PECTORAL REGION 7 



Until the dissection of the axilla is completed the dissectors of the arm 

 and of the head and neck will find it advantageous to arrange to work 

 at different hours. The dissector of the head and neck, at this stage, is 

 engaged on the posterior triangle of the neck, and the dissection of the 

 triangle cannot be well done unless the arm is placed close to the side 

 and the shoulder depressed. For the dissection of the axilla the arm should 

 be stretched out at right angles to the thorax. A compromise between 

 these two positions always results in discomfort to both dissectors. 



Five days are allowed for the examination of the axilla 

 and the muscles which pass to the upper extremity from the 

 anterior portion of the thoracic region of the body. The 

 following table will 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 ; (6} 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 ; (/) 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. 



Before commencing the dissection of the axillary region 

 draw your finger along the clavicle from its sternal to its 

 acromial end. Note that in the medial two-thirds of its 

 length the bone curves forwards to give room for the passage 

 of vessels and nerves from the neck to the axilla. The lateral 

 third is curved backwards. Place your finger in the delto- 

 pectoral triangle below the junction of the intermediate and 

 lateral thirds of the clavicle, and note that the great pectoral 

 muscle lies to its medial side and the deltoid muscle to its 

 lateral side; both muscles spring from the anterior aspect 

 of the clavicle (see Fig. 10). Push your finger upwards and 

 backwards in the triangle under the medial border of the 

 deltoid until the coracoid process is distinctly felt. Next 

 examine the articulations of the clavicle. Little or no 

 prominence is formed by the lateral extremity of the bone 

 its superior surface lies in the same plane as the superior 

 i lc 



