258 



THE VASCULAR SYSTEM. 



with the hindmost part of the M. oNiquus aldominis externns, 

 and the hinder portion of the posterior lymph-heart. Anteriorly 

 the floor is depressed between the M. obliqmis aldominis and the 

 M. glutaeus, the depression leading- to a canal, which communicates 

 with the abdominal cavity. 



B. The Lymph-sacs of the Anterior Extremity. 



a. The septa. 



(i) The axillary septum (Septum axillare], (Figs, 1700', a", 

 171) is practically a portion of the ventral septum, which divides 

 at the root of the arm to enclose it. The dorsal and ventral por- 

 tions of this circular septum have received special names. 



a. The dorsal axillary septum 

 (Septum axil/are dorsale} crosses the 

 M. triceps and joins the pectoral 



septum. 

 .' 



ft. The ventral axillary septum 



(Septum axillare dorsale) passes 

 through the axilla and joins the 



Transverse section tlirough the trunk in the pectoral Septum, 

 region of the iliac lymph-sac. 



Fig. 172. 



Urostyle. 



Skin. 



Muscles of abdominal wall. 



Dorsal lymph-sac. 



Lateral lymph-sac. 



Iliac lymph-sac. 



The circular axillary septum has 

 attached to it the following? : 



(2) The posterior brachial sep- 

 tum (Sept inn Iraclnale po-sticum (Fig\ 

 169 s); it is attached along the 



middle line of the extensor surface of the arm (long head of the 

 M. triceps] to the elbow and to the forearm (MM. anconaei], then passes 

 obliquely over the volar surface of the hand to the fourth finger. 



(3) The anterior brachio-ulnar septum (Septum Ijrachiale anticuw 

 iilnare), (Fig. 1 70 *") commences at the same point as the foregoing, 

 passes obliquely over the outer head of the M. triceps, and is con- 

 tinued over the M, flexor antibrackii lateralis, M. supinator longus, and 

 M. extensor digUornm commimis, to the dorsal surface of the fourth 

 finger. 



(4) The anterior brachio-radial septum (Septum Lmchia/e an- 

 ticum radiale), (Fig. 170 s'"} passes from the outer angle of the wall 

 of the pectoral lymph-sac, over the inner head of the M. triceps and 

 M. flexor carpi radialis to the thumb. 



b. The lymph-sacs are enclosed by these three septa ; they are 

 four in number : 



