_a_, Subscapular fossa; _b_, _b_, _b_, muscular lines; _c_, _c_,
limiting line between subscapular fossa and serratus area; _d_,
glenoid cavity; _e_, _f_, tuberosity; _g_, nutrient foramen.
(Ellenberger-Baum, Anat. d. Hundes.)
]
The =scapula= is relatively long and narrow. The spine increases
gradually in height from above downward and divides the external surface
into two nearly equal fossæ. Its free edge is thick and rough above, and
at the lower part is thin and bent backward. The =acromion= is short and
blunt and is opposite the rim of the glenoid cavity. The subscapular
fossa is very shallow and is marked by rough lines. The rough area above
it for the attachment of the serratus magnus is large and quadrilateral
in front, narrow and marginal behind. The anterior border is thin,
strongly convex, and sinuous. The posterior border is straight and
thick. The vertebral border is convex and thick and bears a band of
cartilage. The cervical angle is rounded. The dorsal angle is thick and
square. The neck is well defined and bears a rough eminence posteriorly.
The glenoid cavity is continued forward upon the lower face of the
scapular tuberosity, which is blunt and bears no distinct coracoid
process. There is a rough eminence on the posterior surface of the neck,
from which the long head of the triceps arises. The cervical angle is
opposite the first thoracic spine, the dorsal angle lies above the
vertebral end of the fourth rib, and the articular angle at a point just
in front of the sternal end of the first rib in the ordinary standing
position. The shoulder has a great range of movement on the chest-wall.
The =humerus= is relatively very long, rather slender, and has a slight
spiral twist. The shaft is somewhat compressed laterally, especially in
its upper two-thirds; this part is curved in varying degree, convex in
front. The deltoid tuberosity has the form of a low ridge, and it is
continued by a crest which runs upward and backward and bears a tubercle
on its upper part. Another line runs from it down the anterior aspect
and forms the inner boundary of the very shallow musculo-spiral groove.
The nutrient foramen is about in the middle of the posterior surface. A
slight elevation on the proximal third of the inner surface represents
the teres tubercle. The head is long and strongly curved from before
backward. The neck is better marked than in the horse. The undivided
external tuberosity is placed well forward and extends little above the
level of the head. The internal tuberosity is small. The bicipital
groove is undivided and is displaced to the inner side by the extension
forward of the external tuberosity. The distal end bears an oblique
trochlear articular surface for articulation with the radius and ulna,
the outer part of which is the more extensive and is faintly grooved.
The epicondyles are prominent. The coronoid and olecranon fossæ often
communicate through a large =supratrochlear foramen=.
[Illustration: