54 THE SUPERIOR EXTREMITY 



fascia from the seventh cervical spine to the acromion ; the 

 incision will correspond with the direction of the fibres of the 

 muscle at the level selected. Work gradually downwards, raising 

 the fascia in a continuous layer from the surface of the muscle. 

 Always carry the scalpel in the direction of the muscle fibres, 

 and take care to leave none of the fascia on the surface of the 

 muscle. As the direction of the muscle fibres changes, alter the 

 position of the arm to keep the fibres which are being cleaned on 

 the stretch. In the case of the left trapezius, the preliminary 

 incision through the fascia must be made along the lower margin 

 of the muscle, and the surface of the muscle must be cleaned, 

 from below upwards, to the level of the seventh cervical vertebra. 

 As the deep fascia is removed from the trapezius, and indeed 

 throughout the whole dissection of the back, the cutaneous 

 nerves must be carefully preserved, in order that the dissector 

 of the head and neck may have an opportunity of establishing 

 their continuity with the trunks from which they arise. 



M. Trapezius. The trapezius is a flat, triangular muscle, 

 which lies, in its entire extent, immediately subjacent to the 



FIG. 28. Upper Surface of the Right Clavicle. 



deep fascia. It has a very long origin, which extends along 

 the median plane, from the occiput above to the level of the 

 last thoracic vertebra below. It arises from (i) the medial 

 third or less of the superior nuchal line of the occipital bone 

 and the external occipital protuberance ; (2) the ligamentum 

 nuchae and the spine of the seventh cervical vertebra ; (3) the 

 tips of the spines of all the thoracic vertebrae, as well as the 

 supraspinous ligaments which bridge across the intervals 

 between them (Figs. 26, 27). 



In the lower cervical and upper thoracic regions the tendinous fibres by 

 which the muscle arises lengthen out so as to form a flat tendon, which, 

 taken in conjunction with the corresponding aponeurosis of the opposite 

 side, exhibits an oval outline. 



As the fibres of the trapezius pass laterally they converge 

 to their insertions into the two bones of the shoulder-girdle. 

 The occipital and upper cervical fibres incline downwards, and, 



