bone, the humerus (hum.) the distal end of which is deeply
excavated by the olecranon fossa (o.f.) as indicated by the dotted
lines; of two bones, the ulna (u.) and radius (r.) which are firmly bound
by ligament in the position of the figure (i.e., with the palm of the hand
downward, "prone"); of a number of small bones (carpalia), the carpus
(c.); of a series of metacarpals (mc.); and of three digits (= fingers)
each, except the first, or pollex, of three small bones-- the phalanges,
only the proximal of which appear in the figure. The ulna has a
hook-like head, the olecranon (o.) which distinguishes it easily from
the distally thickened radius. The limb is attached to the body through
the intermediation of the shoulder-blade (scapula, sc.) a flattened
bone with a median external ridge with a hook-like termination, the
acromion (acr.). There is also a process overhanging the glenoid
cavity (g.) wherein the humerus articulates, which process is called
coracoid (co.); it is ossified from two separate centres, and represents
a very considerable bone in the bird, reptile, and frog. Along the dorsal
edge of the scapula of the rabbit is unossified cartilage, which is
called the supra-scapula (s.sc.). In man there runs from the acromion
to the manubrium of the sternum a bone, the collar-bone or clavicle.
This is represented by a very imperfectly ossified rudiment in the
rabbit. The scapula and clavicle, the bones of the body connected
with the fore-limb, are frequently styled the pectoral girdle, or
shoulder-girdle; this name of girdle will appear less of a misnomer
when lower vertebrate types are studied.