118 MUSCULAR SYSTEM. 



Figure. — Flattened; conoid: bases turned downwards. 



Attachment. — Superiorly, to the transverse processes of the 

 dorsal vertebrae : interiorly, to the anterior borders of the ribs, in 

 the spaces between their tubercles and angles. 



i?e/a/20ws. — Externally, with the longissimus dorsi ; internally, 

 with the ribs. 



Direction. — Oblique : from before backwards, and from above 

 downwards. 



Structure. — Consisting of bundles of fleshy and tendinous 

 fibres, having a similar arrangement to, and looking like the 

 heads or beginnings of, the external intercostals. Their superior 

 ends are interwoven with small compact tendons, whence proceed 

 tendinous slips, which intersect their fleshy bellies. Their inferior 

 parts are enveloped in aponeuroses, which become thin and va- 

 nish upon their surfaces. The middle bundles are thickest and 

 longest: the anterior ones are but scanty; and the three or four 

 foremost ribs are entirely destitute of them. 



Action. — To assist in the elevation of the ribs. 



6.— DORSAL REGION. 



Including muscles connected with the vertebrae of the back. 

 Lo N GissiM u s DO RSI. — IHo-spinalis. 



Situation. — Upon the supero-lateral parts of the back and loins. 



Figure. — Broad, thick, and elongated. 



Attachment. — Posteriorly, to the crista of the ileum, to the 

 side of the sacrum, to the spinous and transverse processes of all 

 the lumbar vertebrae, and to the spinous processes of the six pos- 

 terior dorsal : anteriorly, to the angles of the twelve posterior 

 ribs, to the transverse processes of all the dorsal vertebrae, and to 

 those of the three or four hindermost cervical. 



Relations. — 'Externo.Wy and inferiorly, with the superficialis cos- 

 tarum ; internally, with the ribs and vertebrae ; superiorly, with 

 the spinalis dorsi. 



Direction. — Longitudinal ; inclining downwards, as well as 

 forwards. 



Structure. — This muscle (one of the longest and, at the same 

 time, most bulky muscles in the body) is constituted of a dense 

 and strong aponeurosis ; a thick, long, and uniform fleshy belly ; 

 and several broad and flat tendons intimately connected with 

 the fleshy parts. The aponeurosis completely invests the lum- 

 bar portion of the fleshy belly ; with the fibres of which it is 

 so intimately adherent, that the two are inseparable by the knife 

 from one another. From this, the aponeurosis is continued up- 

 wards, to be fixed to the spines of the vertebrae ; and forwards, 

 to be spread over the dorsal division of the muscle, upon which 



