2l8 



ABDOMEN 



vertebrae needs further explanation. As it approaches the 

 vertebral column it splits into three layers or lamellae ; the 

 posterior lamella is attached to the tips of the spinous processes, 

 the anterior lamella to the roots of the transverse processes, and 

 the middle lamella to the tips and adjacent sides of the 

 transverse processes. Two compartments are thus formed ; 

 the posterior of the two is occupied by the sacro-spinalis 

 (O.T. erector spinae), whilst the anterior contains the 

 quadratus lumborum. The points referred to cannot be 

 demonstrated at this stage of the dissection, but a reference 

 to Fig. 98 will help the student to understand the arrangement. 



. Fascia 

 transversalis 



M. obliquus 

 externus 



- M. obliquus 

 interims 

 M. transversus 

 abdominis 



M. latissimu* 

 dorsi 



M. serratus 



posterior 

 inferior 



M. sacro- 

 spinalis 



FIG. 98. Lumbo-dorsal fascia and sheath of Rectus abdominis. 

 The dotted line represents the Peritoneum. 



Anteriorly, the fibres of the transversus abdominis muscle 

 end in a strong aponeurosis, which is inserted into the linea 

 alba, the pubic crest, and the ilio-pectineal line. Towards 

 the aponeurosis the fleshy fibres for the most part run in 

 a transverse direction. The lower fibres, however, take a 

 curved course downwards and medially, so that the muscle 

 presents an arched lower margin. 



The dissector has already seen that the lowest portions ot 

 the aponeuroses of the internal oblique and the transverse 

 muscles blend to form the/tf/r inguinalis (O.T. conjoined tendon]. 

 It is through the medium of the falx inguinalis that the 



