238 ANTERIOR BRACHIAL REGION. 



neath the annular ligament into the palm of the hand, and are 

 inserted into the base of the second phalanges of the fingers, splitting 

 at their terminations to give passage to the tendons of the deep flexors; 

 thence its designation, perforatus. In the thecae of the fingers several 

 small tendinous fasciculi are generally found which pass between the 

 phalanges and the edges of the tendons ; these have been termed the 

 vincula accessorial. 



Relations. In the fore-arm. By its anterior surface with the 

 pronator radii teres, flexor carpi radialis, palmaris longus, flexor carpi 

 ulnaris, and the deep fascia. By its posterior surface with the flexor 

 profundus digitorum, flexor longus pollicis, ulnar artery, veins, and 

 nerve, and median nerve. This muscle frequently sends a fasciculus to 

 the flexor longus pollicis or flexor profundus. In the hand : its ten- 

 dons, after passing beneath the annular ligament, are in relation super- 

 ficially with the superficial palmar arch, and palmar fascia ; and deeply 

 with the tendons of the deep flexor and lumbricales. 



The FLEXOR CARPI ULNARIS arises by two heads, one from the 

 inner condyle, the other from the olecranon and upper two-thirds of 

 the inner border of the ulna. Its tendon is inserted into the pisiform 

 bone, and base of the metacarpal bone of the little finger. 



Relations. By its anterior surface with the fascia of the fore-arm, 

 with which it is closely united superiorly. By its posterior surface 

 with the flexor sublimis digitorum, flexor profundus, pronator quadra- 

 tus, and ulnar artery, veins, and nerve. By its radial border with the 

 palmaris longus, and in the lower third of the fore-arm with the ulnar 

 vessels and nerve. The ulnar nerve, and the posterior ulnar recurrent 

 artery, pass between its two heads of origin. 



Deep layer. 



Flexor profundus digitorum, 

 Flexor longus pollicis, 

 Pronator quadratus. 



Dissection. This group is brought into view by removing the flexor 

 sublimis, and drawing aside the pronator radii teres. 



The FLEXOR PROFUNDUS DIGITORUM (perforans) arises from the 

 upper two-thirds of the ulna and part of the interosseous membrane, 

 and terminates in four tendons, which pass beneath the annular liga- 

 ment, and between the two slips of the tendons of the flexor sublimis 

 (hence its designation, perforans), to be inserted into the base of the 

 last phalanges. The tendon of the index finger is always distinct 

 from the rest, the other three tendons being more or less intimately 

 connected by cellular tissue and tendinous slips. 



Four little muscular fasciculi, called lumbricales, are connected with 

 the tendons of this muscle in the palm. They will be described with 

 the muscles of the hand. 



Relations. In the fore-arm. By its anterior surface with the flexor 



