REPOET ON THE SPHENISCID^. 69 



Action. — This muscle elevates the sternal ribs, and acts as a muscle of inspiration. 



Belations.^lts origin is close to that of the sterno-trachealis, and is in contact with 

 the thoracic viscera. 



Nerve supply (?) 



Variations. — In Sj^heniscus magellanicus the insertion of the triangularis is limited 

 to the three anterior sternal ribs, while in Spheniscus demersus it is attached to five 

 of the latter. 



3. Levatores costarum. 



Leg vertebro-costaux, Vicq d'Azyr, 1774, p. 520, No. 3. 



Der ErUeber der Brust, Merrem. 



Levatores costarum, Tiedemarm, p. 299, No. 3. 



Ulevatenrs des cotes, Meckel, vol. vi. p. 16, No. 1. 



Levatores costarum, Owen, p. 29. 



Sur-eostaux, Gervais and Alix, p. 12. 



Attachments. — The levatores costarum form a series of small muscles, which are with 

 difficulty separable from the external intercostal muscles. They arise from the tips of the 

 transverse processes of all the dorsal vertebrae, except the last, as weU as from those of the 

 last cervical vertebra. Each levator costae is inserted into the anterior border of the 

 vertebral rib belonging to the succeeding vertebra, the insertion extending from the 

 tubercle to the point of attachment of the uncinate process, where its fibres blend with 

 those of the external intercostal muscle. 



The first and second levatores are scarcely separable from the fibres of the scalene 

 muscle, of which they seem to form a part. 



Action. — These muscles elevate the ribs, and act as muscles of inspiration. 



Relations. — They are concealed by the sacro-lumbalis. 



Nerve supply (?) 



4. External intercostal muscles. 



Les muscles intercostaux, Vicq d'Azyr, 1774, p. 520, No. 1. 



Die dussem Zwisehenrippeti-Muskeln, Tiedemann, p. 301, No. 6. 



Intercostaux externes, Meckel, vol. vi. p. 16, No. 2. 



Intercoitaitx externes, Cuvier, vol. i. p. 219. 



Intercostales externi, Owen, p. 31. 



Intercostales externi, Selenka, vol. vi. p. 104, No. 28. 



Intercostaux, Gervais and Alix, p. 13. 



Attachments. — These muscles are of considerable strength, and occupy the intervals 

 between the vertebral ribs. Their fibres arise from the posterior border of one vertebral 

 rib, and pass obliquely downwards and backwards, to be inserted into the anterior border 



