SURFACE MARKINGS 217 



of the deltoid 1 inch below the point joining the middle and 

 outer thirds of the clavicle. Internal to the coracoid process is 

 a triangular depression between pectoralis major and deltoid ; in 

 this depression can be felt the axillary artery. 



The rounded contour of the shoulder is formed by the upper 

 end of the humerus covered by the deltoid; both tuberosities can 

 be felt ; the head of the humerus can be felt through the axilla. 



The Axilla. The anterior fold of the axilla is formed by the 

 lower border of pectoralis major and the posterior fold by latis- 

 simus dorsi and teres major ; between the two folds is the prom- 

 inence of coraco-brachialis, behind which can be felt the third 

 part of the axillary artery. High up in the axilla a few 

 lymphatic glands can be felt. 



The Upper Arm. The anterior and posterior borders of the 

 deltoid can be traced in their whole extent; just under the 

 posterior border, about half-way down, the circumflex, artery and 

 nerve and the musculo-spiral nerve enter the arm. The internal 

 supracondyloid triangle, limited by the internal intermuscular 

 septum posteriorly, and whose floor is formed by the inner part 

 of brachialis anticus, contains many important structures ; from 

 without inwards, the brachial artery, the median nerve, the lower 

 part of the basilic vein, the internal cutaneous nerve, and two or 

 three lymphatic glands. 



The external intermuscular septum extends upwards from the 

 external condyle to the insertion of the deltoid, and is pierced a 

 third of the way down by the musculo-spiral nerve. 



The posterior compartment of the upper arm is occupied by 

 the triceps, the tendon of which can be felt at its insertion into 

 the olecranon. 



The brachial artery, overlapped above by coraco-brachialis and 

 below by biceps, can be felt throughout the whole length of the 

 internal bicipital furrow. The course oi. the vessel is mapped 

 out by a line drawn from the inner border of the coraco- 

 brachialis, at the level of the posterior fold of the axilla, to a 

 point (opposite the neck of the radius) J inch below the middle 

 of the bend of the elbow. 



The cephalic vein ascends internal to the outer edge of triceps 

 to the interval between the deltoid and pectoralis major. 



