ABDOMINAL REGION. 201 



the serratus magniis ; posteriorly it furnishes a few fibres, which, 

 detached from the surface of the common abdominal tendon 

 (prepubian), pass between the thighs, and become lost in the 

 muscles of that region. 



Relation. — Externally by cellular tissue to the panniculus and 

 skin. It is continuous with the suspensory ligament of the sheath 

 and dartos in the male, and the elastic envelope of the mamma 

 in the female, in whom it is always thickest. 



Use. — To afford a mechanical support to the abdominal 

 viscera, and conserve muscular action by substituting elasticity 

 for it. On the application of distensile force it yields con- 

 siderably. 



LINEA ALBA. 



The linea alba is a white fibrous cord situated between the 

 inner borders of the two recti-abdominales, to which it gives 

 attachment, as to the other abdominal muscles. Anteriorly it is 

 attached to the inferior surface of the xiphoid cartilage, and 

 posteriorly it becomes confounded with a large tendon, common 

 to the abdominal muscles, the prepubian tendon, which is 

 attached to the anterior border of the pubis, and assists in 

 the formation of the internal commissures of the inguinal canals. 

 Between its posterior and middle third the linea alba is enlarged, 

 and forms a lozenge-shaped space, in the centre of which is the 

 remnant of the umbilicus. The fact of this structure joining the 

 sternum to the pubic symphysis, together with certain co-related 

 features, has induced anatomists to regard the linea alba as 

 representing a rudimentary abdominal sternum. 



OBLIQUUS ABDOMINIS EXTERNUS. 



( Costo-abdominalis. ) 



(Pl. IL 74.) 



The largest and most external muscle of the group, situated on 

 the infero-lateral aspect of the abdomen, and consisting of a fleshy 

 and an aponeurotic portion. It is quadrilateral, its fibres run- 

 ning downwards and backwards. Its aponeurosis commences at 

 a line called the linea semilunaris, and is continued to the linea 

 alba, where it bends with that of the internal oblique. 



Attachments. — By fleshy fibres, anteriorly to the outer surface 

 of the last thirteen or fourteen ribs, just below their middle ; the 



