THORAX AND ABDOMEN OF THE HORSE 



65 



ligament (ligamentum costotransversarium dorsale) passes from the 

 dorsal surface of the vertebral transverse process to a roughened area 

 on the tubercle of the rib, and is closely applied to the capsule of the 

 joint. The ligament of the neck of the rib (ligamentum colli costse) 

 begins close to the cranial costal fovea of the vertebra and ends on the 

 roughened area on the dorsal aspect of the neck of the rib. 



Not infrequently, in the horse, the capitular and costo-transverse 



Lig. radiatum. y^y^ 



Lig. longitudinale 

 ventrale. 



Body of vertebra. 



I I M. intercostalis externus. 

 ' N. intercostalis. 



V. intercostalis. 



A. intercostalis. 

 Fig. 28. — The structures in an intercostal space, viewed from within. 



articulations are confluent in connection with the last, and sometimes 

 also the second last rib. 



Movements of the ribs have for their object an alteration in the 

 transverse diameter of the thorax. During the act of inspiration the 

 rib rotates about an axis that passes through the capitular articulation 

 and the joint between the rib-cartilage and the sternum, or an 

 equivalent point in the case of the asternal ribs. Seeing that, when the 

 thorax is in the condition of expiration, the rib is so placed that its 

 convexity inclines markedly backwards, it follows that if the rib be 

 acted upon by muscles in such a manner as to draw it forwards (that is 

 towards the head), rotation about the axis above-mentioned will cause 



