THE MUSCLES AND FASCIAE OF THE UPPER LIMB. 203 



I. THE MUSCLES AND FASCIA OF THE UPPER LIMB. 



A certain number of muscles situated superficially on the trunk pass to the 

 bones of the shoulder and to the humerus, so as to attach the upper limb to the 

 body. These muscles, from their position, form a division of the muscles of the 

 trunk, but considered with reference to their destination and action they may be 

 held as belonging to the upper limb, and will therefore be so described In the present 

 section. The muscles referred to are, posteriorly, the trapezius,the latissimus dorsi, the 

 rhomboidei, and the levator anguli scapulas, and, anteriorly, the two pectoral muscles, 

 the subclavius, and the serratus magnus. Along with them might also be included 

 the clavicular part of the sterno-cleido-mastoid muscle and the omo-hyoid ; but as 

 these last have important relations with parts situated in the neck, they are more 

 conveniently described among the muscles of that region. 



BETWEEN THE TBUNK AND THE UPPER LIMB POSTERIORLY. 



FASCIAE. The superficial fascia covering the muscles which pass from the 

 trunk to the shoulder and upper limb posteriorly forms a layer of considerable 

 strength with embedded fat lying beneath the skin : it is continuous with that of 

 the neck above, that of the axilla and breast in front, and that of the abdomen and 

 hips below. 



The deep fascia of the back forms a dense fibrous layer closely investing 

 the superficial muscles to which it furnishes sheaths : at the outer margins of the 

 trapezius and latissimus dorsi muscles it is continuous with the deep fasciae of the 

 neck, axilla, breast, and abdomen, and turns round beneath the edges of the muscles 

 so as to complete their sheaths and separate them from the subjacent layer of 

 muscles. It is attached to the skeleton along the line of the spines of the vertebrae, 

 to the occipital bone, the spine of the scapula, and the crest of the ilium. 



In the loins there is a strong, flat, shining tendinous structure called the lumbar 

 aponeurosis, to which the latissimus dorsi and other muscles are attached posteriorly ; 

 but this will be most conveniently described along with the muscles of the trunk. 



MUSCLES. The trapezius muscle (cucullaris) arises by a thin aponeurosis from 

 the protuberance of the occipital bone, and the inner third of its superior curved 

 line, from the ligamentum nuchse, and from the spines of the last cervical and all 

 the dorsal vertebrae, as well as from the supraspinous ligament. From this 

 extended line of origin the fibres converge to their insertion : the superior fibres, 

 descending and turning forwards in the neck, are inserted into the outer third of the 

 clavicle at its posterior border ; the succeeding fibres pass transversely to the inner 

 border of the acromion process and upper border of the spine of the scapula ; while 

 the inferior fibres, ascending obliquely, terminate in a triangular flat tendon which 

 glides over the smooth area at the base of the spine of the scapula, and is inserted 

 into the rough prominence near the root of the spine. The greater part of the line 

 of origin presents only very short tendinous fibres, but opposite the seventh cervical 

 spine, and for the distance of several vertebrae above and below that point, a flat 

 tendon extends outwards, widest at the middle of the space and narrowing towards 

 the upper and lower ends, so that the aponeuroses of the two muscles taken together 

 have an elliptical form. The fibres of origin from the occipital bone have little or 

 no tendinous lustre. The muscles of the two sides have together the form of a 

 four-sided figure, or shawl or cowl, pointing downwards : hence the name of 

 cucullaris which has been given to it. 



