48 THE UPPER EXTREMITY 



from the anterior wall of the thorax and take the extremity 

 to a separate table for further dissection. 



SHOULDER SCAPULAR REGION. 



In the dissection of this region the following parts must be 

 studied : 



1. Cutaneous nerves of the shoulder. 



2. Deep fascia. 



3. Deltoid muscle. 



4. Sub-acromial bursa. 



5. Anterior and posterior circumflex vessels of the humerus. 



6. Axillary (circumflex) nerve. 



7. Circumflex scapular artery. 



8. Subscapularis muscle. 



9. Supraspinatus, infraspinatus, teres minor, and teres major muscles. 



10. Bursse in connection with the shoulder -joint. 



11. Suprascapular nerve and transversa colli artery. 



12. Acromio-clavicular joint, and the coraco-acromial arch. 



Muscles inserted into the Clavicle and Scapula. The insertions of 

 the muscles which have already been divided should first engage the 

 attention of the student. They should be carefully defined and the 

 precise extent of each studied. Begin with the orno - hyoid, which 

 springs from the superior border of the scapula ; then deal in the same 

 way with the levator scapula, rhomboideus minor and major, which 

 are attached to the vertebral border of the bone, and the serratus anterior, 

 which is inserted into the costal aspect of the medial and inferior angles, 

 and the intervening portion of the vertebral border of the scapula. The 

 insertion of the pectoralis minor into the coracoid process, and of the 

 trapeziits into both clavicle and scapula, should also be thoroughly ex- 

 amined. When this has been done these divided muscles may be removed, 

 with the exception of about half an inch of each, which it is advisable to 

 leave attached to the bones for future reference. 



Dissection. A block should now be placed in the axilla, and the skin 

 removed from the upper and lateral aspects of the shoulder as low down as 

 the insertion of the deltoid. Commence in front and proceed from before 

 backwards, taking care to leave the fatty superficial fascia in its place. 



Nervi Cutanei (Cutaneous Nerves). In the superficial 

 fascia, which is thus laid bare, cutaneous nerves from two 

 different sources must be secured and traced, in order that the 

 area of skin supplied by each may be recognised. They are : 



1. Posterior supraclavicular nerves from the third and fourth cervical 



nerves. 



2. Cutaneous branches from the axillary nerve (circumflex). 



The posterior supraclavicular nerves have already been 

 observed crossing the lateral third of the clavicle and the 

 insertion of the trapezius under cover of the platysma. 

 They have been divided in removing the limb. If the cut 



