[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 the podophyllous plexuses, and following the direction of the artery of the same name.  The circumflex vein terminates by forwarding branches to concur in the formation of the superficial coronary plexus.

(b) The Podophyllous or Laminal Plexus.—­The podophyllous veins anastomose below with the circumflex vein of the solar plexus, and above with the veins of the coronary plexus.

(c) The Coronary Plexus.—­This proceeds from the podophyllous, the intra-osseous, and the solar networks, and consists of a central and two lateral parts.