§ I.
1. The rotula, a sort of bony production of the sesamoid kind, attached
to the tendon common to the extensors of the leg, represents a moveable
pulley, intended to slide on that formed by the separation of the
condyls of the os femoris. It protects the joint which it covers,
and, in point of structure, use, and situation, greatly resembles the
olecranon, from which it differs only in this, that, instead of being a
continuation or process of the tibia as the olecranon is of the ulna,
it is only attached to that bone by a strong and thick ligament which
is inserted into its tuberosity. Hence it follows, that between the
injuries of the one and the other, there must be a great analogy: and
indeed most of the signs characteristic of fractures of the olecranon,
are characteristic also of those of the rotula, and the treatment
which, in such cases, is suitable for the former, differs but little
from that required by the latter.
§ II.