Mc.III, Large metacarpal bone; Ph.I, first phalanx; Ph.II, second
phalanx; Ph.III, third phalanx; 1, deep flexor tendon; 2, band from
first phalanx to plantar cushion. (After Schmaltz, Atlas d. Anat. d.
Pferdes.)
]
=Movements.=—These are of the nature of flexion and extension, the axis
of motion passing through the upper attachments of the lateral
ligaments. In the ordinary standing position the joint is in a state of
partial =dorsal flexion=, the articular angle (in front) being about
140° to 150°. (In the hind limb it is about 5° greater.) Diminution of
this angle (sometimes termed “overextension”) is normally very limited
on account of the resistance offered by the sesamoidean apparatus, but
it varies considerably in amount in different subjects. =Volar flexion=
is limited only by contact of the heels with the metacarpus. During
volar flexion a small amount of lateral flexion is possible.