MUSCULAR SVSTEiM. 117 



Actiufi. — They seem to be for the purpose of contracting the 

 dimensions of the thoracic cavity. 



5— DORSO-COSTAL REGION. 



SUPERFICIALIS-COSTARUM. DorSO-COStailS. 



Situation. — Spread over the back. 



Figure. — Broad, thin, digitated, irregular. 



Attachmeut. — Superiorly, to the ligamenturn nuchee in its ex- 

 tension through the back and loins : inferiorly, to the posterior 

 borders, below their angles, of the 6th and all the ribs behind it. 



Relations. — Externally, with the panniculus; anteriorly, with 

 the serratus ; internally, with the transversalis costaruiii, and 

 longissimus et spinalis dorsi ; inferO-posteriorly, with theobliquus 

 externus abdominis. 



Structure. — Consisting of a thin ajjoneurosis, superiorly ; from 

 which originates eleven or twelve broad fleshy digitations : most 

 of them (all the posterior ones) possessing thin tendinous cover- 

 ings. The aponeurosis itself serves as a faschia to the muscles 

 underneath it. 



Direction. — Downwards \ with a slight inclination forwards. 



TRANSVERSALIS cosTARUM. — Trachelo-costalis. 



Situation. — Upon the supero-laterai parts of the thorax. 



Form. — Elongated ; half penniform : broad in the middle; nar- 

 rowing towards either extremity. 



Attachment. — Posteriorly, to the anterior borders of the ribs, 

 near to the spine ; and to the posterior edges of their angles : an- 

 teriorly, to the transverse process of the last cervical vertebra. 



Relations. — Externally and inferiorly, with the last muscle ; 

 internally, with the costal arches ; superiorly, with the longissi- 

 mus dorsi. 



Direction. — Longitudinal : inclining downwards. 



Structure. — Complicated. Consisting of two sets of tendons : 

 one set embedded in fleshy fibres, and serving to strengthen its 

 attachment superiorly ; the others are external, distinct from 

 the fleshy parts, are flat and elongated, broad in the middle, grow- 

 ing longer and more slender as they approach the extremities, 

 and are fixed to the costal arches. A separate tendon extends to 

 the cervical vertebra in front. 



Action. — To elevate the ribs, and thus produce some enlarge- 

 ment of the cavity of the thorax. 



L E V A TO RE s c o s T A K I M . — Transverso-costales . 

 Number. — About fifteen. 

 5'?V//rt/?o;?.— -Deep-seated ; upon the back. 



