The WHOLE FOOT is a pump ! ( almost )

After a lot of reading on the subject it is starting to look to me like almost the entire foot is an "oseofasical pump " dependent for its power on the changing shape of the osseous components of the foot during weight acceptance .

As weight is accepted onto the reference foot during gait , the medial and lateral longitudinal arches and the transverse arch are compressed , leading to increased tension in the interconnected deep and superficial fascial structures that envelop the foot . This increase in tension causes compression of the soft tissues of the foot including most of the venous system , dorsal and plantar .

Fox and Gardner produce interesting before and after pictures of the coupled drainage of the dorsal and deep plantar venous components of the foot , see below. ( Note the almost total expulsion of blood from the venous components of the foot between the weight bearing and none weight bearing conditions) . The fascially related , coupled drainage of the plantar and dorsal aspects of the foot mean that perforator veins need not have valves .

On the plantar aspect of the foot ,when the bony arch of the foot is compressed and the fascia stretched ,the muscular tissues between the two are compressed and this force is transmitted to the plantar veins causing them to empty . However , Fox and Gardner found that the plantar foot pump (in my opinion one part of a greater whole ) could operate in less effective fashion in the paraplegic foot , presumably because the fatty infiltrate that replaces much of the plantar intrinsic musculature in such feet is a less effective transmitter of force . But it did still function .

The pressure generated by the foot , an osseofascial pump , increases with increased ground reaction forces allowing venous return from the foot to be maintained as centrifugal effects increase .

The venous pump of the human foot--preliminary report. - NCBI
by AM Gardner - ‎1983 - ‎Cited by 169 - ‎Related articlesBristol Med Chir J. 1983 Jul;98(367):109-12. The venous pump of the human foot--preliminaryreport. Gardner AM, Fox RH. PMCID: PMC5077034.