2 8o APPLIED ANATOMY. 



A line drawn on the posterior surface of the arm from behind and above the insertion 

 of the deltoid to the groove on the anterior surface between the brachialis anticus and 

 brachioradialis (supinator longus) just above and to the inner side of the external 

 condyle will indicate its course. If exposed during an operation bleeding from the 

 accompanying (superior) profunda artery may be expected. The median and ulnar 

 nerves give off no branches in the upper arm. The median can be readily located 

 by its relation to the artery. It lies to the outer and anterior side of the brachial 

 artery above, then in front, and then to its inner side below. The ulnar nerve lies 

 to the inner side of the artery and between it and the vein posteriorly. In the middle 

 of the arm, it leaves it to pierce and pass beneath the internal intermuscular septum 

 and thence behind the medial (internal) condyle-. Operations involving it would 

 be accompanied by bleeding from its companion the superior ulnar collateral artery 

 (inferior profunda). 



In operations on the lower portion of the bone the position of the inferior ulnar 

 collateral (anastomotica magna), 5 cm. (2 in.) above the elbow, should be borne in 

 mind. It runs on the brachialis anticus muscle and towards the inner and not the 

 outer side. Incisions on the outer side will encounter the cephalic vein in the external 

 bicipital furrow. Incisions on the inner side will encounter the basilic vein ; at the 

 junction of the lower and middle thirds of the arm it pierces the deep fascia. 



REGION OF THE ELBOW. 



The elbow is so named because at this point the arm is usually bent. A joint is 

 here inserted which permits of flexion and extension ; when the arm is fully extended 

 the ' ' elbow ' ' might be said to have disappeared. The lower end of the humerus 

 forms the proximal portion of the joint and the upper ends of the ulna and radius form 

 its distal portion. Ligaments join these bones together to form the joint, and the 

 blood-vessels and nerves change in character in this region as they pass from the arm 

 to the forearm. 



The bones are frequently subject to fractures which are of an exceedingly puz- 

 zling and disabling character. The joint becomes luxated and the vessels and nerves 

 are not infrequently injured. A thorough knowledge of the anatomy of the region 

 is absolutely essential to the proper treatment of these affections. 



BONES OF THE ELBOW. 



Humerus. The lower end of the humerus broadens laterally and is slightly 

 concave on its anterior surface ; this causes the articular surfaces to look downward 

 and forward and not backward. It carries two articular surfaces: one, the trochlea, for 

 the ulna, and the other, the capitellum, for the radius. The trochlea, descending 

 lower than the capitellum, causes the line of the joint to incline downward and inward 

 instead of being directly transverse, thus producing the ' ' carrying angle " (Fig. 294). 

 Extending from the edges of the articular surfaces outward, one on each side, are the 

 condyles, medial (internal} and lateral {external). 



Chaussier gave the name epicondyle to the condyles. He called the medial 

 condyle the epitrochlea and the lateral (external) condyle the epicondyle. Henle 

 called the internal condyle the epicondyhis medialis and the external condyle the 

 epicondylus lateralis. The name epicondyle is now quite generally employed by both 

 surgical and anatomical writers to designate the projecting extra-articular portion of 

 the condyles, so that the terms are practically synonymous (Fig. 293). 



From the condyles two ridges run upward. The lateral (^external) supracon- 

 dylar ridge is the more marked of the two and gives origin to the brachioradialis 

 (supinator longus) and the extensor carpi radialis longior muscles, and passes 

 posterior to the deltoid eminence to be continuous with the posterior lip of the 

 radial (musculospiral) groove. The medial (internal} supracondylar ridge is much 

 less prominent than the lateral and soon blends with the shaft of the bone. Above 

 the trochlea and capitellum anteriorly are two fossae, the coronoid and the radial, 

 to receive the -onoid process and head of the radius when the arm is in complete 



