=The Pectoralis Minor= (Fig. 67, 6; Fig. 68, 8; Fig. 69, 11; Fig. 70, 12, 26).--This muscle, also called the _deep pectoral_, is, in animals, larger than the superficial pectoral, therefore certain authors prefer to give to this muscle and the preceding one the names of deep and superficial pectoral respectively. This nomenclature is evidently legitimate, and conforms more to reality, since it does not bring in the notion of dimensions which here is found in contradiction to nomenclature; but, in order to establish more clearly the parallelism with the corresponding muscles in man, we think it better, nevertheless, to give them the names by which it has been customary to designate them in connection with the latter. We will recall at the outset that the lesser pectoral muscle in man is completely covered by the great. In animals this is not the case; the lesser pectoral being very highly developed, projects beyond the great pectoral posteriorly, and occupies to a greater or less extent the inferior surface of the abdomen. It also consists of two parts: one anterior, which we designate by the name of _sterno-prescapular_; the other, posterior, bearing that of _sterno-humeral_.[20] [20] This division of the pectorals certainly complicates the nomenclature of these muscles; nevertheless, it introduces no insuperable difficulty from the mnemonic point of view. But where the study becomes less profitable, and comparison with the corresponding muscles in man more complicated, is in adopting the nomenclature of Bourgelat. Indeed, the great pectoral is designated by this author the 'common muscle of the arm and forearm,' while the lesser pectoral (or deep pectoral) is called the 'great pectoral' in its sterno-trochinian and 'lesser pectoral' in its sterno-prescapular portion. We do not consider it necessary to give the other theories relative to the homologies of these, notwithstanding the very real interest which they present from the purely anatomical point of view, as they have but few applications in the study of forms. The sterno-prescapular muscle, being covered by the sterno-humeral, has little interest for us. It arises from the sternum, and is directed towards the angle formed by the junction of the scapula and humerus; then it is reflected upwards and backwards, to terminate on the anterior margin of the shoulder by insertion into the aponeurosis, which covers the supraspinatus muscle. We can, especially in the horse after removal of the skin, recognise it, at the level of this region, in the interspace limited by the superficial muscles (Fig. 70, 26).