70 AIR. F. G. PARSONS ON THE 



The Nervous Ststem. 



The Brachial plexus is formed bj the 5th, 6th, 7th, and 8th 

 cervical and part of the 1st thoracic nerve, its arrangement is 

 singularly like that of Man, 



The Mnsculo-ciitaneous nerve coines from the 6th and 7th 

 cervical and supplies the biceps brachialis anticus and the skin 

 of the outer side of the forearm. 



The Median nerve rises by the usual two heads and gets its 

 fibres from the 6th, 7th, 8th cervical and 1st thoracic nerves ; it 

 passes through the supracondylar foramen with the brachial 

 artery, supplies all the muscles of the flexor surface of the fore- 

 arm except the greater part of the flexor profundus digitorum, 

 and then accDmpanies the median artery to the palm, where it 

 ends by supplying the two digits. 



The Ulnar nerve comes from the 8th cervical and 1st thoracic; 

 as the minimus digit is suppressed it ends in the flexor profundus 

 digitorum. 



The Internal cutaneous supplies the inner side of the forearm 

 with cutaneous twigs. 



The Internal anterior thoracic is, as usual in the lower 

 mammals, very large ; it supplies all the ventral part of the 

 panniculus, and apparently some at least of the dorsal part, as 

 well as a great deal of the pectoral mass. The more cephalic 

 part of this mass is supplied by the external anterior thoracic 

 from the 6th and 7th cervical. 



The Muscnlo-spiral nerve comes from all the nerves forming 

 tlie plexus except the 5th cervical. After supplying the triceps 

 and the skin of the arm, it divides at the elbow into radial and 

 posterior interosseous, the former of which supplies the dorsal 

 surfaces of the two digits, while the latter passes deep to the 

 supinator brevis and supplies the muscles on the dorsal surface 

 of the forearm, ending, as usual, on the dorsum of the carpus. 

 In the Kangaroo and Phalanger I have found that the area 

 usually supplied by the radial has a branch from the median 

 instead. Choeropus shows that this is not a constant occurrence 

 in marsupials. 



The Gircumjleoo nerve as usual supplies the deltoid, teres 

 minor, and skin over the deltoid, I failed to find any gangliform 

 enlargement on the nerve to the teres minor. 



