lunar sinus) and anastomoses with
the corresponding artery of the opposite side. The circle of vessels so
formed is called the _Plantar Arch_ or the _Semilunar Anastomosis_.

[Footnote A: The epithet 'ungual' is added by Chauveau to distinguish
these arteries from the properly so-called plantar arteries--the terminal
divisions of the posterior tibial artery.]

From the semilunar anastomosis radiate two main groups of arterial
branches, an ascending group and a descending one. The _ascending_ branches
penetrate the substance of the os pedis, and emerge by the numerous
foraminae on its laminal surface. The _descending_ branches, larger in size,
also penetrate the substance of the pedal bone, and emerge in turn from
the foraminae cribbling its outer surface--in this case the set of larger
foraminae opening on its inferior edge. Having gained exit from the bone,
their frequent anastomosis, right and left, with their fellows forms a
large vessel following the contour of the inferior edge of the os pedis.
This constitutes the _Circumflex Artery of the Toe_.

E. THE VEINS.

These commence at the foot with a series of plexuses, which may be
described as forming (1) AN INTERNAL OR INTRA-OSSEOUS VENOUS SYSTEM, and
(2) AN EXTERNAL OR EXTRA-OSSEOUS VENOUS SYSTEM.

1. THE INTRA-OSSEOUS VENOUS SYSTEM.--This is a venous system within the
structure of, and occupying the semilunar sinus of the os pedis. It follows
in every respect the arrangement of the arteries as before described in the
same region. Efferent vessels emerge from the plantar foraminae, follow the
plantar fissures, and ascend within the basilar processes of the os pedis.
Here they lie under shelter of the lateral cartilages, and assist in the
formation of the deep layer of the coronary plexus of the extra-osseous
system.

2. THE EXTRA-OSSEOUS VENOUS SYSTEM.--This may be regarded as a close-meshed
network enveloping the whole of the foot. Although a continuous system, it
is best described by recognising in it three distinct parts:

_(a) The Solar Plexus_.
_(b) The Podophyllous Plexus_.
_(c) The Coronary Plexus_.

_(a) The Solar Plexus_.--The veins of this plexus discharge themselves in
two directions: (1) _By a central canal_ or canals running along the bottom
of the lateral lacunae of the plantar cushion to gain the deep layer of the
coronary plexus. (2) _By the Circumflex or Peripheral Vein of the Toe_, a
canal formed by ramifications from the solar and