, and is subject to very considerable 

 variations : it may be tendinous above and muscu- 

 lar below ; or it may be muscular in the centre, with 

 a tendon above and below ; or it may present two 

 muscular bundles Avith a central tendon ; or finally 

 it may consist simply of a mere tendinous band. 



Relations. By its superficial surface, with the 

 deep fascia. By its deep surface, with the Flexor 

 sublimis digitorum. Internally, with the Flexor 

 carpi ulnaris. Externally, with the Flexor carpi 

 radialis. The median nerve lies close to the tendon, 

 just above the wrist, on its inner and posterior side. 



The Flexor carpi ulnaris lies along the ulnar 

 side of the forearm. It arises by two heads, con- 

 nected by a tendinous arch, beneath which pass 

 the ulnar nerve and posterior ulnar recurrent 

 artery. One head arises from the inner condyle of the humerus by the com- 

 mon tendon ; the other from the inner margin of the olecranon and from the 

 upper two-thirds of the posterior border of the ulna by an aponeurosis, common 



FIG. 233. Front of the left forearm. 

 Superficial muscles. 



