tvbdlvivS 



cusfa-itr. mtrr.Z/ I 



Thifffoid 



lint 



FIG. 53. Lower surface of left clavicle. The various areas and ridges can be found at once on the bone 

 Observe that Pectoralis major is in close relation with the rhomboid ligament and costo-coracoid 

 membrane covering Subclavius. The outer part of Subclavius, however is separated from Deltoid 

 by an interval filled with soft tissue, to allow of the play of the latter muscle in movements of the arm. 

 The costo-coracoid membrane reaches the chest-wall and Pectoralis minor by passing down the rhom- 

 boid ligament, while its outer part reaches the muscle by passing down the conoid ligament to the 

 coracoid process. To understand the relation between Supraspinatus and the area behind the trapezoid 

 ridge, see Fig. 51. 



F' G - 53 A - A scheme of a section through the clavicle to show the different planes which come into relation 

 with the bone. The descending cervical nerves cross it deep to the 1'latysma, the suprascapular 

 vessels run behind it in the attachment of the omo-hyoid fascia, and the Sterno-mastoid and Traprzius 

 are in the plane of the vaginal fascia. 



Fir.. 54. Left clavicle seen from the front. A is the blunt edge which lies between the areas for Stc-rno- 

 mastoid and Pectoralis major ; the presence of two large muscular surfaces gives the inner third of 

 the bone a somewhat prismatic shape on section, moulded on the original cylindrical shape of the 

 shaft. I' indicates the interval between Pect. major and Deltoid areas, on which there may be a vi-in 

 joining the cephalic and external jugular ; this is, in the embryo, one of the main venous channels which 

 drain the limb-bud. 



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