192 MUSCLES OF THE UrPER LIMB. 



The rhomboideus minor, a comparatively narrow muscle, arises 

 from the spinous processes of the seventh cervical and first dorsal 

 vertebra and from the li.o-amentum nucha). It inclines 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, much broader than the preceding muscle, 

 lies immediately Ix'low and in contact with it. It arises from the 

 spinous processes of the four or five upper dorsal vertoi)ra3 and their 

 interspinous ligaments, and is inserted into that ])art of the base of the 

 scapula which "is included between the spine and inferior angle. A 

 considerable part of the attachment at the insertion is only by firm 

 connective tissue, and the most of the fibres, instead of being fixed 

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

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

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

 cular or tendinous fibres, and must therefore act most immediately on 

 the lower angle. 



Ih'latlons. — The greater part of the rhomhoidei muscles is covered by the 

 trapezius, a small angular portion only of the rliomljoideus major being sub- 

 cutaneous in the interval between the trapezivxs 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 sen-atus posticus superior, and the posterior scapular arteiy descends 

 on their deep surface. 



Varieties. — Both rhomboid muscles are liable to variations in the extent of 

 their vertebral and scapular attachments. An additional muscle has been observed 

 running close and parallel to the upper border of the minor, from the scapula to 

 the occipital bone, and has been called rhomboideus vcc'q'ittdis after a similar 

 muscle occurring in some animals. 



The levator anguli scapulas arises by slightly tendinous slips 

 from the posterior tubercles of the transverse processes of the four 

 or five upper cervical vertebra, between the attachments of the 

 splenius and scaleni muscles, and forms an elongated fleshy mass which 

 is inserted into the base of the scapula from the spine to the superior 

 angle. 



Varletiex. — The number of veitebral attachments of the levator anguli 

 scapula? is sul^ject to some variation. A slip has been observed to extend to it 

 from the occipital or 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 vertebraj remaining separate, even to the place 

 of insertion. It is occasionally connected by slips with the trapezius, scalene, 

 or serrated muscles. In quadrupeds it is united with the serratus raagnus, so as 

 to fonn a single muscle. 



Nerves of the preceding muscles. — The trapezius muscle receives its nerves 

 from the spinal accessory which enters it on the deep surface, after being 

 joined by branches from the third and fourtli cervical nerves, from these nerves 

 directly, and probably also from the posterior branches of the ceiwical and 

 dorsal spinal nerves as they pierce it. The latissimus dorsi is chiefly supplied 

 bv the long subscajuilar nerve of the brachial plexus, but may also receive twigs 

 from the dorsal and lumbar nerves which pass through it. The ner\'es of the 

 rhomboid muscles proceed in one or sometimes two branches from the fifth 

 cervical, and the levator scapula) is supplied from the third, and sometimes 

 also from the fifth, cervical nei-ves. 



