THE ELBOW. 1449 



point draw a line obliquely distally and forwards to the front of the lateral epi- 

 condyle, where the nerve, divides into its superficial and deep branches. To map 

 out the nerve as it lies in the radial groove, draw a line from the same point 

 obliquely proximally across the prominence formed by the lateral head of the triceps 

 to the junction of the posterior fold of the axilla with the arm. In fractures of 

 the humerus in the neighbourhood of the insertion of the deltoid, the nerve is not 

 infrequently lacerated, or so involved in the callus as to produce the condition 

 known as " drop-wrist'' the result of paralysis of the extensor muscles of the 

 forearm. To cut down upon the nerve, commence the incision a little distal to the 

 point where it pierces the lateral intermuscular septum, and carry it obliquely 

 proximally and slightly backwards through the lateral head of the triceps. 



The shaft of the humerus, nowhere subcutaneous, is most readily manipulated in 

 the region of the insertion of the deltoid, proximally along the lateral head of the 

 triceps, and distally behind the lateral supracondylar ridge. The surgical neck, 

 situated between the tubercles and the attachments of the muscles inserted into 

 the region of the intertubercular sulcus, is related to the lateral wall of the axilla, and 

 is on a level with the junction of the proximal and middle thirds of the deltoid ; at 

 the same level are the circumflex vessels and the axillary nerve. 



The shaft may be cut down upon with least injury to soft parts : (1) in its proximal 

 third, anteriorly, by an incision extending distally through the anterior fibres of the 

 deltoid, parallel, and a little lateral, to the intertubercular sulcus ; the sheath of the biceps 

 will thus be avoided, and the small, anterior circumflex artery will be the only vessel 

 divided. (2) In the proximal third, posteriorly, by an incision through the posterior fibres 

 of the deltoid, the bone being reached just lateral to the origin of the lateral head of the 

 triceps, thus avoiding the radial nerve ; the circumflex vessels and the axillary nerve will be 

 exposed at the proximal part of the wound. (3) In the distal third, by an incision extending 

 upwards from the back of the lateral epicondyle a little to the medial side of the lateral 

 intermuscular septum. 



THE ELBOW. 



In injuries about the elbow the diagnosis rests mainly upon the relative 

 positions of the bony points, which are, therefore, of great importance. The 

 epicondyles of the humerus are both subcutaneous and upon the same level, the 

 medial being the more prominent. In the extended position of the elbow the 

 tip of the olecranon is on a level with a line joining the epicondyles ; when the 

 forearm is flexed the olecranon descends, and when full flexion is reached it 

 lies 1 in. distal to the epicondyles, and in a plane anterior to the posterior 

 surface of the distal end of the humerus. The head of the radius, which lies nearly 

 1 in. below the lateral epicondyle, is best manipulated from behind by placing 

 the thumb upon it, while the semi-flexed forearm is being alternately pronated 

 and supinated. Upon the lateral part of the posterior aspect of the extended 

 elbow is a distinct dimple, which overlies the radio-humeral articulation; this 

 dimple, along with the hollows on each side of the olecranon, becomes effaced in 

 synovial thickenings and effusions into the joint. The coronoid process is situated 

 too deeply to be distinctly felt. The distal epiphysis of the humerus includes the 

 articular portion of the distal extremity and the lateral epicondyle ; it is, therefore, 

 small and almost entirely intra-articular, so that foci of disease in its neighbour- 

 hood soon invade the cavity of the joint. The medial epicondyle ossifies as a 

 separate epiphysis which unites with the distal end of the diaphysis. In inter- 

 preting skiagrams of the elbow of children about six years of age and upwards, care 

 must be taken not to mistake the centre of ossification in the lateral portion of the 

 distal epiphysis of the humerus for a fracture. In the commonest dislocation of 

 the elbow, viz., with backward displacement of both bones of the forearm, the 

 normal relative position of the bony points is lost, whereas in a transverse supra- 

 condylar fracture the normal relations are maintained. In the child the head 

 of the radius is relatively smaller, and less firmly kept in position by the 

 annular ligament than in the adult, so that it is liable to be "partially dis- 

 located, giving rise to the condition known as "pulled elbow." 



