J44 THE EXTERIOR OF THE HORSE. 



into a restrained position for the performance of a surgical operation, castration, 

 for example ; thus may be produced an accident which, if it is not a fracture 

 properly speaking, simulates it by its deformity and by its results." l 



CHAPTER II. 



ANTERIOR EXTREMITY OF THE BODY. 



A. The Breast, or Pectoral Region. 



Situation; Limits; Anatomical Base. The breast is a 

 symmetrical region situated at the anterior part of the trunk, and 

 limited in front by the inferior border of the neck, behind by the 

 axillce and the inter-axillary region, and on each side by the arm. 



It has for its main osseous element the anterior extremity of the 

 sternum, on which are inserted the sterno-hyoideus, sterno-thyroideus, 

 sterno-maxillaris, and sterno-humeralis muscles, and these are separated 

 from the internal face of the skin by an abundance of connective tissue. 

 It contains the plate vein, situated in the gutter formed by the adjoining 

 borders of the sterno-humeralis and mastoido-humeralis muscles, which 

 can be located easily from the exterior, and on which phlebotomy is 

 sometimes practised. 



Form. The configuration of the external surface of the pectoral 

 region varies according to the subject, from the fact that the volume 

 of the above-mentioned muscles leaves the trachelian appendix of the 

 sternum more or less prominent. But little attention need be given 

 to this prominence. Nevertheless, if it is very marked, the region is 

 qualified as sharp. Sometimes the breast presents two deep depressions 

 situated within the scapulo-humeral angles ; these depressions are due to 

 a meagreness of the muscles or to a change in the direction of the 

 scapulo-humeral angle. This peculiarity is very common in horses 

 which are poorly developed, and the breast is then described as hollow, 

 or sunken. 



Width. The width is the principal element to be considered in 

 the examination of the breast, and, as Bourgelat has said, it should be 

 proportional to the volume of the body or the general development of 

 the animal. 



1 H. Bouley, loc. cit. 



