10 GUIDES FOR VERTEBRATE DISSECTION 



backwards to its insertion on the inside of the lower jaw behind 

 the temporalis. 



The masseter major is easiest traced from its insertion on the 

 outside of the lower jaw opposite the temporalis to its origin from 

 the tympanic annulus and the squamosal. The masseter minor 

 is attached to the hind end of the jaw and to the quadratojugal. 



Sketch these muscles, tympanum, etc., in side view. 



The rhomboideus anterior muscle extends, on the dorsal 

 surface of the body, from the dorsal fascia and the fronto-parietals 

 back to its insertion on the ventral surface of the suprascapula. 

 The anterior part of the dorsal surface of the scapula and supra- 

 scapula is covered by the dorsalis scapulas muscle, the fibres of 

 which converge to their insertion on the crista deltoidea. Behind, 

 the scapular elements are covered by the latissimus dorsi muscle, 

 which also extends back on to the back itself. It arises from the 

 dorsal fascia and its fibres unite above the shoulder with those 

 of the dorsalis scapula. Lateral to and deeper than the rhom- 

 boideus anterior is the levator scapulae anterior, the anterior end 

 of which is covered by the cucularis, while behind it is inserted 

 on the ventral surface of the suprascapula. 



Sketch these muscles. 



Next cut the rhomboideus anterior and the latissimus dorsi 

 and attempt to lift the suprascapula. It will be found to be 

 held by several muscles, most prominent of which are the 

 rhomboideus posterior, visible in part on the medial side of the 

 suprascapula, and the serratus superior, which overlies the postero- 

 lateral portion of the rhomboideus posterior. 



Draw these, then remove them and the suprascapula, exposing 

 the large longissimus dorsi muscle, which extends from the 

 occipital region of the skull back to the pelvis and to the anterior 

 third of the urostyle. Is it attached to any of the vertebrae? 

 Does it present inscriptiones tendinise? Is it attached behind to 

 other parts than the urostyle? 



Behind and lateral to the longissimus dorsi is the coccygeo- 

 iliacus muscle, extending from the posterior part of the urostyle 

 to the iliac bone. The other and deeper muscles of the back may 

 be omitted. 



Aside from the muscles from the shoulder-girdle region already 

 mentioned, there is but a single muscle, the triceps brachii or 

 anconseus, in the upper arm. This has four heads (scapularis, 



