ANATOMY IN A NUTSHELL. 



459 



The attachment of this muscle varies not only in different bodies but on the 

 opposite side of the same body. The superior fibers pass vertically, its middle 

 fibers obliquely outward, and its lower fibers horizontally. 



Origin. — From the posterior surface of the ensiform cartilage and the 

 posterior surfaces of the sternal end of the costal cartilages of the three or four 

 lower true ribs, and also from the lower one-third of the posterior surface of 

 the sternum. 



Insertion. — Into the inner surface and lower border of the costal cartil- 

 ages of the second, third, fourth, and fifth ribs. 



Action. — Muscle of forced expiration. 



Nerve Supply. — Intercostal nerves. 



Blood Supply. — Intercostal arteries. 



PLATE CCXLVII. 



EMINENCE FOR SUP. 

 SEMI-CIRCULAR CANAL \ 

 SUP. SURF. OF PETROUS PORTld 

 FOR SUP. PETROSAL SINUS 



SQUAMOUS 

 PORTION. 



FOR LATER SINUS 



POST. SURFACE OF PFTROUS PORTION 



DEPRESSION FOR 

 CASSER1AN GANGLION. 



CAROTID CANAL 



' OPENING FOR SMALLER PETROSAL N. 



HIATUS FALLOPII 



INT AUDITORY MEATUS 



OPENINGFOR PROC.OF DURA-MATCR 



AQUEDUCTUS VESTIBULI 



The Petrous Portion of the Temporal Bone. 



Levatores costarum. — Description. — These muscles are situated between 

 the transverse processes of the seventh cervical vertebra and the eleven upper 

 dorsal vertebrae and the border of the first rib below them. There are twelve 

 on each side of the spine. 



Origin. — From the ends of the transverse processes of the seventh cervi- 

 cal and the eleven upper dorsal vertebra 1 . Their direction is obliquely down- 

 ward and outward. 



Insertion. — Into the upper bonier of the firsl rib below between the 

 tubercle and angle. In the lower Levatores costarum muscles there is a second 

 insertion to the second rib below its origin, thus where this is true each rib re- 

 ceives fibers from the transverse processes of the two vertebras. 



Action. — Muscle of inspiration. 



Nerve Supply. — Intercostal nerves. 



Blood Supply. — Intercostal arteries. 



