Anatomy, Artistic; Animals in art; Zoological illustration
=Digitigrades=: =Cat=, =Dog= (Fig. 34).--In these animals the anterior
(cervical) border of the scapula is convex; the posterior (axillary)
border is straight or slightly concave. The supraspinous and
infraspinous fossæ are of equal extent (Figs. 35 and 36). The neck is
short. The spine of the scapula becomes more and more prominent towards
its inferior extremity, where it ends in a twisted and inflexed portion,
which represents the acromion process; this process terminates at the
level of the glenoid cavity. The coracoid process is represented by a
small tubercle, slightly curved inwards; this tubercle is situated
above the glenoid cavity, at the inferior part of the cervical border.
In the dog, the posterior angle, formed by the junction of the axillary
and the superior (spinal) borders, is obtuse; the spine rises
perpendicularly from the surface of the bone. The width of the scapula,
measured at the level of the spinal border (from A to A´, Fig. 35),
equals about half the length of the spine. We must, however, make an
exception for the turnspit dog, in which the superior border equals
three-fourths of that length. The scapula is, in this case, of a more
compact type; it is broader, but shorter. In the cat, the anterior
outline of the scapula, formed by the union of the cervical border and
the corresponding half of the spinal, is more convex; the posterior
angle is not obtuse, as in the dog. The spine is bent slightly downwards
and backwards; before terminating in the acromion process it presents a
triangular projection, the apex of which is directed downwards. The
tubercle which represents the coracoid process is curved inwards more
strongly than that of the dog, thus resembling more closely the
appearance of this process in the human being.
All proportions considered, the scapula of the cat is broader than that
of the dog; its width, measured along the length of its spinal border
(from A to A´, Fig. 36), equals three-fourths of the length of the
spine.
The clavicle is rudimentary; it is, however, better developed in the cat
than in the dog. The clavicle of the cat is represented by a small,
elongated bone, curved in outline, the convexity being turned forward;
it is united to the acromion and the sternum by ligamentous fibres; that
of the dog is merely a scale-like osseous plate situated on the
posterior surface of a muscle of this region (see Figs. 16 and 17).
The humerus is long and twisted in the shape of an S. The inferior
articular surface has the form of a simple pulley, for the condyle is
very slightly marked. The internal part of this articular surface
descends lower than the external; this condition resembles that found in
the human being, where the inner lip of the trochlea is lower than the
condyle.
In the dog, the olecranon fossa communicates with the coronoid by an
opening.
In the cat, there is a supra-epitrochlear canal (see Fig. 19), but no
olecranon perforation.
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