DISSECTION OF THE BACK. 



dissecting table. The head is to be depressed and fastened with 

 hooks so as to make tense the neck. 



SURFACE ANATOMY. Before commencing the dissection of any 

 part the student should examine the surface of the body so as to 

 define the bony and other landmarks by which the surgeon or 

 physician is guided in his practice. At the upper part of the neck, 

 posteriorly, in the middle line will be felt the external protuberance 

 of the occipital bone, and running outwards from this will be found 

 the superior curved line of the same bone. Passing downwards and 

 outwards from this to the upper part of the shoulder is a ridge 

 produced by the outer border of the trapezius muscle. 



At the lower part of the neck in the middle line the prominent 

 spine of the seventh cervical vertebra is readily found, and the 

 spines of the one or two succeeding dorsal vertebra?. Below this 

 the spines of the vertebrae can be felt as the fingers are passed down 

 the furrow in the middle of the back, but the spines are much 

 obscured by the strong ligaments which pass over and between 

 them. The furrow is produced by the strong erector spince muscles 

 which run longitudinally on either side. At the lower end of the 

 back the series of spines can be traced on to the sacrum, at the 

 lower part of which they disappear, and the coccyx is then felt 

 bending forwards at the bottom of the furrow between the two 

 sides of the buttock. At the side of the back the crest of the ilium 

 runs outwards on either side, its highest part being on the same 

 level as the spine of the fourth lumbar vertebra and its posterior 

 superior spine lying at the bottom of a little depression opposite the 

 second sacral spine. The lower four or five ribs can be felt below 

 the scapula, and it is to be remembered that the twelfth rib is often 

 short, and its tip can, in those cases, only be made out by deep 

 pressure at the outer border of the erector spinse muscle, two inches 

 or so above the iliac crest. The upper angle, the vertebral border, 

 the lower angle, the spine, and acromion process of the scapula, 

 and the outer part of the clavicle should next be made out, 

 and the matter will be made easier if the limb be moved about 

 during the examination. When the limb is placed down beside 

 the body the upper angle of the scapula is opposite the second 

 intercostal space, the root of the spine is on a level with the spine 

 of the third dorsal vertebra, and the lower angle is usually over the 

 seventh intercostal space. Finally, running upwards to the upper limb 

 from the side of the body is the fold produced by the latissimus dor si 

 muscle, which forms the posterior boundary of the armpit, or axilla. 



Dissection, The first step is to raise the skin in two flaps by 

 means of the following incisions : (1) from the spine of the seventh 

 cervical vertebra along the middle line to the lower end of the 

 sacrum (fig. 1, A, B and c) ; (2) transversely outwards from the spine 

 of the seventh cervical vertebra to the outer border of the acromion 

 (fig. 1 , A E) ; (3) upwards and outwards from the last dorsal spine 

 along the posterior fold of the axilla to the upper limb (fig. 1, A F) ; 

 (4) outwards from the lower end of the median incision two-thirds 

 of the way along the iliac crest (fig. 1, A G). The two flaps of 



