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, %) and the intermediate portion (Fig. 80, 7) 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, partly 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. 77, 1), which is attached at its radial and ulnar 
ends to the carpus, and which holds in place the tendons of the 
