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THE OSTEOLOGY AND MYOLOGY 



comes almost to a point above. Its insertion, by a short, stout, flattened tendon, is ordina- 

 rily into the extremity of the occipital crest, and therefore into the squamosal ; but some- 

 times into the mastoid just underneath this point. In most of its course it is in relation 

 externally with the levator anguli scapukc ; internally it lies upon the complcxus. 



Rectus capitis posticus major. — Of large size, much surpassing the other rectus, though 

 in turn surpassed by the obliquus inferior. It is a stout, thick, fleshy band, arising from 

 the side of the extended curved upper margin of the spinous process of the axis, and cor- 

 responding part of the third cervical spine, extending outward as it passes forward (but not 

 so obliquely as the obliquus inferior) to be inserted fleshy into the greater part of the 

 depressed occipital space — all that portion of the bone between the rectus minor and corn- 

 plexus, from near the median line of the skull to the insertion of the obliquus superior. 



Rectus cajntis posticus minor. — ^Very much smaller ; perfectly distinct ; a little flattened, 

 fleshy band, in apposition with its fellow, running straight from atlas to occiput ; arising 

 from the whole of the posterior border of the atlas-ring, from median line to base of trans- 

 verse process ; inserted into the occipital depression, just below the foregoing muscle. 



Obliquus superior. — A small muscle, perfectly straight in its course ; arising from the 

 tip, anterior border, and most of under surface of the transverse process of the atlas, in 

 relation in front with the rectus lateralis ; inserted fleshy into the side of the base of the 

 occiput, between the extremity of the crest and the root of the paroccipital process. 



Obliquus inferior. — As was to have been anticipated, viewing the great size of the axial 

 spine, and transverse production of the atlas, this muscle is of great extent and power. It 

 is the only one of the four at the base of the skull that is decidedly oblique to the long 

 axis of the neck. It arises fleshy from the whole of the expanded side of the axial spine, 

 and is further prolonged in a point upon the side, near the tip, of the spines of the third, 

 fourth and fifth cervicals ; fills the deep longitudinal fossa along these vertebme, passes very 

 obliquely outward and forward, lying upon the surface of the atlas, between this and the 

 rectus major, and is inserted into the margin, lower edge of base, and upper surface of 

 the transverse process of the atlas. Its divarication from its fellow leaves a broad, triangu- 

 lar space in which the recti majores are seen. This muscle, with the great rectus, might 

 together be almost mistaken, at first glance, for the complcxus itself. 



Muscles of the Thorax. 



Most of the muscles lying upon the chest proceed to, or come from other parts, and are 

 considered in other connections. This leaves only the following to be described under this 

 head: — serratus superior and inferior ; "sterno-costalis ;" triangularis stcrni ; intercostales 

 externi and mterni ; infracostales ; levatores costarum ; and the diaphragm. 



Serratus posticus superior. — A muscle of large size, arising by a continuous aponeurotic 

 lamina from the transverse process of the sixth (seventh?) cervical vertebra, and first two 

 ribs ; and by fleshy digitations from the third — ninth ribs ; inserted into the spinous pro- 

 cesses of corresponding vertebrae. The direction of the fibres from the spine is obliquely 

 outward and downward. In its upper portion, fleshy fibres almost reach the spine ; below, 

 the aponeurosis of attachment grows broader. The last fleshy fasciculus is very short, and 

 interdigitates with one from the obliquus abdominis, about two inches from the spine. 



Serratus posticus inferior. — The direct downward continuation of the plane of the fore- 



