348 MUSCLES OF THE BACK. 



2. Coccygeus. 



Arises, tendinous and fleshy, from the spinous process of the 

 OS ischium, and covers the inside of the posterior sacro-ischiatic 

 ligament ; from this narrow beginning, it gradually increases 

 to form a thin fleshy belly, interspersed with tendinous fibres. 



Inserted into the extremity of the os sacrum, and nearly the 

 whole length of the os coccygis laterally. 



Use. To support and move the os coccygis forwards, and to 

 tie it more firmly to the sacrum. 



Muscles situated on the Posterior Part of the TrunJc. 



These may be divided into four layers and a single pair. 

 The first layer consists of two muscles, which cover almost 

 the whole posterior part of the trunk. 



Trapezius seu CucuUaris, 



Arises, by a strong round tendon, from the lower part of the 

 protuberance in the middle of the os occipitis behind ; and, by 

 a thin membranous tendon, which covers part of the 

 splenius and complexus muscles from the rough curved line 

 that extends from the protuberance towards the mastoid 

 process of the temporal bone ; runs down along the nape of 

 the neck, where it seems to arise from its fellow, and covers 

 the spinous processes of the superior vertebrae of the neck ; it 

 rises from the spinous processes of the two inferior cervical, and 

 from the spinous processes of all the vertebrae of the back : 

 adhering tendinous, to its fellow, the ivhole length of its origin. 

 The junction of the tendons form a sort of elliptical expansion 

 on the back of the neck. 



Inserted, fleshy, into the posterior half of the clavicle ; 

 tendinous and fleshy, into the acromion, and into almost all 

 the spine of the scapula. 



Use. Moves the scapula according to the three difl^erent 

 directions of its fibres : for the upper descending fibres draw it 

 obliquely upwards ; the middle transverse straight fibres draw 



