358 ■ ABRAM T. KERR 



Schumacher found the fifth, sixth, seventh, eighth cervical 

 and first thoracic 7 times and the fifth, sixth, seventh and eighth 

 cervical nerves 3 times out of 10 cases. 



In comparing my findings with those given above, I can only 

 refer again to what I said concerning the first thoracic nerve 

 when discussing the posterior fasciculus of the plexus. 



THE AXILLARY NERVE 



The axillary nerve (circumflex) is usually described as one of 

 the terminal branches of the posterior fasciculus of the brachial 

 plexus. 



As noted in connection with the radial nerve, this is the con- 

 dition found in 138 of the 173 satisfactory records in my series, 

 or in 79.76 per cent. In 67 of these, or 38.72 per cent, the axil- 

 lary is a single nerve (fig. 2) ; in 57, or 32.94 per cent, it gives off 

 the axillary subscapular nerve to the teres major and axillary 

 border of the subscapularis muscles (fig. 1) ; in 6 it gives off both 

 the axillary subscapular nerves and the thoracodorsal nerve 

 (fig. 6); in 4 it gives off the axillary subscapular and another 

 separate branch to the axillary border of the subscapularis 

 muscle (fig. 3); in another the axillary subscapular nerve and 

 two additional branches to the subscapularis muscle; in 2 others 

 both the axillary subscapular and thoracodorsal and a branch 

 to the subscapularis muscle; and in another it gives off a branch 

 to the axillary subscapular nerve. 



In 35 of the 36 plexuses where there is no posterior fasciculus, 

 the record for the axillary is satisfactory. In 16 of these it 

 arises from a cord formed by the union of the dorsal branches 

 of the cephalic and intermediate trunks (fig. 6). In 6 of these 

 it is single, in 9 it gives off the axillary subscapular nerve, and in 

 one both the axillary subscapular and the thoracodorsal nerve. 



In 16 other cases of this group it arises from the dorsal division 

 of the cephalic trunk (fig. 7). In 3 of these the dorsal division of 

 the cephahc trunk is formed by the union of the dorsal divisions of 

 the fifth and sixth cervical nerves. In 7 of these it is single, and 

 in 8 it gives off the axillary subscapular nerve. In one of these 

 it receives a small branch from the axillary subscapular nerve. 



