THE DISSECTION OF THE BACK 



165 



dissector of the upper limb must finish his share of the dissection of the 

 back, so as to allow the dissector of the head and neck to begin the 

 examination of the deeper structures on the dorsal aspect of the trunk. 



Three days are allowed for this dissection, and these may be disposed 

 of in the following manner : On the first day, all the muscles, fascige, 

 nerves, and blood vessels of the back, with the exception of those in 

 connection with the sub -occipital triangle, should be studied; on the 

 second day, the sub-occipital triangle must be examined ; and on the third 

 day the medulla spinalis (O.T. spinal cord) must be displayed. 



Musculi Serrati Posteriores. These are two thin sheets 

 of fleshy fibres, which are placed upon the posterior aspect 



t Ilio-costalis 



Quadratus 

 "lumborum 



-^--Psoas major 



Serratus 

 post. inf. 



Latissimus 

 dorsi 



Transversus 



abdominis 



Internal 



oblique' 



External 



oblique 



Fascia 

 transversalis' 



FIG. 71. Diagram to show the Connections of the Lumbo-dorsal Fascia. 



of the thoracic wall. The serratus posterior superior is much 

 the smaller of the two ; it arises by a thin aponeurotic tendon 

 from the lower part of the ligamentum nuchae; from the spinous 

 process of the seventh cervical, vertebra ; and from the spinous 

 processes of the upper two or three thoracic vertebrae. It 

 passes obliquely downwards and laterally, and is inserted into 

 the outer surfaces of the second, third, fourth, and fifth ribs, 

 a short distance anterior to their angles. 



The serratus posterior inferior will be brought into view by 

 raising and throwing medially that portion of the latissimus 

 dorsi which the dissector of the upper limb has left attached 

 to the lumbo-dorsal fascia. It takes origin from the spinous 

 processes of the last two thoracic and upper two lumbar 



