FOREARM AND HAND 101 



are the pronator teres, the flexor carpi radialis, the palmaris 

 longus, the flexor digitorum sublimis, and the flexor carpi 

 ulnaris, in that order from the lateral to the medial side. 

 The fleshy belly of the flexor sublimis only partially comes to 

 the surface ; the chief bulk of it is placed upon a deeper plane 

 than the others. The deep group is composed of three 

 muscles, placed in contact with the bones and interosseous 

 membrane of the forearm, viz. the flexor digitorum profundus 

 in relation to the ulna, the flexor pollicis longus in relation 

 to the radius, and the pronator quadratus closely applied to 

 the lower ends of both bones. 



Dissection. The superficial group of muscles should now be dissected. 

 The brachioradialis, which lies along the lateral side of the forearm, may 

 be cleaned at the same time. In the lower part of the forearm the dis- 

 sector will observe that the flexor tendons are enveloped by a loose bursa 

 mucosa as they pass into the palm, under cover of the transverse carpal 

 ligament. A good view of this may be obtained by pulling the tendons 

 upwards. If possible, the sac should be retained uninjured, in order that 

 its full extent may be studied when the palm of the hand is opened up. 

 At this stage it is also well to define the transverse carpal ligament which 

 bridges across the front of the carpus. The tendon of the palmaris longus 

 passes in front of it, whilst close to the pisiform bone the ulnar artery and 

 nerve are placed upon its volar surface, and give the dissector the key 

 to its depth. This vessel, with its accompanying nerve, are bound down 

 to the ligament by a more superficial band of fascia, the ligamentum 

 carpi volare, which passes over them, and which the student is very apt 

 to mistake for the transverse ligament itself. This band of fascia should 

 not be disturbed in the meantime. 



Common Origin of the Superficial Muscles. The five 

 muscles which constitute the superficial group are very closely 

 associated with each other at the elbow indeed, they may 

 be said to arise by a common origin from the front of the 

 medial epicondyle of the humerus. In addition to this they 

 all derive fibres from the investing deep fascia of the limb, 

 near the elbow, and from the strong fibrous septa which pass 

 between the muscles from the deep surface of investing 

 fascia. The pronator teres, the flexor sublimis, and the 

 flexor carpi ulnaris, have likewise additional heads of origin. 



M. Pronator Teres (Pronator Radii Teres). This muscle 

 crosses the proximal half of the front of the forearm obliquely. 

 It arises by two heads, viz. a humeral and an ulnar. The 

 humeral head constitutes the chief bulk of the muscle. It 

 springs from the proximal part of the medial epicondyle of 

 the humerus, and also slightly by fleshy fibres from the distal 

 part of the medial epicondylar ridge. The fascia covering it 



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