course of the vessel may be mapped out upon the surface by drawing a line from 
the inner border of the coraco-brachialis, at the level of the posterior fold of the 
axilla, downwards to a point (opposite the neck of the radius) $ in. below the 
middle of the bend of the elbow. In ligaturing the vessel, the edges of the 
coraco-brachialis and biceps muscles, together with the median nerve, furnish Ha 
able guides to the artery, the mobility of which is often a source of trouble 1 
performing the operation. 
The basilic vein, which is superficial to the deep fascia in the lower third of the 
upper arm, is visible in the internal supracondyloid triangle and the lower part of 
the internal bicipital groove. The cephalic vein ascends a little internal to the 
outer edge of the triceps to reach the interval between the deltoid and pectoralis 
THE ELBOW. 1203 
major. 
The surface guide for the median nerve is the same as that for the brachial 
artery. The ulnar nerve is indicated superficially by a line extending from the 
outer wall of the axilla immediately behind the prominence of the coraco-brachialis, 
to the back of the internal condyle; in the upper half of the arm the nerve lies 
close behind the brachial artery under cover of the basilic vein, while in the lower 
half it lies a little behind the internal intermuscular septum, partially embedded 
in the fibres of the inner head of the triceps. To map out the course of the musculo- 
spiral nerve, first mark the point where it pierces the external intermuscular 
septum, viz. the junction of the upper and middle thirds of a line extending from 
the insertion of the deltoid to the external condyle; from this pot draw a line 
obliquely downwards and forwards to the front of the external condyle, where the 
nerve divides into its radial and posterior interosseous branches. To map out the 
nerve as it lies in the musculo-spiral groove, draw a line from the same point 
obliquely upwards across the prominence formed by the outer head of the triceps to 
the junction of the posterior fold of the axilla with the upper 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 below the 
point where it pierces the external intermuscular septum, and carry it obliquely 
upwards and slightly backwards through the outer head of the triceps. 
The shaft of the humerus, nowhere subcutaneous, is most readily manipulated 
in the region of the insertion of the deltoid, upwards along the outer head of the 
triceps, al downwards behind the eeeual supracondyloid ridge. The surgical 
neck, situated between the tuberosities and the attachments of the muscles inserted 
into the region of the bicipital groove, is related to the outer wall of the axilla, and 
is on a level with the junction of the upper and middle thirds of the deltoid; at 
the same level are the circumflex vessels and nerves. 
| 
| The shaft may be cut down upon with least injury to soft parts: (1) in its upper 
third, anteriorly, by an incision extending downwards through the anterior fibres of the 
deltoid, parallel, and a little external, to the bicipital groove ; the sheath of the biceps 
will eis be avoided, and the small anterior circumflex artery will be the only vessel 
/ divided. (2) In the upper third, posteriorly, by an incision through the posterior fibres 
of the deltoid, the bone being reached just external to the origin of the outer head of the 
triceps, thus avoiding the musculo-spiral nerve ; the circumflex vessels and nerves will be 
exposed at the upper part of the wound. (3) In the lower third, by an incision extending 
upwards from the back of the external condyle a little to the inner side of the external 
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 yreat importance. The 
epicondylar processes of the humerus are both subcutaneous and upon the same 
level, the internal bemg 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 
