The arch is exaggerated and the instep abnormally high; there is hyper-extension of the toes at the metatarso-phalangeal joints, and plantar-flexion at the inter-phalangeal joints; the plantar fascia and muscles are shortened.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition."
Alexander Miles Alexis Thomson
Mechanically, it acts as a stay when the animal is standing by maintaining the metacarpo-phalangeal angle.
"Diseases of the Horse's Foot"
Harry Caulton Reeks
Above, it is in connection with the synovial membrane of the pedal articulation and that of the metacarpo-phalangeal sheath.
"Diseases of the Horse's Foot"
Harry Caulton Reeks