LEVATOEES COSTAKUM AND SUBCOSTAL MUSCLES. 



321 



Corresponding in direction with the external intercostal muscles, into which they 

 are continued at their outer borders, they pass downwards and outwards, spreading 

 as they descend, and each is inserted into the outer surface of the rib belonging to 

 the vertebra below that from which it springs, between the tuberosity and angle. 

 The levator muscles belonging to the lower ribs present some longer additional fibres 

 which, passing over a rib, are inserted into the next one below ; these fibres are 

 sometimes distinguished as levator es costarum longiores. 



The levatores costarum lie in series superiorly with the middle and posterior scaleni, and 

 inferiorly with parts of the lateral lumbar intertransverse muscles. 



Fig. 288. DEEP MUSCLES OF THE ANTERIOR WALL OP THE THORAX, SEEN FROM BEHIND. 

 (Allen Thomson, after Luschka. ) J 



a, hack of manubrium ; 6, &, clavicles ; I to XI, anterior parts of eleven ribs and costal cartilages ; 



1, 1', sterno-thyroid muscles, that of the left side being cut short to show more fully the next muscle ; 



2, 2'. sterno-hyoids ; 3, 3, triangularis sterni ; 4, 4, upper part of transversalis abdominis, the right 

 and left muscles meeting at 4', 4', the back of the linea alba ; 5, attachments of diaphragm to the lower 

 ribs (the twelfth not represented in the figure), interdigitating with those of the transversalis ; 5', the 

 two slips to the ensiform process ; 6, 6, 6, internal intercostal muscles extending to the sternum, shown 

 in all the spaces on the right side, but only in the highest two of the left side ; 7, 7, 7, in the lower 

 spaces of the left side, the external intercostal muscles are seen, the internal having been removed. 



The subcostal muscles (transversus thoracis posterior ; fig. 289, 10) are small, 

 very variable slips lying on the inner aspect of the thoracic wall, in close connection 

 with the internal intercostals, and chiefly in the neighbourhood of the angles of the 

 ribs. They follow the same direction as the internal intercostal muscles, but their 



