410 THE PBOCEEDINaS OF THE LINNEAN SOCIETY 



Legons d^Anatomie Comparee, torn. 2, p. 266 ; the author of 

 the article '^ Birds ^^ in Eees' Cydo^ocedia ; Owen in the article 

 " Aves " in Todd's Cyclopcedia, and in his Anatomy and Fhysiology 

 of the Vertebrata, Vol. II, p. 125), but in all cases somewhat 

 briefly and unsatisfactorily, and with not a few omissions of 

 important points. 



The Brachial Plexus consists in Aves of the whole of, or 

 of branches from, the anterior primary divisions of from three 

 (Todirhamphus sancfcus, Myzantha garrula), to five (Phalacroco= 

 rax ISTovEe-HoUandse, Grallina picata) spinal nerves, four being 

 the commonest number. The most general arrangement of the 

 plexus and its branches is as follows : — 



The first nerve before joining with any of the others detaches 

 a considerable branch, which subdivides for the supply of the 

 rhomboid and trapezius muscles. The second nerve also gives 

 off a branch before joining the plexus ; this is a slender twig 

 which runs directly backwards over the posterior nerves of the 

 plexus to supply the serrati muscles ; it is thus analogous to the 

 " nerve of Bell " of human anatomy. The second nerve of the 

 plexus divides into two ; the anterior of the two divisions is 

 joined by the first nerve to form the posterior brachial nerve 

 {circumflex and i/nusculo- spiral^; the posterior division joins with 

 the remaining two or three nerves to form the anterior brachial 

 nerve {ulnars median, and musculo-cdaneous). There are thus 

 formed two main nervous trunks, which, while in the neighbour- 

 hood of the axilla, give off a number of muscular branches. The 

 posterior brachial nerve gives branches to the subclavius, (^^ 

 coraco-brachialis brevis, (^^ and subscapularis, ^^^ to the teres 

 major, (*) and latissimus dorsi. The anterior brachial nerve 

 gives origin to two large branches for the pectoralis major, 

 one for the coraco-brachialis longus, ^^^ and to a small branch, 

 which sometimes originates from one of the branches to the pec- 



(1) Subclavius of Rolleston ; pectoralis secundus of authors. The nerve for this muscle 

 sometimes arises from the first nerve of the plexus directly. 



(2) Deltoideus minor of Tiedemann. 



(3) Levator humeri of Tiedemann. 



(4) Infraspinatus of Meckel, 



(5 Pectoralis minimus of Tiedemann ; subclavius of Retzius. 



