FASCIA AND SUPEKFICIAL MUSCLES OF THE BACK. 365 



of a group acting more or less in harmony with, and antagonised by, other and 

 opposite groups. 



DESCRIPTION OF THE MUSCLES. 



The skeletal muscles may be divided into two series : axial and appendicular. 

 The axial muscles comprise the muscles of the trunk, head, and face, including 

 the panniculus carnosus (platysma). These muscles are more or less segmental 

 in arrangement, and are grouped around the axial skeleton. The appendicular 

 muscles, the muscles of the limbs, are grouped around the appendicular skeleton. 

 They are not segmental in arrangement, they are morphologically separate from 

 the axial muscles, and they are arranged in definite strata in relation to the bones 

 of the limbs. 



APPENDICULAR MUSCLES. 



THE UPPER LIMB. 



FASCIAE AND SUPERFICIAL MUSCLES OF THE BACK. 



Fasciae. 



The superficial fascia of the back presents no peculiarity. It is usually 

 of considerable thickness, and contains a quantity of fat. 



The deep fascia closely invests the muscles. It is attached in the median 

 plane of the back to the ligamentum nuchae, supraspinous ligaments, and vertebral 

 spines ; laterally it is attached to the spine of the scapula and to the clavicle, and 

 is continued over the deltoid region to the arm. In the neck it is attached, 

 above, to the superior nuchal line of the occipital bone, and is continuous, laterally, 

 with the deep cervical fascia. Below the level of the shoulder it is continuous, 

 round the border of the latissimus dorsi muscle, with the fascia of the axilla and 

 of the abdominal wall. In the back and loin it constitutes the fascia lumbodorsalis 

 or aponeurosis of the latissimus dorsi. This layer conceals the sacrospinalis 

 muscle, and is attached medially to the vertebral spines, and laterally to the angles 

 of the ribs, and to the iliac crest. 



The Superficial Muscles of the Back. 



The muscles of the back are arranged in four series according to their attach- 

 ments: (1) vertebro-scapular and vertebro-humeral; (2) vertebro-costal; (3) vertebro- 

 cranial ; and (4) vertebral. The first of this series consists of the posterior muscles 

 connecting the superior extremity to the trunk, and comprises the first two layers 

 of the muscles of the back (1) trapezius and latissimus dorsi, and (2) levator 

 scapulae and rhomboidei (major and minor). The deeper (axial) muscles of the 

 back are dealt with later (p. 437). 



M. Trapezius. The trapezius is a large triangular muscle which lies in the 

 upper part of the back. It arises from the superior nuchal line of the occipital 

 bone in its medial third, from the external occipital protuberance (Fig. 396, 

 p. 444), from the ligamentum nuchse, from the spines of the seventh cervical and 

 all the thoracic vertebras, and the intervening supraspinous ligaments. The origin 

 is by direct fleshy attachment, except in relation to the occipital bone, the lower 

 part of the neck, and the lower thoracic vertebrae, in which places the origins are 

 tendinous. 



From their origins the muscular fibres converge towards the bones of the 



shoulder, to be inserted continuously from before backwards as follows : (1) The 



I occipital and upper cervical fibres into the posterior aspect of the clavicle in its 



lateral third (Figs. 327, p. 366, and 329, p. 368); (2) the lower cervical and 



Kper thoracic fibres into the medial border of the acromion, and the upper 

 rder of the spine of the scapula; and (3) the lower thoracic fibres, by a 



