270 



ANATOMY IN A NUTSHELL. 



the tuberosity. The last two ribs, having no tuberosity, are developed each 

 by two centers. 



The peculiar ribs are the first, second, tenth, eleventh, and twelfth. They 

 respectively present the following peculiarities, viz: 



First Rib is broad, short, not twisted, has no angle, only one facet on 

 the head, but on its upper surface are seen two grooves for the subclavian 

 artery and vein, and between them a tubercle for the Scalenus anticus muscle. 



Second Rib is not twisted, its tuberosity and angle are very close to- 

 gether, and its upper surface presents rough surfaces for the Serratus magnus 

 and Scalenus posticus muscles. 



Tenth Rib has but one facet on its head. 



Eleventh Rib has no neck, no tuberosity, and but one facet on its head. 



Twelfth Rib has neither neck, angle, tuberosity nor groove, and but 

 one facet. 



Muscles of the Back. 



The muscles of the back are arranged in five layers. (Plates XVIII-CXI) 

 Those in the fourth layer get both the internal and external divisions of the 

 posterior 1 tranches of the spinal nerves. The external divisions supply those 

 in the third layer. The internal divisions together with the sub-occipital and 

 great occipital supply those in the fifth layer. (Plates XVIII-CXI.) 



First layer. 



1 Trapezius. See page 45. 



2 Latissimus dorsi. See page 52. 



Second layer. 



1 Levator angulae scapulae. Page 54. 



2 Rhombodideus minor. Page .1."). 

 :'> Rhomboideus major. Page 55. 



Third layer. 



1 Serratus posticus superior. 



2 Serratus posticus inferior. 



3 Splenius capitis. 

 I Splenius colli. 



Fourth layer. 



S \cr.\l AND LUMBAR REGIONS. 



1 Erector spina'. 



DORSAL REGION. 



2 Dio-costalis. 



.'5 Musculus accessorius ad ilio-costalem 

 I Longissimus dorsi. 

 5 Spinalis dorsi. 



I i.i;\ [CAL REGION. 



6 Cervicalis ascendens. 



7 Transversalia colli. 



8 Trachelo-mastoid. 

 !» Complexus. 



NERYKS. 



Spinal accessory; 3rd and 4th cervical. 

 Middle or long subscapular. 



3rd and 4th cervical; sometimes 5th. 

 5th cervical. 

 5th cervical. 



External divisions of the posterior 

 branches of the spinal nerves, in their 

 k spective regions. 



All the muscles in the fourth layer 

 get the external divisions of posterior 

 branches except the Spinalis dorsi and 

 Spinalis colli and the Complexus. 



They get the internal divisions of 

 the posterior branches. The Com- 

 plexus also gets the sub-occipital and 

 the great oc( ipital nerves. 



