70 H. D. SENIOR 
as the a. interossea. The intervening part will be called the a. 
poplitea profunda. 
At this stage the a. poplitea profunda has two branches which 
course longitudinally through the posterior crural region. One 
of these arteries resembles, in a general way, the a. tibialis 
posterior of the adult, it may be called the a. tibialis posterior 
superficialis. The other slightly more distal in its place of 
origin is the a. peronaea posterior superficialis (of Hyrtl).7 The 
relations borne by these arteries to the n. tibialis remain constant 
throughout a prolonged period of development. 
The a. tibialis posterior superficialis passes at first backward 
upon the medial side of the n. tibialis to reach its posterior 
aspect. Running upon the posterior aspect of the n. tibialis in 
the leg, it passes into the sole upon the inferior aspect of the n. 
plantaris medialis. The part of the artery which enters the 
sole becomes the a. plantaris medialis of the adult. 
The a. peronaea posterior superficialis passes from the medial 
to the lateral aspect of the n. tibialis by skirting around the 
proximal and lateral sides of a large muscular ramus of the 
nerve.’ It follows the anterior and lateral aspect of the n. 
tibialis as far as the place of origin of the nn. plantares. In this 
situation the artery bifurcates into a lateral and a medial branch. 
The branches are both short and end blindly. 
Two branches now spring from the lateral side of the a. 
femoralis. One of these is situated upon the proximal side of 
the r. saphenus and represents the r. musculo-articularis of the 
adult a. genu suprema. The other is the a. circumflexa femoris 
lateralis of the adult a. profunda femoris. 
The branches arising from the medial side of the a. femoralis 
which will be discussed under stages E and F. 
The a. glutaea superior is present and takes origin from the 
root of the a. ischiadica. 
7 According to the system of nomenclature in use at the present time, the 
adjective ‘posterior’ as used by Hyrtl is redundant. In view of the essentially 
fugitive nature of anatomical terminology it has seemed unnecessary to modify 
Hyrtl’s original term, which adequately meets the requirements of the case. 
8 This is resolved later into the rami musculares for the mm. popliteus, 
tibialis posterior, flexor digitorum longus, and flexor longus hallucis. 
