250 



ABDOMEN 



attached to the last rib. Medially, it is attached to the tips 

 of the spines and transverse processes, and to the fronts of the 

 transverse processes of the lumbar vertebrae ; laterally, it is 

 connected with the transversus abdominis and the internal 

 oblique, and, below, it is closely attached to the posterior 

 part of the external lip of the iliac crest. In the pelvic 

 region it is attached to the spines of the sacrum, and to the 

 back of the lower part of the sacrum and to the back of the 

 coccyx. In the lumbar region its posterior lamella covers 

 the rounded column of the sacro-spinalis muscle, and to this 



M. serratus 

 post. inf. 



M. quadratus 

 lumborum 



M. transversus 

 abdominis 



M. obliquus 

 internus 



M. obliquus 

 externus 



Fascia 

 transversalis 



FIG. 114. Lumbar fascia and sheath of Rectus abdominis. 

 The dotted line represents the Peritoneum. 



part the remains of the origin of the latissimus dorsi and 

 the serratus posterior inferior will be found attached. 



Dissection. Clear away the remains of the latissimus dorsi 

 and clean the serratus posterior inferior, which extends upwards 

 and laterally to its attachment to the lower four ribs. It must 

 be cut through at right angles to its fibres and turned aside, its 

 nerves of^supply, from the anterior branches of the lower thoracic 

 nerves, being sought for on its deep surface. The remains of its 

 origin from the lumbar fascia must be cleared away and then 

 a vertical incision must be made through the fascia, midway 

 between the medial and lateral borders of the rounded mass of 

 the sacro-spinalis muscle ; at each end of the longitudinal incision 

 a transverse incision must be made, one just below the last rib 



