MUSCLES OF THE UPPER LIMB. 187 



I— MUSCLES AI^D FASCIA OF THE UPPER LIMB. 



A certain number of muscles situated superficially on the trunk ixass 

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

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

 of the muscles of the trunk, but considered with reference to their 

 destmation and action tliey may be held as beloncring to the upper 

 limbs, and will therefore be so described in the prc^scnt section. The 

 muscles referred to are, posteriorly, the trapezius, latissimus dorsi 

 the rhomboidei, and levator anguli scapulre ; and, anteriorly, the two 

 pectoral muscles, the subclavius, and the serratus mas^nus. Alon^^ with 

 these might also be included the clavicular part of the sterno-cleido- 

 mastoid muscle and the omohyoid ; but as these last have important 

 relations with parts situated in the neck, they are more conveniently 

 described among the muscles of that region. 



I. BETWEEN THE TRUNK AND THE UPPER LIMB POSTERIORLY. 



Fasciae. — The superficial fascia covering the muscles which pass 

 from the trunk to tlie shoulder and upper limb posteriorly forms a 

 layer of considerable strength with em))edded fat lying below 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 invest- 

 ing the superficial muscles to which it furnishes sheaths : at the outer 

 nwgms of the trapezius and latissimus dorsi muscles it is continuous 

 with the deep fascia3 of the neck, breast, axilla, 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 vertebra, 

 and dorsum of the sacrum, 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 lumdar cqwneurosis, to which tlie latissimus dorsi and other muscles 

 are attached posteriorly ; but this will be most conveniently described 

 along with the muscles of the back. 



Muscles. — The trapezius muscle (cucullaris) arises by a thin apon- 

 eurosis from the protuberance of the occipital bone, and the inner third of 

 Its superior curved line, from the ligamentum nuclide, and from the 

 spines of the last cervical and all the dorsal vertobra3, as well as from the 

 supraspinous ligaments. From this extended line of origin the fibres 

 converge to their insertion : the superior fibres, descending and turning 

 forwards m the neck, are inserted into the external 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 

 flat tendon which glides over the triangular area at the base of the spine 

 of the scapula, and is inserted into the rough mark at the roofc 

 of the spme. The greater part of the line of origin presents only 

 a small admixture of tendinous fibres, but opposite the seventh cervical 



