200 MYOLOGY. 



Relation. — Externally with the longissimus dorsi ; internally 

 with the vertebrae. 



Action. — To assist in extending the spine. 



INTERTRANSVERSALES LUMBORUM. 



These are small muscular slips, invested by strong tendinous 

 fasciae, running from the transverse process of one lumbar vertebra 

 to the one adjacent. 



Relation. — "With the longissimus dorsi and intertransverse 

 ligaments. 



Action. — To assist in flexing the spine laterally, by bringing 

 these processes nearer to each other. 



Abdominal Region. 



The infero-lateral walls of the abdomen are formed by a large 

 musculo-aponeurotic envelope, consisting of four pairs of muscles, 

 covered externally by the abdominal tunic, the muscles on the 

 right being separated from those on the left by the linea alba, a 

 white fibrous cord extending from the sternum to the pubis. These 

 muscles, the rectus excepted, consist each of a fleshy and an 

 aponeurotic portion, and the general line of demarcation between 

 the aponeurotic and the fleshy region is known as the linea 

 semilvmaris. We have to describe the following structures : — 



Tunica abdominalis. 



Linea alba. 



Muscles. 

 Obliquus abdominis externus. I Rectus abdominis, 

 Obliquus abdominis internus, | Transversalis abdominis. 



TUNICA ABDOMINALIS. 



(Tunica Elasiica). 



The abdominal tunic is an immense expansion, composed of 

 yellow elastic tissue, which covers the external oblique muscles. 

 It is thickest at the pubis, and on each side of the linea alba, 

 thinning as it approaches the sternum, and disappearing at the 

 posterior attachment of the pectoralis magnus muscle. It blends 

 with the external oblique, anteriorly reaching the digitations of 



