2 THE UPPER EXTREMITY 



by the dissector of the upper extremity, and five days are 

 allowed for the examination of the axilla and the muscles 

 which pass to it from the anterior portion of the thoracic 

 region of the body. The following table may be found useful 

 in regulating the amount of work which should be carried out 

 on each day : 



First Day. -(a) Surface anatomy ; (b} reflection of the skin ; (c) cutane- 

 ous vessels and nerves of the anterior and lateral aspects of the thorax ; 



(d) examination of the fascia of the pectoralis major and the axillary fascia ; 



(e) the cleaning of the pectoralis major ; (/) the reflection of the pectoralis 

 major. 



Second Day. (a) The examination of the costo-coracoid membrane and 

 the structures piercing it ; (b} the removal of the costo-coracoid membrane 

 and the examination of the structures posterior to it. 



Third Day. (a) The cleaning of the pectoralis minor ; (b) the cleaning 

 of the contents of the axilla below the pectoralis minor. 



Fourth Day. (a) The reflection of the pectoralis minor ; (b} the com- 

 pletion of the cleaning of the contents of the axilla ; (c) the cleaning of the 

 serratus anterior ; (d) the cleaning of the posterior wall of the axilla ; (e) 

 the reflection of the subclavius ; (f) the examination of the sterno- 

 clavicular articulation and the disarticulation of the clavicle at the sterno- 

 clavicular joint. 



Fifth Day. (a) The brachial plexus and a general review of the axilla 

 and its contents. 



Surface Anatomy. Before proceeding to the actual dis- 

 section of any region, the student should make it an invariable 

 practice to familiarise himself with the bony prominences 

 within its area. It is by using these as landmarks that the 

 surgeon is enabled to establish the positions of the component 

 parts of the body in the living subject. 



At the lower part of the neck the entire length of the 

 clavicle can be felt under the skin (Fig. i), and as the student 

 follows its curves, with his finger, he can recognise the positions 

 of the origins of the pectoralis major and deltoid muscles from 

 its anterior border (Fig. 5). In a few instances these muscles 

 may present an unbroken line of origin from the sternal to the 

 acromial ends of the bone, but in the vast majority of cases 

 a triangular interval is left between them. This is marked 

 on the surface by a shallow depression, termed the delto- 

 pectoral triangle (infraclavicular fossa), and it is rendered 

 all the more apparent by the prominence of the shoulder 

 on its lateral side, and the sharp backward curvature of the 

 clavicle immediately above it. If the finger be placed in 

 this triangle, and pressed backwards and laterally, it will rest 

 upon the medial side of the coracoid process of the scapula. 



