MUSCLES OF TUB TRUNK. 



261 



extended over the loins, back, and side of the thorax, and formed of an aponeu- 

 rotic and a muscular portion. 



The aponeurosis is attached, by its superior border, to the summits of the 

 spinous processes of all the lumbar, and the last fourteen or fifteen dorsal 

 vertebric — -Jixed inftp/iion of the muscle. 



The fibres of the fleshy portion are detached from the inferior border of the 

 aponeurosis, at the twelfth or thirteenth ribs, to the cartilage of the scapula. 

 They are directed forwards and downwards, and all convertre into a flat tendon 

 which is inserted into the internal tuberosity on the body of the humerus — 

 movable insertion. This tendon is remarkable, at its termination, for being 



Fig. 162. 



MUSCLES OF THE SPINAL REGION OF THE NECK, BACK, AND LOINS (MIDDLE LAYER) ; AND OF THB 

 COSTAL AND ABDOMI.VAL REGION (SUPERFICIAL LAVER). 



1, 2, Rhomboideus ; 3, annularis muscle of the scapula ; 4, ^^Jl]enius ; 5, its mastoid aponeurosis; 

 6, mastoid portion of the trachelo-mastoiJeus ; 7, its tendon; 8, cervical insertions of the 

 raastoido-humerilis; 9, atloideaa tendon common to the mastoido-humeralis, splenius, and 

 trachelo-mastoideus ; 10, great anterior straight muscle of the head; 11, inferior scalenus; 

 12, superior scalenus; 13, small anterior serratus ; 14-, posterior ditto; 15, serratus magnus; 



16, anterior fibres of the rectus abdominis, sometimes describe I as the transversalis costarum; 



17, one of the external intercostals ; 18, great oblique; 20, rectus abdominis; 21, stylo-maxillaris 

 portion of the digastric muscle. 



placed at the external face of the teres magnus or adductor of the arm, from 

 which it receives fibres, and between it and the lonf? extensor of the forearm ; 

 it then turns inwards, on the inferior extremity of the first, in such a manner 

 that this extremity is comprised within a duplicature of the membranous tendon 

 of the latissimus dorsi. 



Relations. — This muscle is covered by the skin, panniculus carnosus, dorsal 

 portion of the trapezius, and the mass of olecranian muscles. It covers the 

 infra-spinatus ; the cartilatre of the scapula ; the rhomboideus ; the anterior 

 and posterior serrated muscles, the aponeurosis of which is directly joined to its 

 own ; the longissimus dorsi ; the principal gluteal ; a portion of the external 

 surface of the last ribs, to which its aponeurosis strongly adheres ; as well as to 

 the corresponding external intercostals, and the serratus magnus. Between 

 the last rib and the external angle of the ilium, the aponeurosis unites with the 



