PECTORALIS MAJOR. 203 



downwards and outwards, and is inserted into the base of the scapula 

 opposite the triangular surface at the commencement of the spine. 



The rhomboideus major, three or four times broader than the pre- 

 ceding muscle, arises from the spinous processes of the four or five 

 upper dorsal vertebrae, and their interspinous ligaments, and is inserted 

 into that part of the base of the scapula which is included between 

 the spine and inferior angle. Some of the fibres, instead of being fixed 

 to the bone, end in a tendon which is connected to the scapula above 

 the lower angle ; and, in consequence of this arrangement, the muscle 

 may, in part, be separated from the bone without division of its muscular 

 or tendinous fibres. 



The greater part of the rhomboidei muscles is covered by the trapezius, a small 

 angular portion of the rhomboideus major only lying superficially in the interval 

 between the trapezius and latissimus dorsi ; the extent of this portion varies with the 

 position of the scapula, being increased when the arm and shoulder are raised from 

 the side. The rhomboidei cover the greater part of the serratus posticua superior, 

 and the posterior scapular artery descends on their deep surface. 



The levator anguli scapulas, arises by slightly tendinous slips from the 

 posterior tubercles of the transverse processes of the first four or five 

 cervical vertebrae, between the splenius and scaleni muscles, and forms an 

 elongated fleshy mass which is inserted into the portion of the base of the 

 scapula intervening between the spine and superior angle. 



The number of vertebral attachments of the levator anguli scapulae is subject to 

 some variation. A slip has been observed to extend to it from the mastoid process of 

 the temporal bone (Theile), and from the second rib (Meckel). It often appears as a 

 divided muscle, the parts connected with the several vertebrae remaining separate, 

 even to the place of insertion. In quadrupeds it is united with the serratus magnus, 

 so as to form a single muscle. 



MUSCLES ATTACHING THE UPPER LIMB TO THE TRUNK ANTERIORLY. 



The pectoralis major muscle arises from the sternal half, or a little more, 

 of the clavicle ; from the anterior surface of the sternum, extending as far 

 down as the insertion of the cartilage of the sixth rib ; from the cartilages 

 of the first six ribs, and also the bony part of the sixth rib ;. and from the 

 aponeurosis of the external oblique muscle of the abdomen. Springing 

 from this extensive origin its fibres form a thick mass, and, converging to 

 some extent, are inserted by a tendon of considerable breadth into the ridge 

 which forms the outer margin of the bicipital groove of the humerus, and 

 thence downwards as far as the deltoid impression. The muscular fasciculi 

 converge towards the axilla, and the muscle with its tendon is folded at 

 the axillary border, so that the clavicular part remains in front, while the 

 pectoral part passes behind. The arrangement is such that at last the 

 folded tendon of the muscle is inserted into the humerus in two nearly 

 parallel lines which are connected below. The fibres of the clavicular part, 

 in the order of their origin from without inwards, are prolonged into the 

 anterior or outer line of insertion in order from above downwards. The 

 pectoral part of the muscle is inserted into the inner or posterior line ; 

 the fibres which have the highest origin being the lowest at their 

 insertion, and those which arise lower in succession from the chest 

 passing higher and higher to their insertion on the humerus. Further, 



