90 H. D. SENIOR 
The branches which arise from this portion of the a. interossea 
are transferred to the a. peronaea. They are the r. coronarius 
malleolaris, part of which becomes the adult r. communicans, 
and the r. perforans. The remainder of the a. interossea has. 
lost its identity at the stage of 22 mm. The r. perforans tarsi 
disappears at about the same period. 
A. ischiadica. The course taken by this part of the axial 
artery is described on page 73. 
The continuity of the a. ischiadica has been broken in the 
region of the glutaeal fold, at the stage of 22 mm. The proximal 
part of the vessel, which has now become the a. glutaea inferior, 
follows the v. ischiadica and the n. cutaneus femoris to the 
surface of the limb where it ends by dividing into cutaneous 
branches. The more distal portion of the artery is involyed, 
with the single perforating artery present at the stage of 22 
mm., in the formation of an extensive plexus upon the posterior 
surface of the m. adductor magnus. _ 
A. peronaea. This artery is clearly recognizable at the stage 
of 22 mm. (p. 79). It may be divided into four parts: 
The first part of the a. peronaea, which extends from the 
origin of the artery to the proximal margin of the m. flexor 
hallucis longus, is a persisting portion of the a. peronaea posterior 
superficialis (p. 74). 
The second part, which lies between the m. tibialis posterior 
and the m. flexor hallucis longus, represents the entire embryonic 
r. communicans inferius (p. 76). 
The third part, which is short and rests upon the interosseus 
membrane near the distal border of the m. tibialis posterior, is 
a persisting portion of the a. interossea (p. 73). 
The fourth part, which ramifies upon the fibula and caleaneum 
in the neighborhood of the lateral malleolus, represents a sur- 
vival of the short portion of the a. peronaea posterior super- 
ficialis and of the entire r. calcaneus lateralis of that vessel 
(p. 74). 
Branches. The r. perforans and r. communicans, belong 
orig nally to the a. interossea. The rr. calcanei laterales are. 
branches of the r. calcaneus lateralis of the a. peronaea posterior 
superficialis. 
