9 6 



Anatomy of Skeleton 



The remaining relations of the bone are shown in the figures, and a few short 

 remarks may be made on these (Figs. 76, 77, and 79). 



F. Profundus Dig. Arises by muscle fibre, therefore a smooth area on bone; 

 arises higher on inner side, extending as far as the hollow smooth surface goes, up to 

 side of olecranon bordering on intent 1 lateral ligament : thus the ulnar nerve can 

 pass directly from the ligament on to the muscle. A part of the inner surface of the 

 shaft is free from muscular origin, between the attachments of the little finger and ring 

 finger portions. 



Pronator ridge is made partly by fibres of the interosseous membrane extending 



Cot moid 

 process 



FIG. 75. i, Upper aspect of olecranon : a, surface covered by synovial reflec- 

 tion ; b, area for bursa deep to Triceps : the dotted line in front of b marks 

 the capsular attachment. The bursal area is frequently much smaller or 

 absent, with consequent approximation of Triceps and capsular markings. 

 2, Front surface of coronoid, showing the positions of attachments on its 

 margins and surface. Internal lateral lig. is attached to the tubercle c, and 

 F. sublimis reaches the bone along this band (see Fig. 77). Synovial mem- 

 brane covers the surface a. 3, Inner side of upper end of ulna. The origin 

 of F. profundus reaches the base of olecranon. c, tubercle on coronoid for 

 ligament and F. sublimis ; d, posterior fibres of int. lat. lig. ; e, F. carpi 

 ulnaris (see Fig. 76). 



on to the front of the bone, and partly by aponeurotic fibres on the surface of the 

 muscle. 



Pronator Quadratus. Observe the limited area of origin, and that the inner hall of 

 the muscle is covered by the broad tendon of Flexor profundus, while the outer portion 

 is exposed in part by the narrower tendon of Flexor longus pollicis : this explains 

 why the radial artery lies in one part of its course on the muscle, whereas the ulnar 

 artery does not do so. 



The extensor surface is subdivided by a " vertical ridge " into an area between the 

 ridge and the interosseous border for deep muscles and a smooth strip between the 

 ridge and the subcutaneous border which is for the play of Extensor carpi ulnaris, 

 not affording origin to it. The vertical ridge, traced up, leads to the back of the 

 Supinator brevis origin and outer border of olecranon. 



