172 THE MUSCLES. 



of the olecranon. The muscle covers the capsule of the joint 

 and is closely adherent to it. 



Relations. — Outer (dorsal) surface with the caput laterale 

 (Fig. 75, h) and the intermediate portion (Fig. So,/) of the 

 caput mediale. Inner surface with the bones and the capsule 

 of the joint. 



Action. — Keeps the capsule tense and probably rotates the 

 ulna slightly so as to pronate the hand. 



3. Muscles of the Antibrachium or Forearm. 



Fascia of the Forearm. — The muscles of the forearm are 

 not in contact with the skin, but are covered by the strong 

 antibrachial fascia. This consists of two layers. The super- 

 ficial one is a continuation of the general subcutaneous fascia 

 of the arm ; it covers the forearm as a continuous sheet which 

 becomes thinner distad, and is finally lost near the wrist. The 

 deep layer forms a dense, tendinous sheet which is closely 

 applied to the muscles. It begins partly as a continuation of 

 the general fascia of the arm, joartly from the tendons of the 

 triceps and epitrochlearis muscles. The sheet is attached to 

 the dorsal surface of the ulna, between the extensor carpi 

 ulnaris and the first head of the flexor profundus digitorum. 

 It surrounds the forearm as a continuous sheath. On the lateral 

 surface it dips between the extensor muscles, becoming closely 

 attached to them and forming a partial sheath for each ; it is 

 attached with special firmness to their tendons. On the medial 

 side of the arm the fascia passes smoothly over the flexors 

 without dipping between them ; it is continuous, however, with 

 the border of the pronator teres, and distad of this muscle it is 

 firmly attached to the radius. 



At the wrist the fascia becomes attached to the longitudinal 

 ridges on the dorsal surface of the head of the radius, bridging 

 thus the intervening grooves and holding the tendons in 

 place between the ridges. The fascia then continues to form 

 the dorsal fascia of the hand. On the ventral side of the wrist 

 the fascia becomes thickened to form a strong transverse 

 ligament (Fig. 'jj , 1), which is attached at its radial and ulnar 

 ends to the carpus, and which holds in place the tendons of the 



