The Arm. 57 



inner side. The collateral circulation, after ligature of the 

 brachial at this point, is carried on (i) by the termina- 

 tion of the superior profunda anastomosing with the 

 radial recurrent artery in front of the external condyle, 

 (2) by the communication of the inferior profunda and the 

 anastomotica magna with the anterior ulnar recurrent in 

 front of the internal condyle, (3) by these same vessels 

 anastomosing with the posterior ulnar recurrent, behind 

 this condyle, and (4) by the anastomoses of the posterior 

 articular, the interosseous recurrent and the anastomotica 

 magna, behind the external condyle. 



Fracture of the Humerus. The anatomical neck 

 is the narrow groove, separating the rounded head of the 

 humerus from the tuberosities, externally, and from the 

 shaft, internally. The epiphysis is the cap-shaped upper 

 end of the humerus resting upon the dome-like extremity 

 of the shaft, while the epiphyseal line, slightly convex at its 

 centre, runs from the anatomical neck, on the inner side 

 of the bone, to a point immediately below the tuberosities 

 on the outer side. The suigical neck is the triangular shap- 

 ed portion of bone lying between the epiphyseal line, 

 above, and the insertion of the pectoral muscles, below. 

 Fracture of the anatomical neck is rare, and when it does 

 occur, the fragments may be impacted, or non-impacted. 

 Should the fracture be impacted, the fragments will be 

 united by bony tissue, whereas if it be non-impacted, then 

 union, if it occur, will be fibrous in character. In the latter 

 variety of fracture the non-impactedone would be led 

 to think that union would not result, since, there is 

 no bloodvessel bringing blood to the fractured head, as 

 there is, in the case of the hip joint, but, notwithstanding 

 this absence of adequate blood supply, non-union, in this 

 fracture, is very uncommon. Fracture or rather separation 

 of the epiphysis should always be kept in mind when in- 



