212 



MUSCLES OF THE UPPER LIMB. 



the fingers, are formed opposite the first and second phalanges by strong 

 tendinous bands of transverse fibres (ligamenta vaginalia) attached to 

 the rough margins of the pahuar surfaces of the phalanges. Opposite 

 the joints, flexion is secured by the substitution for those bauds of a 

 thin membrane, strengthened by oblique decussating fibres. The teudi 

 nous sheath has a synovial lining, which is simple in front, but poste- 



Fig. 174. 



Fig. 174. — Bones op Two Fixgers, with the insertions of the Tendons. 4 



In A, the tendons of the flexoi- muscles are bound to the finger by the fibrous sheaths. 

 In B, the bands have been removed, as well as the synovial capsules and vincula acces- 

 soria ; 1, metacarpal bone ; 2, tendon of the flexor sublimis ; 3, tendon of the flexor 

 jirofundus ; *, perforation of the sublimis by the profundus tendon ; 4, tendon of the 

 extensor digitorum communis ; 5, one of the lumbricales muscles ; 6, one of the inter- 

 osseous muscles. 



riorly dips between the tendons. A few slender and loose bands 

 (vincula accessoria tendinum) extend from the floor of the sheath to 

 the deep surface of both tendons. Behind each tendon, near its inser- 

 tion, is a short membranous structure (ligamentum breve) which fixes 

 the tendon to the front of the phalanx situated above that into which 

 it is inserted. 



Iti'lathms. — Superiorly, the flexor sublimis is concealed by the other muscles 

 of the superficial set, and is crossed near its radial origin by the radial artery ; 

 it rests on the flexor poUicis longus and flexor profundus, separated from tlie 

 latter hj the median nerve and the ulnar artery. In the palm of the hand, its 

 tendons are covered by the palmar fascia, the superficial palmar arterial arch, and 

 the branches of the median nerve ; and they lie in front of the accompanying- 

 tendons of the flexor profundus. 



Varirfits. — The radial origin of the flexor sulilimis is sometimes wanting. 

 The body of the muscle is occasionally subdivided, so that each of the four 

 tendons has a distinct muscular belly : this happens most frequently with the 

 radial and the little finger part. The tendon to the little finger has been observed 

 to be absent. 



In connection with this muscle may be mentioned an additional small muscle, 

 the radio-ca7'j>(ilix. which has been seen by many anatomists, rising from the outer 

 border of the radius usually aliove the pronator quadratus, and very variably 

 inserted below, into the trapezium magnum, or some other part of the caipus ; 

 and in other cases into one or other of the metacarpal bones. 



A muscular slip is frefiuently given from this muscle to the flexor profundus, 

 or to the flexor longus pollicis. 



The DEEP-SEATED MUSCLES, on the anterior surface of the forearm, 

 are the flexor profundus, flexor pollicis longus, and pronator quadi-atus. 



